
CARMASponsored Seminar Series: Colloquia, Seminars and More.
Last updated Wednesday, 23 Sep, 2015

[Note: events are listed by descending date.]
 CARMA SEMINAR
 Speaker: Dr Philipp Braun, School of Electrical Engineering and Computer Science, The University of Newcastle
 Title: Obstacle avoidance controller design
 Location: Room V205, Mathematics Building (Callaghan Campus) The University of Newcastle
 Time and Date: 4:00 pm, Thu, 22^{nd} Mar 2018
 Abstract:
Constructive methods for the controller design for dynamical systems subject to bounded state constraints have only been investigated by a limited number of researchers. The construction of robust control laws is significantly more difficult compared to unconstrained problems due to the necessity of discontinuous feedback laws. A rigorous understanding of the problem is however important in obstacle or collision avoidance for mobile robots, for example. In this talk we present preliminary results on the controller design for obstacle avoidance of linear systems based on the notation of hybrid systems. In particular, we derive a discontinuous feedback law, globally stabilizing the origin while avoiding a neighborhood around an obstacle. In this context, additionally an explicit bound on the maximal size of the obstacle is provided.
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 CARMA SEMINAR
 Speaker: Prof Richard Brent, CARMA, The University of Newcastle
 Title: Jonathan Borwein and Pi
 Location: Room V205, Mathematics Building (Callaghan Campus) The University of Newcastle
 Time and Date: 1:59 pm, Wed, 14^{th} Mar 2018
 Abstract:
The late Professor Jonathan Borwein was fascinated by the constant
$\pi$. Some of his talks on this topic can be found on the CARMA website.
This homage to Jon is based on my talk at the Jonathan Borwein Commemorative
Conference. I will describe some algorithms for the highprecision
computation of $\pi$ and the elementary functions, with particular reference
to the book Pi and the AGM by Jon and his brother Peter Borwein.
Here "AGM" is the arithmeticgeometric mean
of Gauss and Legendre. Because the AGM has secondorder convergence, it
can be combined with FFTbased fast multiplication algorithms to give fast
algorithms for the \hbox{$n$bit} computation of $\pi$.
I will survey a few of the results and algorithms that were of interest to
Jon. In several cases they were either discovered or improved by him. If
time permits, I will also mention some new results that would have been of
interest to Jon.
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 CARMA SEMINAR
 CARMA Special Semester on Computation and Visualisation
 Speaker: Dr Bishnu Lamichhane, CARMA, The University of Newcastle
 Title: Computing and visualising the solutions of partial differential equations
 Location: Room V206, Mathematics Building (Callaghan Campus) The University of Newcastle
 Time and Date: 3:00 pm, Tue, 13^{th} Mar 2018
 Abstract:
The finite element method has become the most powerful approach in solving partial differential equations arising in modern engineering and physical applications. We present computation and visualisation of the solutions of some applied partial differential equations using the finite element method for most of our examples. Our examples come from solid and fluid mechanics, image processing and heat conduction in sliding meshes.
About the speaker: Dr Lamichhane was awarded the MSc in Industrial Mathematics from the University of Kaiserslautern in 2001, and the PhD in Mathematics from the University of Stuttgart in 2006. He took a postdoctoral fellow at the Australian National University in 2008 and is now a senior lecturer at the University of Newcastle. Dr Lamichhane’s main interests are numeral analysis, differential equations and applied mathematics and his recent research focus is on the approximation of solutions of partial differential equations using the finite element method.
 To participate remotely, connect to the ViewMe meeting called "carmaspecial" (you can enter that name, or the meeting number 8882491714). This will be persistant for future talks in this series. The ViewMe client is free and you do not need an account. You can install ViewMe on a computer or phone to take part, or use the web interface (Firefox or Chrome) at https://viewme.ezuce.com/webrtc/?meetingID=8882491714. It's quite easy to use, but for assistance please contact Andrew.Danson@newcastle.edu.au. Some guides are available at https://viewme.ezuce.com/support/guidestutorials/.
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 CARMA SEMINAR
 Speaker: Dr Hadi Charkhgard, University of South Florida
 Title: Recent Algorithmic Advances on MultiObjective Integer Programming
 Location: Room V205, Mathematics Building (Callaghan Campus) The University of Newcastle
 Time and Date: 4:00 pm, Thu, 8^{th} Mar 2018
 Abstract:
Multiobjective optimization provides decisionmakers with a complete view of the tradeoffs between their objective functions that are attainable by feasible solutions. Since many problems can be formulated as integer programs, the development of efficient and reliable multiobjective integer programming solvers may have significant benefits for problem solving in industry and government. However, the conjunction of multiple objectives and integrality yields problems that can be challenging to solve. So, this talk provides an overview of a few new exact as well as heuristic algorithms for this class of optimization problems. In particular, the talk focuses on computing the nondominated frontier and also the problem of optimization over the frontier. It is worth mentioning that all of the algorithms and their corresponding opensource software packages are developed in MultiObjective Optimization Laboratory at the University of South Florida.
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 CARMA SEMINAR
 CARMA Special Semester on Computation and Visualisation
 Speaker: Dr Keith Nesbitt, The University of Newcastle
 Title: Designing Multisensory Displays of Abstract Data
 Location: Room V206, Mathematics Building (Callaghan Campus) The University of Newcastle
 Time and Date: 3:00 pm, Tue, 6^{th} Mar 2018
 Abstract:
The rapid increase in available information has led to many attempts to automatically locate patterns in large, abstract, multiattributed information spaces. These techniques are often called data mining and have met with varying degrees of success. An alternative approach to automatic pattern detection is to keep the user in the exploration loop by developing displays that enhance their natural sensory abilities to detect patterns. This approach, whether visual, auditory, or touch based, can assist a domain expert to search their data for useful relationships. However, designing models of the abstract data and defining appropriate sensory mappings are critical tasks in building such a system. Intuitive multisensory displays (visual, auditory, touch) of abstract data are difficult to design and the process needs to carefully consider human perceptual and cognitive abilities. This talk will introduce a taxonomy that helps designers consider the range of sensory mappings, along with appropriate guidelines, when building such multisensory displays. To illustrate this process a case study in the domain of stock market data is also presented.
About the speaker: Keith completed his Bachelor's degree in Mathematics at Newcastle University in 1988 and his Masters in Computing in 1993. Between 19891999, Keith worked on applied computer research for BHP Research. His PhD examined the design of multisensory displays for stock market data and was completed at Sydney University in 2003. His work has received international recognition, being selected among the best visualisations and consequently exhibited at a number of international locations and reviewed in the prestigious journal Science. In 2007 he completed a postdoctoral year in Boston working at the New England Complex Systems Institute visualising health related data. He has expertise in the fields of Human Interface Design, Computer Games, Virtual Reality, Immersive Analytics, and the theory of Perception and Cognition related to the design of multisensory user interfaces. Keith currently works in the school of School of Electrical Engineering and Computing at the University of Newcastle, Australia where he teaches Computer Games and Programming. While his background is in Computer Science, he has also exhibited his paintings in 11 exhibits and provided lyrics for 5 CDS and a musical. You can find more about his art and science at www.knesbitt.com.
 To participate remotely, connect to the ViewMe meeting called "carmaspecial" (you can enter that name, or the meeting number 8882491714). This will be persistant for future talks in this series.
The ViewMe client is free and you do not need an account. You can install ViewMe on a computer or phone to take part, or use the web interface (Firefox or Chrome) at https://viewme.ezuce.com/webrtc/?meetingID=8882491714.
It's quite easy to use, but for assistance please contact Andrew.Danson@newcastle.edu.au. Some guides are available at https://viewme.ezuce.com/support/guidestutorials/.
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 CARMA SEMINAR
 CARMA Special Semester on Computation and Visualisation
 Speaker: Associate Professor Stephan Chalup , The University of Newcastle
 Title: Artificial Neural Networks  Old and New
 Location: Room V205, Mathematics Building (Callaghan Campus) The University of Newcastle
 Time and Date: 3:00 pm, Tue, 27^{th} Feb 2018
 Abstract:
The human brain is still one of the most powerful and at the same time most energy efficient computers. Artificial neural networks (ANN) are inspired by their biological counterparts and the workings of biological nervous systems. ANNs were among the most popular machine learning algorithms in the 198090s. However, after 2000 other algorithms came to be regarded as more accurate and practical. In 2012 ANNs came back with a big bang: a new form of biologicallyinspired ANNs, deep convolutional neural networks, showed surprisingly good performances on image classification and object detection tasks, far superior to all other methods available. Since then deep networks have breaken records in many application domains, from object detection for autonomous vehicles to playing the game of Go and skin health diagnostics. Deep networks are currently revolutionising machine learning in academia and industry. They can be regarded as the most disruptive technology in any industry that involves machine learning, artificial intelligence, pattern recognition, data mining or control. This seminar aims at providing an overview of ANNs  old and new  with a special view towards how visualisations could help to explain how they work.
About the speaker: Stephan Chalup (Ph.D., Dipl.Math.) is an associate professor at the University of Newcastle in Australia, where he is leading the Interdisciplinary Machine Learning Research Group and the Newcastle Robotics Lab. He studied mathematics with neuroscience at the University of Heidelberg and completed his Ph.D. in Computing Science at the Machine Learning Research Centre at Queensland University of Technology (QUT) in 2002. Stephan has published 100 research articles and is on the editorial boards of several journals. He is member of the University of Newcastle's Priority Research Centre CARMA.
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 CARMA SEMINAR
 Speaker: Alejandra Garrido, Heinrich Heine University Düsseldorf
 Title: Profinite completions of groups acting on rooted trees
 Location: Room V205, Mathematics Building (Callaghan Campus) The University of Newcastle
 Time and Date: 4:00 pm, Thu, 22^{nd} Feb 2018
 Abstract:
Groups of rooted tree automorphisms, and (weakly) branch groups in particular, have received considerable attention in the last few decades, due to the examples with unexpected properties that they provide, and their connections to dynamics and automata theory. These groups also showcase interesting phenomena in profinite group theory. I will discuss some of these and other profinite completions that one can use to study these groups, and how to find them. All these concepts will be defined in the talk.
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 CARMA SEMINAR
 Speaker: Ernst Stephan, Institute for Applied Mathematics, Leibniz University Hannover
 Title: Adaptive and higherorder time domain boundary elements for the wave equation
 Location: Room V205, Mathematics Building (Callaghan Campus) The University of Newcastle
 Time and Date: 4:00 pm, Tue, 21^{st} Nov 2017
 Abstract:
We present $h$ and $p$versions of the time domain boundary element method for boundary and screen problems for the wave equation in $\mathbb{R}^3$. First, graded meshes are shown to recover optimal approximation rates for solution in the presence of edge and corner singularities on screens. Then an a posteriori error estimate is presented for general discretizations, and it gives rise to adaptive mesh refinement procedures. We also discuss preliminary results for $p$ and $hp$versions of the time domain boundary element method. Numerical experiments illustrate the theory. Joint with H. Gimperlein and D. Stark, HeriotWatt University, Edinburgh.
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 CARMA SEMINAR
 Speaker: Dr Davor Dragicevic, University of NSW
 Title: Lyapunov functions for hyperbolic behaviour
 Location: Room V205, Mathematics Building (Callaghan Campus) The University of Newcastle
 Time and Date: 4:00 pm, Tue, 19^{th} Sep 2017
 Abstract:
I will present a brief survey of some recent results that deal with the characterization of hyperbolic dynamics in terms of the existence of appropriate Lyapunov functions.
The main novelty of these results lies in the fact that they consider noninvertible and infinitedimensional dynamics. This is a joint work with L. Barreira, C. Preda and C. Valls.
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 CARMA SEMINAR
 Speaker: Dr Bishnu Lamichhane, CARMA, The University of Newcastle
 Title: My recent journey into mixed finite element methods
 Location: Room V205, Mathematics Building (Callaghan Campus) The University of Newcastle
 Time and Date: 4:00 pm, Tue, 8^{th} Aug 2017
 Abstract:
In this talk I will briefly introduce the mixed finite element method and show their applications. I consider Poisson, elasticity, Stokes and biharmonic equations for the applications of the mixed finite element method. The mixed finite element method also arises naturally in Stokes flow, multiphysics problems as well as when we consider nonconforming discretisation techniques. I will also present my recent works on the mixed finite element method for biharmonic and ReissnerMindlin plate equations.
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 CARMA SEMINAR
 Speaker: A/Prof Chris Kellett, School of Electrical Engineering and Computer Science, The University of Newcastle
 Title: Back and Forth in Lyapunov's Second Method  Nonuniform Subtleties
 Location: Room V205, Mathematics Building (Callaghan Campus) The University of Newcastle
 Time and Date: 4:00 pm, Tue, 13^{th} Jun 2017
 Abstract:
Lyapunov's second or direct method provides an easytocheck sufficient condition for stability properties of equilibria. The converse question  given a stability property, does there exist an appropriate Lyapunov function?  has been fundamental in differentiating and classifying different stability properties, particularly with regards to "uniform" stability.
In this talk, I will review the usual textbook definitions for Lyapunov functions for timevarying systems and describe where they are deficient. Some interesting new sufficient (and probably necessary) conditions pop up along the way.
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 CARMA SEMINAR
 Speaker: Prof. André Nies, Department of Computer Science, The University of Auckland
 Title: The complexity of the isomorphism problem for t.d.l.c. and other types of groups
 Location: Room V205, Mathematics Building (Callaghan Campus) The University of Newcastle
 Time and Date: 4:00 pm, Thu, 1^{st} Jun 2017
 Abstract:
We determine the Borel complexity of the topological isomorphism problem for profinite, t.d.l.c., and Roelcke precompact nonArchimedean groups, by showing it is equivalent to graph isomorphism.
For oligomorphic groups we merely establish this as an upper bound.
Joint work with Kechris and Tent.
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 CARMA SEMINAR
 Speaker: Dr Philipp Braun, School of Electrical Engineering and Computer Science, The University of Newcastle
 Title: (Nonsmooth) Control Lyapunov Functions: Stabilization and Destabilization of Nonlinear Systems
 Location: Room V205, Mathematics Building (Callaghan Campus) The University of Newcastle
 Time and Date: 4:00 pm, Tue, 23^{rd} May 2017
 Abstract:
Control Lyapunov functions (CLFs) for the control of dynamical systems have faded from the spotlight over the last years even though their full potential has not been explored yet. To reactivate research on CLFs we review existing results on Lyapunov functions and (nonsmooth) CLFs in the context of stability and stabilization of nonlinear dynamical systems. Moreover, we highlight open problems and results on CLFs for destabilization. The talk concludes with ideas on Complete CLFs, which combine the concepts of stability and instability. The results presented in the talk are illustrated and motivated on the examples of a nonholonomic integrator and Artstein's circles.
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 CARMA SEMINAR
 Speaker: Prof Wadim Zudilin, CARMA, The University of Newcastle
 Title: Hypergeometric heritage of W.N. Bailey
 Location: Room V205, Mathematics Building (Callaghan Campus) The University of Newcastle
 Time and Date: 4:00 pm, Tue, 16^{th} May 2017
 Abstract:
Part of my 2016 SSP included completion of a semihistorical review on the mathematics of W.N. Bailey, a familiar name in some combinatorics circles in relation with the "Bailey lemma" and "Bailey pairs." My personal encounters with the mathematician from the first half of the 20th century were somewhat different and more related to applications of special functions to number theory—the subject Bailey had never dealt with himself. One motivation for my writing was the place where I spent my SSP—details to be revealed in the talk. There will be some formulas displayed, sometimes scary, but they will serve as a background to historical achievements. Broad audience is welcome.
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 CARMA SEMINAR
 Speaker: Dr Matt Tam, Institute for Numerical and Applied Mathematics, University of Goettingen
 Title: Symbolic convex analysis
 Location: Room V205, Mathematics Building (Callaghan Campus) The University of Newcastle
 Time and Date: 4:00 pm, Thu, 11^{th} May 2017
 Abstract:
In this talk we consider a class of monotone operators which are appropriate for symbolic representation and manipulation within a computer algebra system. Various structural properties of the class (e.g., closure under taking inverses, resolvents) are investigated as well as the role played by maximal monotonicity within the class. In particular, we show that there is a natural correspondence between our class of monotone operators and the subdifferentials of convex functions belonging to a class of convex functions deemed suitable for symbolic computation of Fenchel conjugates which were previously studied by Bauschke & von Mohrenschildt and by Borwein & Hamilton. A number of illustrative computational examples utilising the introduced class of operators will be provided including computation of proximity operators, recovery of a convex penalty function associated with the hard thresholding operator, and computation of superexpectations, superdistributions and superquantiles with specialization to risk measures.
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 CARMA SEMINAR
 Speaker: Nicolai Stammeier, The University of Oslo
 Title: The internal structure of ZappaSzép products of right LCM semigroups
 Location: Room V205, Mathematics Building (Callaghan Campus) The University of Newcastle
 Time and Date: 4:00 pm, Thu, 23^{rd} Mar 2017
 Abstract:
In recent joint work on equilibrium states on semigroup C*algebras with Afsar, Brownlowe, and Larsen, we discovered that the structure of equilibrium states admits an elegant description in terms of substructures of the original semigroup. More precisely, we consider two almost contrary subsemigroups and related features to obtain a unifying picture for a number of predating case studies. Somewhat surprisingly, all the examples from the case studies satisfy a list of four abstract properties (and are then called admissible). The nature and presence of these properties is yet to be fully understood. In this talk, I will focus on a class of examples arising as ZappaSzép products of right LCM semigroups which showcases some interesting features. No prerequisites in operator algebras are required to follow this talk.
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 CARMA SEMINAR
 Speaker: Dr Jeff Hogan, CARMA, The University of Newcastle
 Title: A Guided Tour of Harmonic Analysis
 Location: Room V205, Mathematics Building (Callaghan Campus) The University of Newcastle
 Time and Date: 4:00 pm, Tue, 14^{th} Mar 2017
 Abstract:
This talk gives an outline of (mostly unfinished) work done collaboratively while on sabbatical in semester 2 last year. Join me as we travel through the USA, Germany, Belgium and Austria. Your guide will share offthebeatentrack highlights such as quaternionic splines, prolate shift systems, higherdimensional Hardy, PaleyWiener and Bernstein spaces, the Clifford Fourier transform, multidimensional prolates, and a Jon Borweininspired optimizationbased approach to the construction of multidimensional wavelets. Breakfast not included.
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 CARMA SEMINAR
 Speaker: Duc Tran, The University of Newcastle
 Title: Incremental Stability Properties for DiscreteTime Systems
 Location: Room V205, Mathematics Building (Callaghan Campus) The University of Newcastle
 Dates: Wed, 30^{th} Nov 2016  Wed, 30^{th} Nov 2016
 Abstract:
Incremental stability describes the asymptotic behavior
between any two trajectories of dynamical systems. Such
properties are of interest, for example, in the study of
observers or synchronization of chaos. In this paper, we
develop the notions of incremental stability and
incremental inputtostate stability (ISS) for
discretetime systems. We derive Lyapunov function
characterizations for these properties as well as a useful
summationtosummation formulation of the incremental
stability property.
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 CARMA SEMINAR
 Speaker: Andrew Goh, The University of Newcastle
 Title: Solving free group equations on a computer
 Location: Room V205, Mathematics Building (Callaghan Campus) The University of Newcastle
 Dates: Wed, 30^{th} Nov 2016  Wed, 30^{th} Nov 2016
 Abstract:
I will discuss how to solve free group equations using a practical computer program. Ciobanu, Diekert and Elder recently gave a theoretical algorithm which runs in nondeterministic space $n\log n$, but implementing their method as an actual computer program presents many challenges, which I will describe.
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 CARMA SEMINAR
 Speaker: George Havas, The University of Queensland
 Title: Commutator identities as products of powers
 Location: Room V205, Mathematics Building (Callaghan Campus) The University of Newcastle
 Time and Date: 11:00 am, Mon, 28^{th} Nov 2016
 Abstract:
Some Engel words and also commutators of commutators can be expressed as products of powers. I discuss recent work of Colin Ramsay in this area, using PEACE (Proof Extraction After Coset Enumeration), and in particular provide expressions for commutators of commutators as short products of cubes.
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 CARMA SEMINAR
 Speaker: Dr David Simmons, University of York
 Title: Unconventional height functions in Diophantine approximation
 Location: Room V108, Mathematics Building (Callaghan Campus) The University of Newcastle
 Time and Date: 4:00 pm, Thu, 28^{th} Jul 2016
 Abstract:
The standard height function $H(\mathbf p/q) = q$ of simultaneous approximation can be calculated by taking the LCM (least common multiple) of the denominators of the coordinates of the rational points: $H(p_1/q_1,\ldots,p_d/q_d) = \mathrm{lcm}(q_1,\ldots,q_m)$. If the LCM operator is replaced by another operator such as the maximum, minimum, or product, then a different height function and thus a different theory of simultaneous approximation will result. In this talk I will discuss some basic results regarding approximation by these nonstandard height functions, as well as mentioning their connection with intrinsic approximation on Segre manifolds using standard height functions. This work is joint with Lior Fishman.
Dr Simmons is a visitor of Dr Mumtaz Hussain.
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 CARMA SEMINAR
 Speaker: Dr Faustin Adiceam, University of York
 Title: On the minimum of a positive definite quadratic form over nonzero lattice points. Theory and applications.
 Location: Room V108, Mathematics Building (Callaghan Campus) The University of Newcastle
 Time and Date: 3:00 pm, Thu, 28^{th} Jul 2016
 Abstract:
Let $\Sigma_d^{++}(\R)$ be the set of positive definite matrices with determinant 1 in dimension $d\ge 2$. Identifying two $SL_d(\Z)$congruent elements in $\Sigma_d^{++}(\R)$ gives rise to the space of reduced quadratic forms of determinant one, which in turn can be identified with the locally symmetric space $X_d:=SL_d(\Z)\backslash SL_d(\R)\slash SO_d(\R)$. Equip the latter space with its natural probability measure coming from the Haar measure on $SL_d(\R)$. In 1998, Kleinbock and Margulis established very sharp estimates for the probability that an element of $X_d$ takes a value less than a given real number $\delta>0$ over the nonzero lattice points $\Z^d\backslash\{ \bm{0} \}$.
This talk will be concerned with extensions of such estimates to a large class of probability measures arising either from the spectral or the Cholesky decomposition of an element of $\Sigma_d^{++}(\R)$. The sharpness of the bounds thus obtained are also established for a subclass of these measures.
This theory has been developed with a view towards application to Information Theory. Time permitting, we will briefly introduce this topic and show how the estimates previously obtained play a crucial role in the analysis of the perfomance of communication networks.
This is work joint with Evgeniy Zorin (University of York). Dr Adiceam is a visitor of Dr Mumtaz Hussain.
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 CARMA SEMINAR
 Speaker: Milutin Brankovic, unknown or leave blank,
 Title: Lehmer's Question and the Newton Polytope
 Location: Room V205, Mathematics Building (Callaghan Campus) The University of Newcastle
 Time and Date: 4:00 pm, Thu, 28^{th} Apr 2016
 Abstract:
Lehmer's famous question concerns the existence of monic integer coefficient polynomials with Mahler measure smaller than a certain constant. Despite significant partial progress, the problem has not been fully resolved since its formulation in 1933. A powerful result independently proven by Lawton and Boyd in the 1980s establishes a connection between the classical Mahler measure of single variable polynomials and the generalized Mahler measure of multivariate polynomials. This led to speculation that it may be possible to answer Lehmer's question in the affirmative with a multivariate polynomial although the general consensus among researchers today is that no such polynomial exists. We show that each possible candidate among two variable polynomials corresponding to curves of genus 1 can be birationally mapped onto a polynomial with Mahler measure greater than Lehmer's constant. Such birational maps are expected to preserve the Mahler measure for large values of a certain parameter.
Milutin is a completing Honours Student of Wadim Zudilin.
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 CARMA SEMINAR
 Speaker: Mark Kayll, University of Montana
 Title: Adventures with Burnoff Chipfiring Games
 Location: Room V129, Mathematics Building (Callaghan Campus) The University of Newcastle
 Time and Date: 4:00 pm, Thu, 7^{th} Apr 2016
 Abstract:
Start by placing piles of indistinguishable chips on the vertices of a graph. A
vertex can fire if it's supercritical; i.e., if its chip count exceeds its valency.
When this happens, it sends one chip to each neighbour and annihilates one
chip. Initialize a game by firing all possible vertices until no supercriticals
remain. Then drop chips onebyone on randomly selected vertices, at each
step firing any supercritical ones. Perhaps surprisingly, this seemingly haphazard
process admits analysis. And besides having diverse applications (e.g., in
modelling avalanches, earthquakes, traffic jams, and brain activity), chipfiring
reaches into numerous mathematical crevices. The latter include, alphabetically,
algebraic combinatorics, discrepancy theory, enumeration, graph theory,
stochastic processes, and the list could go on (to zonotopes). I'll share some
joint work—with Dave Perkins—that touches on a few items from this list.
The talk'll be accessible to nonspecialists. Promise!
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 CARMA SEMINAR
 Speaker: Jim Cooper, President & CEO, Maplesoft
 Title: The Future of Education
 Location: Room V206, Mathematics Building (Callaghan Campus) The University of Newcastle
 Time and Date: 2:30 pm, Wed, 10^{th} Feb 2016
 Abstract:
In this presentation we address the issues and challenges for Future of Education and how Maplesoft is committed to offers Tools such as Möbius™ to handle these challenges. Möbius is a comprehensive online courseware environment that focuses on science, technology, engineering, and mathematics (STEM). It is built on the notion that people learn by doing. With Möbius, your students can explore important concepts using engaging, interactive applications, visualize problems and solutions, and test their understanding by answering questions that are graded instantly. Throughout the entire lesson, students remain actively engaged with the material and receive constant feedback that solidifies their understanding.
When you use Möbiusto develop and deliver your online offerings, you remain in full control of your content and the learning experience.
 Bring your online vision to life, including online courses, openaccess courses, formative testing, placement and remediation programs, independent learning, outreach programs, and flipped or blended classrooms.
 Provide exactly the content you want, from individual lessons and textbook supplements, to full courses, remedial materials, enrichment content, and more.
 Choose the learning experience by allowing students open access to your course material or guiding them along a specific learning path.
 Stay in control of your content, creating and customizing materials as you wish to suit your needs.
 Save your students money by dropping a traditional textbook, while simultaneously improving the learning experience.
For more information on Möbiusplease visit http://maplesoft.com/products/Mobius/.
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 CARMA SEMINAR
 Speaker: Ernst Stephan, Insitut fur Angewandte Mathematik (IfAM), Leibniz Universitat Hannover
 Title: hpadaptive Interior Penalty FEM for Elliptic Obstacle Problems DG for Laplace, $C^0$ for biLaplace
 Location: Room V205, Mathematics Building (Callaghan Campus) The University of Newcastle
 Time and Date: 4:00 pm, Tue, 24^{th} Nov 2015
 Abstract:
Firstly, from [1] we consider a mixed formulation for an elliptic obstacle problem for
a 2nd order operator and present an hpFE interior penalty discontinous Galerkin
(IPDG) method. The primal variable is approximated by a linear combination of
GaussLobattoLagrange(GLL)basis functions, whereas the discrete Lagrangian
multiplier is a linear combination of biorthogonal basis functions. A residual based
a posteriori error estimate is derived. For its construction the approximation error
is split into a discretization error of a linear variational equality problem and
additional consistency and obstacle condition terms.
Secondly, an hpadaptive $C^0$interior penalty method for the biLaplace obstacle
problem is presented from [2]. Again we take a mixed formulation using GLLbasis functions for the primal variable and biorthogonal basis functions for the
Lagrangian multiplier and present also a residual a posteriori error estimate. For
both cases (2nd and 4th order obstacle problems) our numerical experiments clearly
demonstrate the superior convergence of the hpadaptive schemes compared with
uniform and hadaptive schemes.
References
[1] L.Banz, E.P.Stephan, A posteriori error estimates of hpadaptive IPDGFEM for elliptic
obstacle problems, Applied Numerical Mathematics 76,(2014) 7692
[2] L.Banz, B.P.Lamichhane, E.P.Stephan, An hpadaptive $C^0$interior penalty method for the
obstacle problem of clamped Kirchhoff plates, preprint (2015)
(Joint work with Lothar Banz, University Salzburg, Austria)
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 CARMA SEMINAR
 Speaker: Vladimir Peller, Michigan State University
 Title: Functions of noncommuting selfadjoint operators under perturbation
 Location: Room V205, Mathematics Building (Callaghan Campus) The University of Newcastle
 Time and Date: 4:00 pm, Thu, 5^{th} Nov 2015
 Abstract:
I am going to discuss a construction of functional calculus $$f\mapsto f(A,B),$$ where $A$ and $B$ are noncommuting selfadjoint operators. I am going to discuss the problem of estimating the norms $\f(A_1,B_1)f(A_2,B_2)\$, where the pair $(A_2,B_2)$ is a perturbation of the pair $(A_1,B_1)$.
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 CARMA SEMINAR
 Speaker: Prof Richard Brent, CARMA, The University of Newcastle
 Title: Some Identities involving Products of Gamma Functions: a Case Study in Experimental Mathematics
 Location: Room V205, Mathematics Building (Callaghan Campus) The University of Newcastle
 Time and Date: 2:00 pm, Tue, 27^{th} Oct 2015
 Abstract:
We consider identities satisfied by discrete analogues of Mehtalike integrals.
The integrals are related to Selberg’s integral and the Macdonald conjectures.
Our discrete analogues have the form
$$S_{\alpha,\beta,\delta} (r,n) :=
\sum_{k_1,...,k_r\in\mathbb{Z}}
\prod_{1\leq i < j\leq r}
k_i^\alpha  k_j^\alpha^\beta
\prod_{j=1}^r k_j^\delta
\binom{2n}{n+k_j},$$
where $\alpha,\beta,\delta,r,n$ are nonnegative integers subject to certain restrictions.
In the cases that we consider, it is possible to express $S_{\alpha,\beta,\delta} (r,n)$ as a
product of Gamma functions and simple functions such as powers of two.
For example, if $1 \leq r \leq n$, then
$$S_{2,2,3} (r,n) =
\prod_{j=1}^r
\frac{(2n)!j!^2}{(nj)!^2}.$$
The emphasis of the talk will be on how such identities can be obtained,
with a high degree of certainty, using numerical computation. In other cases
the existence of such identities can be ruled out, again with a high degree of
certainty. We shall not give any proofs in detail, but will outline the ideas
behind some of our proofs. These involve $q$series identities and arguments
based on nonintersecting lattice paths.
This is joint work with Christian Krattenthaler and Ole Warnaar.
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 CARMA SEMINAR
 Speaker: Michael Schönlein, Universität Würzburg
 Title: Asymptotic stability and Lyapunov functions for a class of abstract positive systems
 Location: Room V205, Mathematics Building (Callaghan Campus) The University of Newcastle
 Time and Date: 4:00 pm, Fri, 23^{rd} Oct 2015
 Abstract:
We consider the stability of a class of abstract positive systems originating from the recurrence analysis of stochastic systems, such as multiclass queueing networks and semimartingale reflected Brownian motions. We outline that this class of systems can also be described by differential inclusions in a natural way. We will point out that because of the positivity of the systems the setvalued map defining the differential inclusion is not upper semicontinuous in general and, thus, wellknown characterizations of asymptotic stability in terms of the existence of a (smooth) Lyapunov function cannot be applied to this class of positive systems. Following an abstract approach, based on common properties of the positive systems under consideration, we show that asymptotic stability is equivalent to the existence of a Lyapunov function. Moreover, we examine the existence of smooth Lyapunov functions. Putting an assumption on the trajectories of the positive systems which demands for any trajectory the existence of a neighboring trajectory such that their difference grows linearly in time and distance of the starting points, we prove the existence of a $C^\infty$smooth Lyapunov function. Looking at this hypothesis from the differential inclusions perspective it turns out that differential inclusions defined by Lipschitz continuous setvalued maps taking nonempty, compact and convex values have this property.
 [Permanent event link]
 CARMA SEMINAR
 Speaker: Dr Björn Rüffer, CARMA, The University of Newcastle
 Title: Separable Lyapunov functions for monotone systems
 Location: Room V205, Mathematics Building (Callaghan Campus) The University of Newcastle
 Time and Date: 4:00 pm, Thu, 24^{th} Sep 2015
 Abstract:
We consider monotone systems defined by ODEs on the positive orthant
in $\mathbb{R}^n$. These systems appear in various areas of
application, and we will discuss in some level of detail one of these
applications related to largescale systems stability analysis.
Lyapunov functions are frequently used in stability analysis of
dynamical systems. For monotone systems so called sum and
maxseparable Lyapunov functions have proven very successful. One can
be written as a sum, the other as a maximum of functions of scalar
arguments.
We will discuss several constructive existence results for both
types of Lyapunov function. To some degree, these functions can be
associated with left and right eigenvectors of an appropriate
mapping. However, and perhaps surprisingly, examples will demonstrate
that stable systems may admit only one or even neither type of
separable Lyapunov function.
 [Permanent event link]
 CARMA SEMINAR
 Location: Room V205, Mathematics Building (Callaghan Campus) The University of Newcastle
 Time and Date: 1:00 pm, Thu, 24^{th} Sep 2015
 Practice talks for the 2015 AustMS Meeting.
 Speaker: Mr Matthew Tam, School of Mathematical and Physical Sciences, The University of Newcastle
 Title: Reconstruction Algorithms for Blind Ptychographic Imaging
 Abstract for Reconstruction Algorithms for Blind Ptychographic Imaging:
In scanning ptychography, an unknown specimen is illuminated by a localised
illumination function resulting in an exitwave whose intensity is observed in
the farfield. A ptychography dataset is a series of these observations, each of
which is obtained by shifting the illumination function to a different position
relative to the specimen with neighbouring illumination regions overlapping.
Given a ptychographic data set, the blind ptychography problem is to
simultaneously reconstruct the specimen, illumination function, and relative
phase of the exitwave. In this talk I will discuss an optimisation framework
which reveals current stateoftheart reconstruction methods in ptychography
as (nonconvex) alternating minimizationtype algorithms. Within this framework,
we provide a proof of global convergence to critical points using the
KurdykaŁojasiewicz property.
 Speaker: Assoc Prof Murray Elder, CARMA, The University of Newcastle
 Title: Using random walks to detect amenability in finitely generated groups
 Abstract for Using random walks to detect amenability in finitely generated groups:
We use random walks to experimentally compute the first few terms of the
cogrowth series for a finitely presented group. We propose candidates for the amenable radical of any nonamenable group, and a
Følner sequence for any amenable group, based on convergence properties of
random walks.
 Speaker: David Franklin, School of Mathematical and Physical Sciences, The University of Newcastle
 Title: Hardy Spaces and PaleyWiener Spaces for Cliffordvalued functions
 Abstract for Hardy Spaces and PaleyWiener Spaces for Cliffordvalued functions:
The Hardy and PaleyWiener Spaces are defined due to important structural
theorems relating the support of a function's Fourier transform to the growth
rate of the analytic extension of a function. In this talk we show that
analogues of these spaces exist for Cliffordvalued functions in n dimensions,
using the CliffordFourier Transform of Brackx et al and the monogenic ($n+1$
dimensional) extension of these functions.
 [Permanent event link]
 CARMA SEMINAR
 Speaker: George Havas, The University of Queensland
 Title: Group theoretic proofs by coset enumeration
 Location: Room V205, Mathematics Building (Callaghan Campus) The University of Newcastle
 Time and Date: 3:00 pm, Wed, 23^{rd} Sep 2015
 Abstract:
Given a finite presentation of a group, proving properties of the group
can be difficult. Indeed, many questions about finitely presented groups
are unsolvable in general. Algorithms exist for answering some questions
while for other questions algorithms exist for verifying the truth of
positive answers. An important tool in this regard is the ToddCoxeter
coset enumeration procedure. It is possible to extract formal proofs
from the internal working of coset enumerations. We give examples of how
this works, and show how the proofs produced can be mechanically verified
and how they can be converted to alternative forms. We discuss these
automatically produced proofs in terms of their size and the insights
they offer. We compare them to hand proofs and to the simplest possible
proofs. We point out that this technique has been used to help solve
a longstanding conjecture about an infinite class of finitely presented
groups.
 [Permanent event link]
 CARMA SEMINAR
 Speaker: Prof Levent Tunçel, University of Waterloo
 Title: Superlinear Convergence of polynomialtime interiorpoint methods for convex optimization
 Location: Room V205, Mathematics Building (Callaghan Campus) The University of Newcastle
 Time and Date: 4:00 pm, Thu, 17^{th} Sep 2015
 Abstract:
We propose new pathfollowing predictorcorrector algorithms for
solving convex optimization problems in conic form.
The main structural properties used in our design and analysis
of the algorithms hinge on some key properties of a special class of
very smooth, strictly convex barrier functions.
Even though our analysis has primal and dual components, our algorithms
work with the dual iterates only, in the dual space.
Our algorithms converge globally at the same worstcase rate as the current
best polynomialtime interiorpoint methods. In addition, our algorithm
have the local superlinear convergence property under some mild assumptions.
The algorithms are based on an easily computable gradient proximity measure,
which ensures an automatic transformation of the global linear rate of
convergence to the locally superlinear one under some mild assumptions.
Our stepsize procedure for the predictor step is related to the maximum
step size (the one that takes us to the boundary).
This talk is based on joint work with Yu. Nesterov.
 [Permanent event link]
 CARMA AND AMSI LECTURE SERIES
 Speaker: Prof Michael Shelley, New York University
 Title: Boundary integral methods for flows interacting with moving and flexible structures
 Location: Room V129, Mathematics Building (Callaghan Campus) The University of Newcastle
 Time and Date: 2:00 pm, Wed, 12^{th} Aug 2015
 Abstract:
In either the inviscid limit of the Euler equations, or the viscously dominated limit of the Stokes equations, the determination of fluid flows can be reduced to solving singular integral equations on immersed structures and bounding surfaces. Further dimensional reduction is achieved using asymptotics when these structures are sheets or slender fibers. These reductions in dimension, and the convolutional secondkind structure of the integral equations, allows for very efficient and accurate simulations of complex fluidstructure interaction problems using solvers based on the Fast Multipole or related methods. These representations also give a natural setting for developing implicit timestepping methods for the stiff dynamics of elastic structures moving in fluids. I'll discuss these integral formulations, their numerical treatment, and application to simulating structures moving in highspeed flows (flapping flags and flyers), and for resolving the complex interactions of many, possibly flexible, bodies moving in microscopic biological flows.
 [Permanent event link]
 CARMA SEMINAR
 Speaker: Hendrik de Bie, Ghent University
 Title: A powerful new technique for the CliffordFourier transform
 Location: Room V205, Mathematics Building (Callaghan Campus) The University of Newcastle
 Time and Date: 4:00 pm, Thu, 23^{rd} Jul 2015
 Abstract:
In recent years, there has been quite a bit of interest in
generalized Fourier transforms in Clifford analysis and in particular
for the socalled CliffordFourier transform.
In the first part of the talk I will provide some motivation for the
study of this transform. In the second part we will develop a new
technique to find a closed formula for its integral kernel, based on the
familiar Laplace transform. As a bonus, this yields a compact and
elegant formula for the generating function of all even dimensional kernels.
 [Permanent event link]
 CARMA AND AMSI LECTURE SERIES
 Mathematical Logic and Philosophy
 Location: Room V206, Mathematics Building (Callaghan Campus) The University of Newcastle
 Time and Date: 3:00 pm, Fri, 22^{nd} May 2015
 Download: Lecture Tour Flyer (424 KB)
 Four lectures by Professor Jeremy Avigad (Department of Philosophy and the Department of Mathematical Sciences, Carnegie Mellon University). This is the fourth lecture.
 Abstract
Computers are changing the way we do mathematics, as well as introducing new research agendas. Computational methods in mathematics, including symbolic and numerical computation and simulation, are by now familiar. These lectures will explore the way that "formal methods," based on formal languages and logic, can contribute to mathematics as well.
In the 19th century, George Boole argued that if we take mathematics to be the science of calculation, then symbolic logic should be viewed as a branch of mathematics: just as number theory and analysis provide means to calculate with numbers, logic provides means to calculate with propositions. Computers are, indeed, good at calculating with propositions, and there are at least two ways that this can be mathematically useful: first, in the discovery of new proofs, and, second, in verifying the correctness of existing ones.
The first goal generally falls under the ambit of "automated theorem proving" and the second falls under the ambit of "interactive theorem proving." There is no sharp distinction between these two fields, however, and the line between them is becoming increasingly blurry. In these lectures, I will provide an overview of both fields and the interactions between them, and speculate as to the roles they can play in mainstream mathematics.
I will aim to make the lectures accessible to a broad audience. The first lecture will provide a selfcontained overview. The remaining lectures are for the most part independent of one another, and will not rely on the first lecture.
 [Permanent event link]
 CARMA AND AMSI LECTURE SERIES
 Mathematical Logic and Philosophy
 Location: Room V206, Mathematics Building (Callaghan Campus) The University of Newcastle
 Time and Date: 3:00 pm, Fri, 15^{th} May 2015
 Download: Lecture Tour Flyer (424 KB)
 Four lectures by Professor Jeremy Avigad (Department of Philosophy and the Department of Mathematical Sciences, Carnegie Mellon University). This is the third lecture.
 Abstract
Computers are changing the way we do mathematics, as well as introducing new research agendas. Computational methods in mathematics, including symbolic and numerical computation and simulation, are by now familiar. These lectures will explore the way that "formal methods," based on formal languages and logic, can contribute to mathematics as well.
In the 19th century, George Boole argued that if we take mathematics to be the science of calculation, then symbolic logic should be viewed as a branch of mathematics: just as number theory and analysis provide means to calculate with numbers, logic provides means to calculate with propositions. Computers are, indeed, good at calculating with propositions, and there are at least two ways that this can be mathematically useful: first, in the discovery of new proofs, and, second, in verifying the correctness of existing ones.
The first goal generally falls under the ambit of "automated theorem proving" and the second falls under the ambit of "interactive theorem proving." There is no sharp distinction between these two fields, however, and the line between them is becoming increasingly blurry. In these lectures, I will provide an overview of both fields and the interactions between them, and speculate as to the roles they can play in mainstream mathematics.
I will aim to make the lectures accessible to a broad audience. The first lecture will provide a selfcontained overview. The remaining lectures are for the most part independent of one another, and will not rely on the first lecture.
 [Permanent event link]
 CARMA AND AMSI LECTURE SERIES
 Mathematical Logic and Philosophy
 Location: Room V206, Mathematics Building (Callaghan Campus) The University of Newcastle
 Dates: Fri, 8^{th} May 2015  Fri, 8^{th} May 2015
 Download: Lecture Tour Flyer (424 KB)
 Four lectures by Professor Jeremy Avigad (Department of Philosophy and the Department of Mathematical Sciences, Carnegie Mellon University). This session includes two of the four lectures.
 Abstract
Computers are changing the way we do mathematics, as well as introducing new research agendas. Computational methods in mathematics, including symbolic and numerical computation and simulation, are by now familiar. These lectures will explore the way that "formal methods," based on formal languages and logic, can contribute to mathematics as well.
In the 19th century, George Boole argued that if we take mathematics to be the science of calculation, then symbolic logic should be viewed as a branch of mathematics: just as number theory and analysis provide means to calculate with numbers, logic provides means to calculate with propositions. Computers are, indeed, good at calculating with propositions, and there are at least two ways that this can be mathematically useful: first, in the discovery of new proofs, and, second, in verifying the correctness of existing ones.
The first goal generally falls under the ambit of "automated theorem proving" and the second falls under the ambit of "interactive theorem proving." There is no sharp distinction between these two fields, however, and the line between them is becoming increasingly blurry. In these lectures, I will provide an overview of both fields and the interactions between them, and speculate as to the roles they can play in mainstream mathematics.
I will aim to make the lectures accessible to a broad audience. The first lecture will provide a selfcontained overview. The remaining lectures are for the most part independent of one another, and will not rely on the first lecture.
 [Permanent event link]
 CARMA SEMINAR
 Speaker: Alexander Fish, School of Mathematics and Statistics, The University of Sydney
 Title: Ergodic theorems for amenable groups
 Location: Room V205, Mathematics Building (Callaghan Campus) The University of Newcastle
 Time and Date: 4:00 pm, Thu, 23^{rd} Apr 2015
 Abstract:
We will talk on the validity of the mean ergodic theorem along left Følner
sequences in a countable amenable group G. Although the weak ergodic theorem always holds
along any left Følner sequence in G, we will provide examples where the mean ergodic theorem fails
in quite dramatic ways. On the other hand, if G does not admit any ICC quotients, e.g. if G is
virtually nilpotent, then we will prove that the mean ergodic theorem does indeed hold along any left
Følner sequence.
Based on the joint work with M. Bjorklund (Chalmers).
 [Permanent event link]
 CARMA SEMINAR
 Speaker: Ernst Stephan, Insitut fur Angewandte Mathematik (IfAM), Leibniz Universitat Hannover
 Title: hpBEM for frictional contact problems in linear elasticity
 Location: Room V205, Mathematics Building (Callaghan Campus) The University of Newcastle
 Time and Date: 4:00 pm, Tue, 17^{th} Mar 2015
 Abstract:
A mixed formulation for a Tresca frictional contact problem in linear elasticity is considered in the context of boundary integral equations, which is later extended to Coulomb friction. The discrete Lagrange multiplier, an approximation of the surface traction on the contact boundary part, is a linear combination of biorthogonal basis functions. The biorthogonality allows to rewrite the variational inequality constraints as a simple set of complementary problems. Thus, enabling an efficient application of a semismooth Newton solver for the discrete mixed problems. Typically, the solution of frictional contact problems is of reduced regularity at the interface between contact to noncontact and from stick to slip. To identify the a priori unknown locations of these interfaces a posteriori error estimations of residual and hierarchical type are introduced. For a stabilized version of our mixed formulation (with the Poincare Steklov operator) we present also a priori estimates for the solution. Numerical results show the applicability of the error estimators and the superiority of hpadaptivity compared to low order uniform and adaptive approaches.
Ernst Stephan is a visitor of Bishnu Lamichhane.
 [Permanent event link]
 CARMA SEMINAR
 Location: Room V206, Mathematics Building (Callaghan Campus) The University of Newcastle
 Dates: Thu, 4^{th} Dec 2014  Thu, 4^{th} Dec 2014
 Talks by RHD students who will be presenting at the AustMS conference in Melbourne the following week.
 Speaker: Cameron Rogers, School of Mathematical and Physical Sciences, The University of Newcastle
 Title: Using Random walks to estimate the shape of Folner Sets
 Abstract for Using Random walks to estimate the shape of Folner Sets:
(Groups & Dynamics Special Session)
 Speaker: Ben Carter, The University of Newcastle
 Title: Adaptive assessment for differing maths backgrounds?
 Abstract for Adaptive assessment for differing maths backgrounds?:
(Maths Education Special Session)
 Speaker: Ohad Giladi, CARMA, The University of Newcastle
 Title: Small ball estimates for quasi norms
 Abstract for Small ball estimates for quasi norms:
(Operator Algebra/ Functional Analysis Special Session)
 [Permanent event link]
 CARMA SEMINAR
 Speaker: Nathan Clisby, The University of Melbourne
 Title: Monte Carlo simulation of selfavoiding walks
 Location: Room V205, Mathematics Building (Callaghan Campus) The University of Newcastle
 Time and Date: 4:00 pm, Thu, 23^{rd} Oct 2014
 Abstract:
Selfavoiding walks are a widely studied model of polymers, which are defined as walks on a lattice where each successive step visits a neighbouring site, provided the site has not already been visited. Despite the apparent simplicity of the model, it has been of much interest to statistical mechanicians and probabilists for over 60 years, and many important questions about it remain open.
One of the most powerful methods to study selfavoiding walks is Monte Carlo simulation. I'll give an overview of the historical developments in this field, and will explain what ingredients are needed for a good Monte Carlo algorithm. I'll then describe how recent progress has allowed for the efficient simulation of truly long walks with many millions of steps. Finally, I'll discuss whether lessons we've learned from simulating selfavoiding walks may be applicable to a wide range of Markov chain Monte Carlo simulations.
 [Permanent event link]
 CARMA SEMINAR
 Speaker: Paul Vrbik, School of Mathematical and Physical Sciences, The University of Newcastle
 Title: Computer Algebra : A Retrospective
 Location: Room V205, Mathematics Building (Callaghan Campus) The University of Newcastle
 Time and Date: 4:00 pm, Thu, 16^{th} Oct 2014
 Abstract:
We discuss the genesis of symbolic computation, its deployment into computer algebra systems, and the applications of these systems in the modern era.
We will pay special attention to polynomial system solvers and highlight the problems that arise when considering nonlinear problems. For instance, forgetting about actually solving, how does one even represent infinite solution sets?
 [Permanent event link]
 CARMA SEMINAR
 Speaker: Prof George Willis, CARMA, The University of Newcastle
 Title: Operators on the padic analogue of Hilbert space
 Location: Room V205, Mathematics Building (Callaghan Campus) The University of Newcastle
 Time and Date: 4:00 pm, Thu, 21^{st} Aug 2014
 Abstract:
The restricted product over $X$ of copies of the $p$adic numbers $\mathbb{Q}_p$, denoted $\mathbb{Q}_p(X)$, is selfdual and is the natural $p$adic analogue of Hilbert space. The additive group of this space is locally compact and the continuous endomorphisms of the group are precisely the continuous linear operators on $\mathbb{Q}_p(X)$.
Attempts to develop a spectral theory for continuous linear operators on $\mathbb{Q}_p(X)$ will be described at an elementary level. The Berkovich spectral theory over nonArchimedean fields will be summarised and the spectrum of the linear operator $T$ compared with the scale of $T$ as an endomorphism of $(\mathbb{Q}_p(X),+)$.
The original motivation for this work, which is joint with Andreas Thom (Leipzig), will also be briefly discussed. A certain result that holds for representations of any group on a Hilbert space, proved by operator theoretic methods, can only be proved for representations of sofic groups on $\mathbb{Q}_p(X)$ and it is thought that the difficulty might lie with the lack of understanding of linear operators on $\mathbb{Q}_p(X)$ rather than with nonsofic groups.
 [Permanent event link]
 CARMA SEMINAR
 Speaker: Laura Ciobanu, University of Neuchatel
 Title: Equations in groups
 Location: Room V206, Mathematics Building (Callaghan Campus) The University of Newcastle
 Time and Date: 4:00 pm, Thu, 7^{th} Aug 2014
 Abstract:
The Diophantine Problem in group theory can be stated as: is it
algorithmically decidable whether an equation whose coefficients are
elements of a given group has at least one solution in that group?
The talk will be a survey on this topic, with emphasis on what is known
about solving equations in free groups. I will also present some of the
algebraic geometry over groups developed in the last 20 years, and the
connections to logic and geometry. I will conclude with results concerning the
asymptotic behavior of satisfiable homogeneous equations in surface groups.
 [Permanent event link]
 CARMA SEMINAR
 Speaker: Simon Smith, University of Western Australia
 Title: Infinite discrete primitive permutation groups
 Location: Room V206, Mathematics Building (Callaghan Campus) The University of Newcastle
 Time and Date: 4:00 pm, Thu, 17^{th} Jul 2014
 Abstract:
Usually, when we want to study permutation groups, we look first at the primitive permutation groups (transitive groups in which point stabilizers are maximal); in the finite case these groups are the basic building blocks from which all finite permutation groups are comprised. Thanks to the seminal O'Nan—Scott Theorem and the Classification of the Finite Simple Groups, the structure of finite primitive permutation groups is broadly known.
In this talk I'll describe a new theorem of mine which extends the O'Nan—Scott Theorem to a classification of all primitive permutation groups with finite point stabilizers. This theorem describes the structure of these groups in terms of finitely generated simple groups.
 [Permanent event link]
 CARMA SEMINAR
 Speaker: Prof. Sarah Rees, Mathematics and Statistics, Newcastle University
 Title: When Artin groups are sufficiently large...
 Location: Room V206, Mathematics Building (Callaghan Campus) The University of Newcastle
 Access Grid Venue: TBC
 Time and Date: 1:30 pm, Mon, 14^{th} Jul 2014
 Abstract:
(see PDF)
 Download: Seminar abstract (74 KB)
 Via AGR from UWS
 [Permanent event link]
 CARMA SEMINAR
 Speaker: Assoc Prof Murray Elder, CARMA, The University of Newcastle
 Title: An algebraic generating function for permutations generated by a stack of depth 2 and infinite stack in series
 Location: Room V205, Mathematics Building (Callaghan Campus) The University of Newcastle
 Time and Date: 4:00 pm, Wed, 14^{th} May 2014
 Abstract:
This is joint work with Geoffrey Lee.
The set of permutations generated by a passing an ordered sequence through a stack of depth 2 followed by an infinite stack in series was shown to be finitely based by Elder in 2005. In this new work we obtain an algebraic generating function for this class, by showing it is in bijection with an unambiguous contextfree grammar.
 [Permanent event link]
 CARMA SEMINAR
 Speaker: Mr Chris Banks, CARMA, The University of Newcastle
 Title: On simple groups acting on trees
 Location: Room V205, Mathematics Building (Callaghan Campus) The University of Newcastle
 Time and Date: 4:00 pm, Wed, 23^{rd} Apr 2014
 Abstract:
In this talk I will present a general method of finding simple groups acting on trees. This process, beginning with any group $G$ acting on a tree, produces more groups known as the $k$closures of $G$. I will use several examples to highlight the versatility of this method, and I will discuss the properties of the $k$closures that allow us to find abstractly simple groups.
 [Permanent event link]
 CARMA SEMINAR
 Speaker: Victoria Stodden, Department of Statistics, Columbia University
 Title: Reproducibility in Experimental Mathematics
 Location: Room V206, Mathematics Building (Callaghan Campus) The University of Newcastle
 Time and Date: 3:00 pm, Fri, 28^{th} Mar 2014
 Abstract:
New questions regarding the reliability and verifiability of scientific findings are emerging as computational methods are being increasingly used in research. In this talk I will present a framework for incorporating computational research into the scientific method, namely standards for carrying out and disseminating research to facilitate reproducibility. I will present some recent empirical results on data and code publication; the pilot project http://ResearchCompendia.org for linking data and codes to published results and validating findings; and the "Reproducible Research Standard" for ensuring the distribution of legally usable data and code. If time permits, I will present preliminary work on assessing the reproducibility of published computational findings based on the 2012 ICERM workshop on Reproducibility in Computational and Experimental Mathematics report [1]. Some of this research is described in my forthcoming coedited books "Implementing Reproducible Research" and "Privacy, Big Data, and the Public Good."
[1] D. H. Bailey, J. M. Borwein, Victoria Stodden "Set the Default to 'Open'," Notices of the AMS, June/July 2013.
 [Permanent event link]
 CARMA SEMINAR
 Speaker: Xian'an Jin, School of Mathematics, Xiamen University
 Title: DNA and protein polyhedral links
 Location: Room V206, Mathematics Building (Callaghan Campus) The University of Newcastle
 Time and Date: 3:00 pm, Mon, 10^{th} Feb 2014
 Abstract:
Polyhedral links, interlinked and interlocked architectures, have been proposed for the description and characterization of DNA and protein polyhedra. Chirality is a very important feature for biomacromolecules. In this talk, we discuss the topological chirality of a type of DNA polyhedral links constructed by the strategy of "npoint stars and a type of protein polyhedral links constructed by "threecross curves" covering. We shall ignore DNA sequence and use the orientation of the 2 backbone strands of the dsDNA to orient DNA polyhedral links, thus consider DNA polyhedral links as oriented links with antiparallel orientations. We shall ignore protein sequence and view protein polyhedral links as unoriented ones. It is well known that there is a correspondence between alternating links and plane graphs. We prove that links corresponding to bipartite plane graphs have antiparallel orientations, and under these orientations, their writhes are not zero. As a result, the type of righthanded double crossover 4turn DNA polyhedral links are topologically chiral. We also prove that the unoriented link corresponding to a connected, even, bipartite plane graph has selfwrithe 0 and using the Jones polynomial we present a criterion for chirality of unoriented alternating links with selfwrithe 0. By applying this criterion we obtain that 3regular protein polyhedral links are also topologically chiral. Topological chirality always implies chemical chirality, hence the corresponding DNA and protein polyhedra are all chemically chiral. Our chiral criteria may be used to detect the topological chirality of more complicated DNA and protein polyhedral links to be synthesized by chemists and biologists in the future.
 [Permanent event link]
 CARMA SEMINAR
 Speaker: Liangjin Yao, CARMA, The University of Newcastle
 Title: Characterizations of ultramaximally monotone operators
 Location: Room V205, Mathematics Building (Callaghan Campus) The University of Newcastle
 Time and Date: 4:30 pm, Mon, 2^{nd} Dec 2013
 Abstract:
In this talk, we provide some characterizations of ultramaximally monotone operators. We establish the BrezisHaraux condition in the setting of a general Banach space. We also present some characterizations of reflexivity of a Banach space by a linear continuous ultramaximally monotone operator.
Joint work with Jon Borwein.
 [Permanent event link]
 CARMA SEMINAR
 Speaker: Assoc Prof Murray Elder, CARMA, The University of Newcastle
 Title: A Metropolis Markov Chain algorithm to sample trivial words and compute cogrowth in finitely generated groups; or  F is not amenable.
 Location: Room V205, Mathematics Building (Callaghan Campus) The University of Newcastle
 Time and Date: 4:00 pm, Thu, 21^{st} Nov 2013
 Abstract:
In this talk I will describe an algorithm to do a random walk in the space of all words equal to the identity in a finitely presented group. We prove that the algorithm samples from a well defined distribution, and using the distribution we can find the expected value for the mean length of a trivial word. We then use this information to estimate the cogrowth of the group. We ran the algorithm on several examples  where the cogrowth series in known exactly our results are in agreement with the exact results. Running the algorithm on Thompson's group $F$, we see behaviour consistent with the hypothesis that $F$ is not amenable.
 [Permanent event link]
 CARMA SEMINAR
 Speaker: Alexander Fish, School of Mathematics and Statistics, The University of Sydney
 Title: Product set phenomena for countable groups
 Location: Room V129, Mathematics Building (Callaghan Campus) The University of Newcastle
 Time and Date: 4:00 pm, Thu, 7^{th} Nov 2013
 Abstract:
We analyse local combinatorial structure in product sets of two subsets of a countable group which are "large" with respect to certain classes (not necessarily invariant) means on the group. As an example of such phenomenon, we can mention the result by Bergelson, Furstenberg and Weiss which says that the sumset of two sets of positive density in integers contains locally an almostperiodic set. In this theorem, large sets are the sets of positive density, and a combinatorial structure is an almost periodic set.
 [Permanent event link]
 CARMA SEMINAR
 Speaker: Hanna Kokko, unknown or leave blank,
 Title: Is Mother Nature shortsighted?
 Location: Room V129, Mathematics Building (Callaghan Campus) The University of Newcastle
 Time and Date: 4:00 pm, Thu, 24^{th} Oct 2013
 Abstract:
Popular accounts of evolution typically create an expectation that populations become ever better adapted over time, and some formal treatments of evolutionary processes suggest this too. However, such analyses do not highlight the fact that competition with conspecics has negative populationlevel consequences too, particularly when individuals invest in success in zerosum games. My own work is at the interface of theoretical biology and empirical data, and I will discuss several examples where an adaptive evolutionary process leads to something that appears silly from the population point of view, including a heightened risk of extinction in the Gouldian finch, reduced productivity of species in which males do not participate in parental care, and deterministic extinction of local populations in systems that feature sexual parasitism.
 [Permanent event link]
 CARMA SEMINAR
 Speaker: Kieran Larkin, Nontrivialzeros Research
 Title: Phase in Imaging
 Location: Room V129, Mathematics Building (Callaghan Campus) The University of Newcastle
 Time and Date: 3:30 pm, Mon, 26^{th} Aug 2013
 Abstract:
Image processing research is dominated, to a considerable degree, by linearadditive models of images. For example, wavelet decompositions are very popular both with experimentalists and theoreticians primarily because of their neatly convergent properties. Fourier and orthogonal series decompositions are also popular in applications, as well as playing an important part in the analysis of wavelet methods.
Multiplicative decomposition, on the other hand, has had very little use in image processing. In 1D signal processing and communication theory it has played a vital part (amplitude, phase, and frequency modulations of communications theory especially).
In many cases 2D multiplicative decompositions have just been too hard to formulate or expand. Insurmountable problems (divergences) often occur as the subtle consequences of unconscious errors in the choice of mathematical structure. In my work over the last 17 years I've seen how to overcome some of the problems in 2D, and the concept of phase is a central, recurring theme. But there is still so much more to be done in 2D and higher dimensions.
This talk will be a whirlwind tour of some main ideas and applications of phase in imaging.
 [Permanent event link]
 CARMA SEMINAR
 Speaker: Edward Saff, Vanderbilt University
 Title: Minimal Energy and Maximal Polarization
 Location: Room V129, Mathematics Building (Callaghan Campus) The University of Newcastle
 Time and Date: 4:00 pm, Thu, 25^{th} Jul 2013
 Abstract:
This talk deals with problems that are asymptotically related to bestpacking and bestcovering. In particular, we discuss how to efficiently generate N points on a ddimensional manifold that have the desirable qualities of wellseparation and optimal order covering radius, while asymptotically having a prescribed distribution. Even for certain small numbers of points like N=5, optimal arrangements with regard to energy and polarization can be a challenging problem.
 [Permanent event link]
 CARMA SEMINAR
 Speaker: Dr Bishnu Lamichhane, CARMA, The University of Newcastle
 Title: Efficient Finite Element Methods for ReissnerMindlin, Biharmonic and Thin Plate Equations
 Location: Room V129, Mathematics Building (Callaghan Campus) The University of Newcastle
 Time and Date: 4:00 pm, Thu, 18^{th} Jul 2013
 Abstract:
The finite element method has become the most powerful approach in approximating solutions of partial differential equations arising in modern engineering and physical applications. We present some efficient finite element methods for ReissnerMindlin, biharmonic and thin plate equations.
In the first part of the talk I present some applied partial differential equations, and introduce the finite element method using the biharmonic equation. In the second part of the talk I will discuss about the finite element method for ReissnerMindlin, biharmonic and thin plate spline equations in a unified framework.
 [Permanent event link]
 CARMA SEMINAR
 Speaker: Prof George Willis, CARMA, The University of Newcastle
 Title: The 21st birthday of the Factoring Lemma
 Location: Room V129, Mathematics Building (Callaghan Campus) The University of Newcastle
 Time and Date: 4:00 pm, Thu, 20^{th} Jun 2013
 Abstract:
You are invited to a celebration of the 21st anniversary of the Factoring Lemma. This lemma was the key to solving some longstanding open problems, and was the starting point of an investigation of totally disconnected, locally compact groups that has ensued over the last 20 years. In this talk, the life of the lemma will described from its conception through to a very recent strengthening of it. It will be described at a technical level, as well as viewed through its relationships with topology, geometry, combinatorics, algebra, linear algebra and research grants.
A birthday cake will be served afterwards.
Please make donations to the Mathematics Prize Fund in lieu of gifts.
 [Permanent event link]
 CARMA SEMINAR
 Speaker: Assoc Prof Murray Elder, CARMA, The University of Newcastle
 Title: Cgraph automatic groups
 Location: Room V129, Mathematics Building (Callaghan Campus) The University of Newcastle
 Time and Date: 4:00 pm, Thu, 16^{th} May 2013
 Abstract:
Graph automatic groups are an extension of the notion of an automatic group, introduced by Kharlampovich, Khoussainov and Miasnikov in 2011, with the intention to capture a wider class of groups while preserving computational properties such as having quadratic time word problem. We extend the notion further by replacing regular with more general language classes. We prove that nonsolvable BaumslagSolitar groups are (context free)graph automatic, (context sensitive)graph automatic implies a contextsensitive word problem and conversely groups with context sensitive word problem are (context sensitive)automatic. Finally an obstruction to (context sensitive)graph automatic implying polynomial time word problem is given.
This is joint work with Jennifer Taback, Bowdoin College.
 [Permanent event link]
 CARMA SEMINAR
 Speaker: Dr Jeff Hogan, CARMA, The University of Newcastle
 Title: Prolate spheroidal wavefunctions II
 Location: Room V129, Mathematics Building (Callaghan Campus) The University of Newcastle
 Time and Date: 4:00 pm, Thu, 2^{nd} May 2013
 Abstract:
The classical prolate spheroidal wavefunctions (prolates) arise when solving the Helmholtz equation by separation of variables in prolate spheroidal coordinates. They interpolate between Legendre polynomials and Hermite functions. In a beautiful series of papers published in the Bell Labs Technical Journal in the 1960's, they were rediscovered by Landau, Slepian and Pollak in connection with the spectral concentration problem. After years spent out of the limelight while wavelets drew the focus of mathematicians, physicists and electrical engineers, the popularity of the prolates has recently surged through their appearance in certain communication technologies. In this talk we outline some developments in the sampling theory of bandlimited signals that employ the prolates, and the construction of bandpass prolate functions.
This is joint work with Joe Lakey (New Mexico State University)
 [Permanent event link]
 CARMA SEMINAR
 Speaker: Malte Peter, Institute of Mathematics, University of Augsburg
 Title: A multiscale approach to reactiondiffusion processes in domains with microstructure
 Location: Room V129, Mathematics Building (Callaghan Campus) The University of Newcastle
 Time and Date: 4:00 pm, Thu, 21^{st} Mar 2013
 Abstract:
Reactiondiffusion processes occur in many materials with microstructure such as biological cells, steel or concrete. The main difficulty in modelling and simulating accurately such processes is to account for the fine microstructure of the material. One method of upscaling multiscale problems, which has proven reliable for obtaining feasible macroscopic models, is the method of periodic homogenisation.
The talk will give an introduction to multiscale modelling of chemical mechanisms in domains with microstructure as well as to the method of periodic homogenisation. Moreover, a few aspects of solving the resulting systems of equations numerically will also be discussed.
 [Permanent event link]
 CARMA SEMINAR
 Speaker: Florian Luca, Centro de Ciencias Matemáticas, Universidad Nacional Autónoma de México
 Title: Linear independence of certain Lambert series
 Location: Room V206, Mathematics Building (Callaghan Campus) The University of Newcastle
 Time and Date: 3:00 pm, Wed, 13^{th} Mar 2013
 Abstract:
We prove that if $q\ne0,\pm1$ and $\ell\ge1$ are fixed
integers, then the numbers
$$
1, \quad \sum_{n=1}^\infty\frac{1}{q^n1},
\quad \sum_{n=1}^\infty\frac{1}{q^{n^2}1}, \quad \dots,
\quad \sum_{n=1}^\infty\frac{1}{q^{n^\ell}1}
$$
are linearly independent over $\mathbb{Q}$. This generalizes a result
of Erdős who treated the case $\ell=1$.
The method is based on the original approaches of Chowla and
Erdős, together with some results about primes in arithmetic
progressions with large moduli of Ahlford, Granville and Pomerance.
This is joint work with Yohei Tachiya.
 [Permanent event link]
 CARMA SEMINAR
 Speaker: Kevin Hare, University of Waterloo
 Title: An explicit counterexample to the LagariasWang finiteness conjecture
 Location: Room V129, Mathematics Building (Callaghan Campus) The University of Newcastle
 Time and Date: 4:00 pm, Thu, 28^{th} Feb 2013
 Abstract:
The joint spectral radius of a finite set of real $d \times d$ matrices is defined to be the maximum possible exponential rate of growth of long products of matrices drawn from that set. A set of matrices is said to have the finiteness property if there exists a periodic product which achieves this maximal rate of growth. J. C. Lagarias and Y. Wang conjectured in 1995 that every finite set of real $d \times d$ matrices satisfies the finiteness property. However, T. Bousch and J. Mairesse proved in 2002 that counterexamples to the finiteness conjecture exist, showing in particular that there exists a family of pairs of $2 \times 2$ matrices which contains a counterexample. Similar results were subsequently given by V. D. Blondel, J. Theys and A. A. Vladimirov and by V. S. Kozyakin, but no explicit counterexample to the finiteness conjecture was given. This talk will discuss an explicit counterexample to this conjecture.
 [Permanent event link]
 CARMA SEMINAR
 Speaker: José Burillo, Departament de Matemàtica Aplicada IV, Universitat Politècnica de Catalunya
 Title: Distortion and metric estimates for finitely generated groups
 Location: Room V129, Mathematics Building (Callaghan Campus) The University of Newcastle
 Time and Date: 3:00 pm, Fri, 22^{nd} Feb 2013
 Abstract:
After Gromov's work in the 1980s, the modern approach to
studying infinite groups is from the geometric point of view, seeing
them as metric spaces and using geometric concepts. One of these is the
concept of distortion of a subgroup in a group. Here we will give the
definition and some examples of distorted and nondistorted subgroups and
some recent results on them. The main tools used to establish these
results are quasimetrics or metric estimates, which are quantities
which differ from the distance by a multiplicative constant, but which
still capture the concept enough to understand distortion.
 [Permanent event link]
 CARMA SEMINAR
 Speaker: Mr Dmitriy Drusvyatskiy, School of Operations Research and Information Engineering, Cornell University
 Title: Active sets, steepest descent, and smooth approximations of functions
 Location: Room V129, Mathematics Building (Callaghan Campus) The University of Newcastle
 Time and Date: 4:00 pm, Thu, 21^{st} Feb 2013
 Abstract:
Three ideas  active sets, steepest descent, and smooth approximations of functions  permeate nonsmooth optimization. I will give a fresh perspective on these concepts, and illustrate how many results in these areas can be strengthened in the semialgebraic setting.
This is joint work with A.D. Ioffe (Technion), A.S. Lewis (Cornell),
and M. Larsson (EPFL).
 [Permanent event link]
 CARMA SEMINAR
 Speaker: Kevin Hare, University of Waterloo
 Title: Stolarsky's Conjecture and the sum of digits function
 Location: Room V129, Mathematics Building (Callaghan Campus) The University of Newcastle
 Time and Date: 4:00 pm, Thu, 7^{th} Feb 2013
 Abstract:
Let $s_q(n)$ be the sum of the $q$ary digits of $n$. For example $s_{10}(1729) = 1 + 7 + 2 + 9 = 19$. It is known what $s_q(n)$ looks like "on average". It can be shown that $s_q(n^h)$ looks $h$ times bigger "on average". This raises the question: is the ratio of these two things $h$ on average? In this talk we will give some history on the sum of digits function, and will give a proof of one of Stolarsky's conjecture concerning the minimal values of the ratio of $s_q(n)$ and $s_q(n^h)$.
 [Permanent event link]
 CARMA SEMINAR
 Speaker: Tara Brough, University of St Andrews
 Title: Automaton Semigroup Constructions
 Location: Room V129, Mathematics Building (Callaghan Campus) The University of Newcastle
 Time and Date: 4:00 pm, Thu, 24^{th} Jan 2013
 Abstract:
Automaton semigroups are a natural generalisation of the automaton groups introduced by Grigorchuk and others in the 1980s as examples of groups having various 'exotic' properties. In this talk I will give a brief introduction to automaton semigroups, and then discuss recent joint work with Alan Cain on the extent to which the class of automaton semigroups is closed under certain semigroup constructions (free products and wreath products).
 [Permanent event link]
 CARMA SEMINAR
 Speaker: Dr Victoria MartínMárquez, Department of Mathematical Analysis, Universidad de Sevilla
 Title: On Iterative Methods for Solving Convex Feasibility Problems and applications
 Location: Room V206, Mathematics Building (Callaghan Campus) The University of Newcastle
 Access Grid Venue: UNewcastle [ENQUIRIES]
 Time and Date: 4:00 pm, Thu, 6^{th} Dec 2012
 Abstract:
Many problems in diverse areas of mathematics and modern
physical sciences can be formulated as a Convex Feasibility Problem,
consisting of finding a point in the intersection of finitely many
closed convex sets. Two other related problems are the Split Feasibility
Problem and the MultipleSets Split Feasibility Problem, both very
useful when solving inverse problems where constraints are imposed in
the domain as well as in the range of a linear operator. We present some
recent contributions concerning these problems in the setting of Hilbert
spaces along with some numerical experiments to illustrate the
implementation of some iterative methods in signal processing.
 [Permanent event link]
 CARMA SEMINAR
 Location: Room V129, Mathematics Building (Callaghan Campus) The University of Newcastle
 Time and Date: 2:00 pm, Tue, 4^{th} Dec 2012
 University of Newcastle participants in the 36th Australasian Conference on Combinatorial Mathematics and Combinatorial Computing will be giving practice runs of their 20 minute conference talks. If you want to give a talk, let Mirka Miller know (mirka.miller@newcastle.edu.au) and she will add you to the schedule. If you wish to come and listen, feel free to drop in.
 [Permanent event link]
 CARMA SEMINAR
 Speaker: Prof. Ljiljana Brankovic, School of Electrical Engineering and Computer Science, The University of Newcastle
 Title: Combining two worlds: Parameterised Approximation for Vertex Cover
 Location: Room V129, Mathematics Building (Callaghan Campus) The University of Newcastle
 Time and Date: 4:00 pm, Thu, 29^{th} Nov 2012
 Abstract:
Parameterised approximation is a relatively new but growing field of interest. It merges two ways of dealing with NPhard optimisation problems, namely polynomial approximation and exact parameterised (exponentialtime) algorithms.
We explore opportunities for parameterising constant factor approximation algorithms for vertex cover, and we provide a simple algorithm that works on any approximation ratio of the form $\frac{2l+1}{l+1}$, $l=1,2,\dots$, and has complexity that outperforms previously published algorithms by Bourgeois et al. based on sophisticated exact parameterised algorithms. In particular, for $l=1$ (factor$1.5$ approximation) our algorithm runs in time $\text{O}^*(\text{simpleonefiveapproxbase}^k)$, where parameter $k \leq \frac{2}{3}\tau$, and $\tau$ is the size of a minimum vertex cover.
Additionally, we present an improved polynomialtime approximation algorithm for graphs of average degree at most four and a limited number of vertices with degree less than two.
 [Permanent event link]
 CARMA SEMINAR
 Speaker: Prof Jeff Linderoth, Department of Industrial and Systems Engineering, University of WisconsinMadison
 Title: Multiterm Relaxations for Multilinear Programs
 Location: Room V206, Mathematics Building (Callaghan Campus) The University of Newcastle
 Access Grid Venue: UNewcastle [ENQUIRIES]
 Time and Date: 4:00 pm, Thu, 22^{nd} Nov 2012
 Abstract:
Multilinear functions appear in many global optimization problems, including reformulated quadratic and polynomial optimization problems. There is a extended formulation for the convex hull of the graph of a multilinear function that requires the use of an exponential number of variables. Relying on this result, we study an approach that generates relaxations for multiple terms simultaneously, as opposed to methods that relax the nonconvexity of each term individually. In some special cases, we are able to establish analytic bounds on the ratio of the strength of the termbyterm and convex hull relaxations. To our knowledge, these are the first approximationratio results for the strength of relaxations of global optimization problems. The results lend insight into the design of practical (nonexponentially sized) relaxations. Computations demonstrate that the bounds obtained in this manner are competitive with the wellknown semidefinite programming based bounds for these problems.
Joint work with Jim Luedtke, University of WisconsinMadison, and Mahdi Namazifar, now with Opera Solutions.
 [Permanent event link]
 CARMA SEMINAR
 Speaker: Mr Nick Davis, Department of Mathematics and Statistics, The University of Melbourne
 Title: Automata groups and their selfsimilarity graphs
 Location: Room V129, Mathematics Building (Callaghan Campus) The University of Newcastle
 Time and Date: 4:00 pm, Thu, 15^{th} Nov 2012
 Abstract:
Automata groups are a class of groups generated by recursively defined automorphisms of a regular rooted tree. Associated to each automata group is an object known as the selfsimilarity graph. Nekrashevych showed that in the case where the group satisfies a natural condition known as contracting, the selfsimilarity graph is Gromovhyperbolic and has boundary homeomorphic to the limit space of the group action. I will talk about selfsimilarity graphs of automata groups that do not satisfy the contracting condition.
 [Permanent event link]
 CARMA SEMINAR
 Speaker: Mr Meksianis Ndii, School of Mathematical and Physical Sciences, The University of Newcastle
 Title: Wolbachia intervention in reducing dengue transmission
 Location: Room V129, Mathematics Building (Callaghan Campus) The University of Newcastle
 Time and Date: 4:00 pm, Thu, 8^{th} Nov 2012
 Abstract:
Infecting aedes aegypti with Wolbachia has been proposed as an alternative in reducing dengue transmission. If Wolbachiainfected mosquitoes can invade and dominate the population of aedes aegypti mosquitoes, they can reduce dengue transmission. Cytoplasmic Incompatibility (CI) provides the reproductive advantage for Wolbachiainfected mosquitoes with which they can reproduce more and dominate the population. A mosquito population model is developed in order to determine the survival of Wolbachiainfected mosquiotes when they are released into the wild. The model has two physically stable realistic steady states. The model reveals that once the Wolbachiainfected mosquitoes survive, they ultimately dominate the population.
 [Permanent event link]
 CARMA SEMINAR
 Speaker: Assoc Prof Murray Elder, CARMA, The University of Newcastle
 Title: Totally disconnected groups from BaumslagSolitar groups
 Location: Room V129, Mathematics Building (Callaghan Campus) The University of Newcastle
 Time and Date: 4:00 pm, Thu, 20^{th} Sep 2012
 Abstract:
We consider the problem of characterising embeddings of an abstract group into totally disconnected locally compact (tdlc) groups. Specifically, for each pair of nonzero integers $m,n$ we construct a tdlc group containing the BaumslagSolitar group $BS(m,n)$ as a dense subgroup, and compute the scales of elements and flat rank of the tdlc group.
This is joint work with George Willis.
 [Permanent event link]
 CARMA SEMINAR
 Speaker: Mr Ian Searston, School of Mathematical and Physical Sciences, The University of Newcastle
 Title: Projection Algorithms in CAT(0) spaces
 Location: Room V129, Mathematics Building (Callaghan Campus) The University of Newcastle
 Time and Date: 4:00 pm, Thu, 6^{th} Sep 2012
 Abstract:
Recently the Alternating Projection Algorithm was extended into CAT(0) spaces. We will look at this and also current work on extending the Douglas Rachford Algorithm into CAT(0) spaces. By using CAT(0) spaces the underlying linear structure of the space is dispensable and this allows certain algorithms to be extended to spaces such as classical hyperbolic spaces, simply connected Riemannian manifolds of nonpositive curvature, Rtrees and Euclidean buildings.
 [Permanent event link]
 CARMA SEMINAR
 Speaker: Prof David Bailey, Berkeley, California
 Title: Normality and nonnormality of mathematical constants
 Location: Room V129, Mathematics Building (Callaghan Campus) The University of Newcastle
 Time and Date: 4:00 pm, Thu, 30^{th} Aug 2012
 Abstract:
Given a positive integer b, we say that a mathematical constant alpha is "bnormal" or "normal base b" if every mlong string of digits appears in the baseb expansion of alpha with precisely the limiting frequency 1/b^m. Although it is well known from measure theory that almost all real numbers are bnormal for all integers b > 1, nonetheless proving normality (or nonnormality) for specific constants, such as pi, e and log(2), has been very difficult.
In the 21st century, a number of different approaches have been attempted on this problem. For example, a recent study employed a Poisson model of normality to conclude that based on the first four trillion hexadecimal digits of pi, it is exceedingly unlikely that pi is not normal. In a similar vein, graphical techniques, in most cases based on the digitgenerated "random" walks, have been successfully employed to detect certain nonnormality in some cases.
On the analytical front, it was shown in 2001 that the normality of certain reals, including log(2) and pi (or any other constant given by a BBP formula), could be reduced to a question about the behavior of certain specific pseudorandom number generators. Subsequently normality was established for an uncountable class of reals (the "Stoneham numbers"), the simplest of which is: alpha_{2,3} = Sum_{n >= 0} 1/(3^n 2^(3^n)), which is provably normal base 2. Just as intriguing is a recent result that alpha_{2,3}, for instance, is provably NOT normal base 6. These results have now been generalized to some extent, although many open cases remain.
In this talk I will present an introduction to the theory of normal numbers, including brief mention of new graphical and statisticalbased techniques. I will then sketch a proof of the normality base 2 (and nonnormality base 6) of Stoneham numbers, then suggest some additional lines of research. Various parts of this research were conducted in collaboration with Richard Crandall, Jonathan and Peter Borwein, Francisco Aragon, Cristian Calude, Michael Dinneen, Monica Dumitrescu and Alex Yee.
 [Permanent event link]
 SIGMAOPT/CARMA SEMINAR
 Speaker: Laureate Prof Jon Borwein, CARMA, The University of Newcastle
 Title: Expectation integrals on fractal sets
 Location: Room V205, Mathematics Building (Callaghan Campus) The University of Newcastle
 Access Grid Venue: UNewcastle [ENQUIRIES]
 Time and Date: 3:00 pm, Mon, 13^{th} Aug 2012
 Abstract:
(Joint speakers, Jon Borwein and Michael Rose)
p>Using fractal selfsimilarity and functionalexpectation relations, the classical theory of box integrals is extended to encompass a new class of fractal “stringgenerated Cantor sets” (SCSs) embedded in unit hypercubes of arbitrary dimension. Motivated by laboratory studies on the distribution of brain synapses, these SCSs were designed for dimensional freedom: a suitable choice of generating string allows for finetuning the fractal dimension of the corresponding set. We also establish closed forms for certain statistical moments on SCSs and report various numerical results. The associated paper is at http://www.carma.newcastle.edu.au/jon/papers.html#PAPERS.
 (Joint talk with Michael Rose.)
 [Permanent event link]
 CARMA SEMINAR
 Speaker: Dr Alexander Plakhov, Center for Research and Development in Mathematics and Applications, University of Aveiro
 Title: Problems of optimal resistance in Newtonian aerodynamics
 Location: Room V129, Mathematics Building (Callaghan Campus) The University of Newcastle
 Time and Date: 3:00 pm, Thu, 5^{th} Jul 2012
 Abstract:
A body moves in a rarefied medium of resting particles and at the same
time very slowly rotates (somersaults). Each particle of the medium is reflected
elastically when hitting the body boundary (multiple reflections are possible).
The resulting resistance force acting on the body depends on the time; we are
interested in minimizing the timeaveraged value of resistance (which is called
$R$). The value $R(B)$ is well defined in terms of billiard in the complement of $B$,
for any bounded body $B \subset \mathbb{R}^d$, $d\geq 2$ with piecewise smooth boundary.
Let $C\subset\mathbb{R}^d$ be a bounded convex body and $C_1\subset C$ be another convex body
with $\partial C_1 \cap C=\varnothing$. It would be interesting to get an estimate for
$$R(C1_,C)= \inf_{C_1\subset B \subset C} R(B) .................. (1)$$
If $\partial C_1$ is close to $\partial C$, problem (1) can be referred to as minimizing the resistance
of the convex body $C$ by "roughening" its surface. We cannot solve problem (1);
however we can find the limit
$$\lim_{\text{dist}(\partial C_1,\partial C)\rightarrow 0} \frac{R(C_1,C)}{R(C)}. .................. (2) $$
It will be explained that problem (2) can be solved by reduction to a special
problem of optimal mass transportation, where the initial and final measurable
spaces are complementary hemispheres, $X=\{x=(x_1,...,x_d)\in S^{d1}: x_1\geq 0\}$
and $Y=\{x\in S^{d1}:x_1\leq 0\}$. The transportation cost is the squared distance,
$c(x,y)=\frac{1}{2}xy^2$, and the measures in $X$ and $Y$ are obtained from the $(d1)$dimensional
Lebesgue measure on the equatorial circle $\{x=(x_1,...,x_d):x\leq 1,x_1=0\}$ by
parallel translation along the vector $e_1=(1,0,...,0)$. Let $C(\nu)$ be
the total cost corresponding to the transport plan $\nu$ and let $\nu_0$ be the transport
plan generated by parallel translation along $e_1$; then the value $\frac{\inf C(\nu)}{C(\nu_0)}$ coincides
with the limit in (2).
Surprisingly, this limit does not depend on the body $C$ and depends only
on the dimension $d$. In particular, if $d=3$ ($d=2$), it equals (approximately) 0.96945 (0.98782). In other words, the resistance of a 3dimensional (2dimensional) convex body can be decreased by 3.05% (correspondingly, 1.22%)
at most by roughening its surface.
 [Permanent event link]
 CARMA SEMINAR
 Speaker: Dr Francisco Aragón Artacho, CARMA, The University of Newcastle
 Title: DouglasRachford: an algorithm that mysteriously solves sudokus and other nonconvex problems
 Location: Room V129, Mathematics Building (Callaghan Campus) The University of Newcastle
 Time and Date: 4:00 pm, Thu, 21^{st} Jun 2012
 Abstract:
The DouglasRachford algorithm is an iterative method for finding a point in the intersection of two (or more) closed sets. It is wellknown that the iteration (weakly) converges when it is applied to convex subsets of a Hilbert space. Despite the absence of a theoretical justification, the algorithm has also been successfully applied to various nonconvex practical problems, including finding solutions for the eight queens problem, or sudoku puzzles. In particular, we will show how these two problems can be easily modelled.
With the aim providing some theoretical explanation of the convergence in the nonconvex case, we have established a region of convergence for the prototypical nonconvex DouglasRachford iteration which finds a point on the intersection of a line and a circle. Previous work was only able to establish local convergence, and was ineffective in that no explicit region of convergence could be given.
PS: Bring your hardest sudoku puzzle :)
 Download: Talk slides (4.7 MB)
 [Permanent event link]
 CARMA SEMINAR
 Speaker: Prof A. Bass Bagayogo, Université de SaintBoniface
 Title: TBA
 Location: Room V129, Mathematics Building (Callaghan Campus) The University of Newcastle
 Time and Date: 4:00 pm, Tue, 12^{th} Jun 2012
 Abstract:
TBA
 [Permanent event link]
 CARMA SEMINAR
 Speaker: Dr Roslyn Hickson, School of Mathematical and Physical Sciences, The University of Newcastle
 Title: TB or not TB? in the Torres Strait region
 Location: Room V129, Mathematics Building (Callaghan Campus) The University of Newcastle
 Time and Date: 4:00 pm, Thu, 7^{th} Jun 2012
 Abstract:
There is a high prevalence of tuberculosis (TB) in Papua New Guinea (PNG), which is exacerbated by the presence of drugresistant TB strains and HIV infection. This is an important public health issue not only locally within PNG, but also in Australia due to the high crossborder traffic in the Torres Strait Island–Western Province (PNG) treaty region. A metapopulation model is used to evaluate the effect of varying control strategies in the region, and some initial costbenefit analysis figures are presented.
 [Permanent event link]
 CARMA SEMINAR
 Speaker: Prof Wal Wallis, Department of Mathematics, Southern Illinois University
 Title: Minimal Pancyclic Graphs
 Location: Room V129, Mathematics Building (Callaghan Campus) The University of Newcastle
 Time and Date: 1:00 pm, Tue, 5^{th} Jun 2012
 Abstract:
A graph on v vertices is called pancyclic if it contains cycles of every length from 3 to v. Obviously such graphs exist — the complete graph on v vertices is an example. We shall look at the question, what is the minimum number of edges in a pancyclic graph? Interestingly, this question was "solved", incorrectly, in 1978. A complete solution is not yet known.
 [Permanent event link]
 CARMA SEMINAR
 Speaker: Prof Martin Bunder, University of Wollongong
 Title: How I got into Logic via John Giles's course on Measure Theory
 Location: Room V129, Mathematics Building (Callaghan Campus) The University of Newcastle
 Time and Date: 4:00 pm, Thu, 24^{th} May 2012
 Abstract:
This involves (in prenonstandard analysis times) the development of a simple system of infinites and infinitesmals that help to clarify Cantor's Ternary Set, nonmeasurable sets and Lebesgue integration. The talk will include other memories as a maths student at Newcastle University College, Tighes Hill, from 1959 to 1961.
 [Permanent event link]
 CARMA SEMINAR
 Speaker: Joe Lakey, New Mexico State University
 Title: Time and Band Limiting
 Location: Room V129, Mathematics Building (Callaghan Campus) The University of Newcastle
 Time and Date: 4:00 pm, Thu, 17^{th} May 2012
 Abstract:
This talk will survey some of the classical and recent results concerning operators composed of a projection onto a compact set in time, followed by a projection onto a compact set in frequency. Such "time and bandlimiting" operators were studied by Landau, Slepian, and Pollak in a series of papers published in the Bell Systems Tech. Journal in the early 1960s identifying the eigenfunctions, providing eigenvalue estimates, and describing spaces of "essentially time and bandlimited signals."
Further progress on time and bandlimiting has been intermittent, but genuine recent progress has been made in terms of numerical analysis, sampling theory, and extensions to multiband signals, all driven to some extent by potential applications in communications. After providing an outline of the historical developments in the mathematical theory of time and bandlimiting, some details of the sampling theory and multiband setting will be given. Part of the latter represents joint work with Jeff Hogan and Scott Izu.
 [Permanent event link]
 CARMA SEMINAR
 Speaker: Karen Smilowitz, Industrial Engineering and Management Sciences, Northwestern University
 Title: Transportation and logistics models in nonprofit settings
 Location: Room V09, Mathematics Building (Callaghan Campus) The University of Newcastle
 Time and Date: 10:00 am, Fri, 11^{th} May 2012
 Abstract:
This talk will discuss opportunities and challenges related to the development and application of operations research techniques to transportation and logistics problems in nonprofit settings. Much research has been conducted on transportation and logistics problems in commercial settings where the goal is either to maximize profit or to minimize cost. Significantly less work has been conducted for nonprofit applications. In such settings, the objectives are often more difficult to quantify since issues such as equity and sustainability must be considered, yet efficient operations are still crucial. This talk will present several research projects that introduce new approaches tailored to the objectives and constraints unique to nonprofit agencies, which are often concerned with obtaining equitable solutions given limited, and often uncertain, budgets, rather than with maximizing profits.
This talk will assess the potential of operations research to address the problems faced by nonprofit agencies and attempt to understand why these problems have been understudied within the operations research community. To do so, we will ask the following questions: Are nonprofit operations problems rich enough for academic study? and Are solutions to nonprofit operations problems applicable to real communities?
 [Permanent event link]
 CARMA SEMINAR
 Speaker: Sergey Ajiev, University of NSW
 Title: Analysis on infinitedimensional spaces: from qualitative stability to quantitative
 Location: Room V129, Mathematics Building (Callaghan Campus) The University of Newcastle
 Time and Date: 4:00 pm, Thu, 3^{rd} May 2012
 Abstract:
Approximation theory is a classical part of the analysis of functions defined on an Euclidean space or its subset and the foundation of its applications, while the problems related to high or infinite dimensions create known challenges even in the setting of Hilbert spaces. The stability (uniform continuity) of a mapping is one of the traditional properties investigated in various branches of pure and applied mathematics and further applications in engineering. Examples include analysis of linear and nonlinear PDEs, (shortterm) prediction problems and decisionmaking and data evolution.
We describe the uniform approximation properties of the uniformly continuous mappings between the pairs of Banach and, occasionally, metric spaces from various wide parameterised and nonparameterised classes of spaces with or without the local unconditional structure in a quantitative manner. The striking difference with the finitedimensional setting is represented by the presence of Tsar'kov's phenomenon. Many tools in use are developed under the scope of our quasiEuclidean approach. Its idea seems to be relatively natural in light of the compressed sensing and distortion phenomena.
 [Permanent event link]
 CARMA SEMINAR
 Speaker: Dr Paul Leopardi, Australian National University
 Title: New constructions for Hadamard matrices
 Location: Room V129, Mathematics Building (Callaghan Campus) The University of Newcastle
 Time and Date: 4:30 pm, Thu, 26^{th} Apr 2012
 Abstract:
The talk will outline some topics associated with constructions for Hadamard matrices, in particular, a relatively simple construction, given by a sum of Kronecker products of ingredient matrices obeying certain conditions. Consideration of the structure of the ingredient matrices leads, on the one hand, to consideration of division algebras and Clifford algebras, and on the other hand, to searching for multisets of {1,1} ingredient matrices. Structures within the sets of ingredient matrices can make searching more efficent.
 Please note the start time.
 [Permanent event link]
 CARMA SEMINAR
 Location: Room V129, Mathematics Building (Callaghan Campus) The University of Newcastle
 Dates: Mon, 23^{rd} Apr 2012  Mon, 23^{rd} Apr 2012
12:001:00  Michael Coons (University of Waterloo) 
1:002:00  Claus Koestler (Aberystwyth University) 
2:003:00  Eric Mortenson (The University of Queensland) 
3:004:00  Ekaterina Shemyakova (University of Western Ontario) 
 [Permanent event link]
 CARMA SEMINAR
 Speaker: Darryn Bryant, The University of Queensland
 Title: Graph decomposition and the Oberwolfach problem
 Location: Room V129, Mathematics Building (Callaghan Campus) The University of Newcastle
 Time and Date: 4:00 pm, Thu, 12^{th} Apr 2012
 Abstract:
This will be an introductory talk which begins by describing the four colour theorem and finite projective planes in the setting of graph decompositions. A problem posed by Ringel at a graph theory meeting in Oberwolfach in 1967 will then be discussed. This problem is now widely known as the Oberwolfach Problem, and is a generalisation of a question asked by Kirkman in 1850. It concerns decompositions of complete graphs into isomorphic copies of spanning regular graphs of degree two.
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 CARMA SEMINAR
 Speaker: Graham White, The University of Sydney
 Title: Automorphisms of geometric structures associated to Coxeter groups
 Location: Room V129, Mathematics Building (Callaghan Campus) The University of Newcastle
 Time and Date: 4:00 pm, Thu, 5^{th} Apr 2012
 Abstract:
In this talk, we consider the automorphism groups of the Cayley graph with respect to the Coxeter generators and the Davis complex of an arbitrary Coxeter group. We determine for which Coxeter groups these automorphism groups are discrete. In the case where they are discrete, we express them as semidirect products of two obvious families of automorphisms. This extends a result of Haglund and Paulin.
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 CARMA SEMINAR
 Speaker: Ernst Stephan, Insitut fur Angewandte Mathematik (IfAM), Leibniz Universitat Hannover
 Title: hpadaptive DGFEM for Parabolic Obstacle Problems
 Location: Room V205, Mathematics Building (Callaghan Campus) The University of Newcastle
 Time and Date: 3:00 pm, Tue, 13^{th} Mar 2012
 Abstract:
Parabolic obstacle problems find applications in the financial markets for pricing American put options. We present a mixed and an equivalent variational inequality hpinterior penalty DG (IPDG) method combined with an hptime DG (TDG) method to solve parabolic obstacle problems approximatively. The contact conditions are resolved by a biorthogonal Lagrange multiplier and are componentwise decoupled. These decoupled contact conditions are equivlent to finding the root of a nonlinear complementary function. This nonlinear problem can in turn be solved efficiently by a semismooth Newton method. For the hpadaptivity a phierarchical error estimator in conjunction with a local analyticity estimate is employed. For the considered stationary problem, this leads to exponential convergence, and for the instationary problem to greatly improved convergence rates. Numerical experiments are given demonstrating the strengths and limitations of the approaches.
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 CARMA SEMINAR
 Speaker: Mr Neil Gillespie, School of Mathematics and Statistics, University of Western Australia
 Title: On connections between neighbour transitive codes and power line communication
 Location: Room V129, Mathematics Building (Callaghan Campus) The University of Newcastle
 Time and Date: 4:00 pm, Thu, 1^{st} Mar 2012
 Abstract:
Power line communication has been proposed as a possible solution to the "last mile" problem in telecommunications i.e. providing economical high speed telecommunications to millions of end users. As well as the usual background interference (noise), two other types of noise must also be considered for any successful practical implementation of power line communication. Coding schemes have traditionally been designed to deal only with background noise, and in such schemes it is often assumed that background noise affects symbols in codewords independently at random. Recently, however, new schemes have been proposed to deal with the extra considerations in power line communication. We introduce neighbour transitive codes as a group theoretic analogue to the assumption that background noise affects symbols independently at random. We also classify a family of neighbour transitive codes, and show that such codes have the necessary properties to be useful in power line communication.
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 CARMA SEMINAR
 Speaker: Wilson Ong, Department of Mathematics, Australian National University
 Title: A simplified proof of Hesselholts conjecture on Galois cohomology of Witt vectors of algebraic integers
 Location: Room V129, Mathematics Building (Callaghan Campus) The University of Newcastle
 Time and Date: 4:00 pm, Thu, 23^{rd} Feb 2012
 Abstract:
Let $K$ be a complete discrete valuation field of characteristic zero with residue field $k_K$ of characteristic $p > 0$. Let $L/K$ be a finite Galois extension with Galois group $G = \text{Gal}(L/K)$ and suppose that the induced extension of residue fields $k_L/k_K$ is separable. Let $W_n(.)$ denote the ring of $p$typical Witt vectors of length $n$. Hesselholt [Galois cohomology of Witt vectors of algebraic integers, Math. Proc. Cambridge Philos. Soc. 137(3) (2004), 551557] conjectured that the proabelian group ${H^1(G,W_n(O_L))}_{n>0}$ is isomorphic to zero. Hogadi and Pisolkar [On the cohomology of Witt vectors of $p$adic integers and a conjecture of Hesselholt, J. Number Theory 131(10) (2011), 17971807] have recently provided a proof of this conjecture. In this talk, we present a simplified version of the original proof which avoids many of the calculations present in that version.
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 CARMA OPTIMIZATION SEMINAR
 Speaker: Conjoint Prof Steve Wright, Computer Sciences Department and Wisconsin Institute for Discovery, University of WisconsinMadison
 Title: Packing Ellipsoids and Circles (with Application to Chromosome Arrangement)
 Location: Room V205, Mathematics Building (Callaghan Campus) The University of Newcastle
 Time and Date: 2:00 pm, Mon, 23^{rd} Jan 2012
 Abstract:
We consider the problem of packing ellipsoids of different size and shape in an ellipsoidal container so as to minimize a measure of total overlap. The motivating application is chromosome organization in the human cell nucleus. A bilevel optimization formulation is described, together with an algorithm for the general case and a simpler algorithm for the special case in which all ellipsoids are in fact spheres. We prove convergence to stationary points of this nonconvex problem, and describe computational experience. The talk describes joint work with Caroline Uhler (IST, Vienna).
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 CARMA SEMINAR
 Speaker: Nina Narodytska, unknown or leave blank,
 Title: Complexity of and Algorithms for Borda Manipulation
 Location: Room V129, Mathematics Building (Callaghan Campus) The University of Newcastle
 Time and Date: 3:00 pm, Tue, 10^{th} Jan 2012
 Abstract:
We prove the it is NPhard for a coalition of two
manipulators to compute how to manipulate the Borda voting rule.
This resolves one of the last open problems in the computational
complexity of manipulating common voting rules. Because
of this NPhardness, we treat computing a manipulation
as an approximation problem where we try to minimize
the number of manipulators. Based on ideas from bin packing
and multiprocessor scheduling, we propose two new approximation
methods to compute manipulations of the Borda
rule. Experiments show that these methods significantly outperform
the previous best known approximation method. We
are able to find optimal manipulations in almost all the randomly
generated elections tested. Our results suggest that,
whilst computing a manipulation of the Borda rule by a coalition
is NPhard, computational complexity may provide only
a weak barrier against manipulation in practice.
We also consider Nanson’s and Baldwin’s voting rules that
select a winner by successively eliminating candidates with low
Borda scores. We theoretically and experimentally
demonstrate that these rules are significantly
more difficult to manipulate compared to Borda rule.
In particular, with unweighted votes, it
is NPhard to manipulate either rule with one manipulator,
whilst with weighted votes, it is NPhard to manipulate either
rule with a small number of candidates and a coalition of manipulators.
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 CARMA SEMINAR
 Speaker: Dr Neil Saunders, The University of Sydney
 Title: Minimal Faithful Permutation Representations of Finite Groups
 Location: Room V129, Mathematics Building (Callaghan Campus) The University of Newcastle
 Time and Date: 4:00 pm, Thu, 15^{th} Dec 2011
 Abstract:
The minimal degree of a finite group $G$ is the smallest nonnegative integer $n$ such that $G$ embeds in $\Sym(n)$. This defines an invariant of the group $\mu(G)$. In this talk, I will present some interesting examples of calculating $\mu(G)$ and examine how this invariant behaves under taking direct products and homomorphic images.
In particular, I will focus on the problem of determining the smallest degree for which we obtain a strict inequality $\mu(G \times H) < \mu(G) + \mu(H)$, for two groups $G$ and $H$. The answer to this questions also leads us to consider the problem of exceptional permutation groups. These are groups $G$ that possess a normal subgroup $N$ such that $\mu(G/N) > \mu(G)$. They are somewhat mysterious in the sense that a particular homomorphic image becomes 'harder' to faithfully represent than the group itself. I will present some recent examples of exceptional groups and detail recent developments in the 'abelian quotients conjecture' which states that $\mu(G/N) < \mu(G)$, whenever $G/N$ is abelian.
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 CARMA SEMINAR
 Speaker: Prof John Giles, School of Mathematical and Physical Sciences, The University of Newcastle
 Title: Persistence properties for Banach spaces
 Location: Room V129, Mathematics Building (Callaghan Campus) The University of Newcastle
 Time and Date: 4:00 pm, Thu, 8^{th} Sep 2011
 Abstract:
We are interested in local geometrical properties of a Banach space which are preserved under natural embeddings in all even dual spaces. An example of this behaviour which we generalise is:
if the norm of the space $X$ is Fréchet differentiable at $x \in S(X)$ then the norm of the second dual $X^{**}$ is Fréchet differentiable at $\hat{x}\in S(X)$ and of $X^{****}$ at $\hat{\hat{x}} \in S(X^{****})$ and so on....
The results come from a study of Hausdorff upper semicontinuity properties of the duality mapping characterising general differentiability conditions satisfied by the norm.
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 SIGMAOPT/CARMA SEMINAR
 Speaker: Liangjin Yao, CARMA, The University of Newcastle
 Title: The sum of a maximally monotone linear relation and the subdifferential of a proper lower semicontinuous convex function is maximally monotone
 Location: Room V205, Mathematics Building (Callaghan Campus) The University of Newcastle
 Access Grid Venue: UNewcastle [ENQUIRIES]
 Time and Date: 4:00 pm, Thu, 11^{th} Aug 2011
 Abstract:
The most important open problem in Monotone Operator Theory concerns the maximal monotonicity of the sum of two maximally monotone operators provided that Rockafellar's constraint qualification holds. In this talk, we prove the maximal monotonicity of the sum of a maximally monotone linear relation and the subdifferential of a proper lower semicontinuous convex function satisfying Rockafellar's constraint qualification. Moreover, we show that this sum operator is of type (FPV).
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 CARMA SEMINAR
 Speaker: Dr Erick Li, The University of Sydney
 Title: On Designing Optimal Permission Sets for Project Selection
 Location: Room V129, Mathematics Building (Callaghan Campus) The University of Newcastle
 Time and Date: 1:30 pm, Wed, 10^{th} Aug 2011
 Abstract:
This paper considers designing permission sets to influence the project selection decision made by
a betterinformed agent. The project characteristics are twodimensional. The principal can verify the characteristics of the project selected by the agent. However, the principal cannot observe the number and characteristics of those projects that the agent could, but does not, propose. The payoffs to the agent and the principal are different. Using calculus of variations, we solve the optimal permission set, which can be characterized by a threshold function. We obtain comparative statics on the preference alignment and expected number of projects available. When outcomebased incentives are feasible, we discuss the use of financial inducement to maximize the social welfare. We also extend our analysis to two cases: 1) when one of the project characteristics is unobservable; and 2) when there are multiple agents with private preferences and the principal must establish a universal permission set.
Key words: calculus of variations, optimal permission set, project management.
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 CARMA SEMINAR
 Speaker: Wojciech Kozlowski, University of NSW
 Title: Common fixed points for semigroups of pointwise Lipschitzian mappings in Banach spaces
 Location: Room V129, Mathematics Building (Callaghan Campus) The University of Newcastle
 Time and Date: 2:00 pm, Fri, 22^{nd} Jul 2011
 Abstract:
We will investigate the existence of common fixed points for pointwise Lipschitzian semigroups of nonlinear mappings $Tt : C  C$ where $C$ is a bounded, closed, convex subset of a uniformly convex Banach space $X$, i.e. a family such that $T0(x) = x$, $Ts+t = Ts(Tt(x))$, where each $Tt$ is pointwise Lipschitzian, i.e. there exists a family of functions $at : C  [0;x)$ such that $Tt(x)Tt(y) < at(x)xy$ for $x$, $y \in C$. We will also demonstrate how the asymptotic aspect of the pointwise Lipschitzian semigroups can be expressed in terms of the respective Frechet derivatives. We will discuss some questions related to the weak and strong convergence of certain iterative algorithms for the construction of the stationary and periodic points for such semigroups.
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 CARMA SEMINAR
 Speaker: Dr Riki Brown, University College London and University of Newcastle Upon Tyne
 Title: Metric Projections in Spaces of Continuous Functions
 Location: Room V129, Mathematics Building (Callaghan Campus) The University of Newcastle
 Time and Date: 3:00 pm, Wed, 15^{th} Jun 2011
 Abstract:
Let $T$ be a topological space (a compact subspace of ${\mathbb R^m}$, say) and let $C(T)$ be the space of real continuous functions on $T$, equipped with the uniform norm: $f = \text{max}_{t\in T}f(t)$ for all $f \in C(T)$. Let $G$ be a finitedimensional linear subspace of $C(T)$. If $f \in C(T)$ then
$$d(f,G) = \text{inf}\{f−g : g \in G\}$$
is the distance of $f$ from $G$, and
$$P_G(f) = \{g \in G : f−g = d(f,G)\}$$
is the set of best approximations to $f$ from $G$. Then
$$P_G : C(T) \rightarrow P(G)$$
is the setvalued metric projection of $C(T)$ onto $G$. In the 1850s P. L. Chebyshev considered $T = [a, b]$ and $G$ the space of polynomials of degree $\leq n − 1$. Our concern is with possible properties of $P_G$. The historical development, beginning with Chebyshev, Haar (1918) and Mairhuber (1956), and the present state of knowledge will be outlined. New results will demonstrate that the story is still incomplete.
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 CARMA SEMINAR
 Speaker: Coenraad Labuschagne, University of South Australia
 Title: The ChaneyShaefer $\ell$Tensor Product $E\tilde{\otimes}_{\ell}Y$
 Location: Room V129, Mathematics Building (Callaghan Campus) The University of Newcastle
 Time and Date: 4:00 pm, Thu, 21^{st} Apr 2011
 Abstract:
The ChaneySchaefer $\ell$tensor product $E\tilde{\otimes}_{\ell}Y$ of a Banach lattice $E$ and a Banach space $Y$ may be viewed as an extension of the Bochner space $L^p(\mu,Y) (1\leq p < \infty)$. We consider an extension of a classical martingale characterization of the Radon Nikodým property in $L^p(\mu,Y)$, for $1 < p < 1$, to $E\tilde{\otimes}_{\ell}Y$. We consider consequences of this extension, and time permitting, use it to represent setvalued measures of risk dened on Banach latticevalued Orlicz hearts.
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 CARMA SEMINAR
 Speaker: Assoc Prof Murray Elder, CARMA, The University of Newcastle
 Title: Finding short words in the first Grigorchuk group
 Location: Room V129, Mathematics Building (Callaghan Campus) The University of Newcastle
 Time and Date: 4:00 pm, Thu, 24^{th} Mar 2011
 Abstract:
In the 80's R.Grigorchuk found a finitely generated group such that the number of elements that can be written as a product of at most \(n\) generators grows faster than any polynomial in \(n\), but slower than any exponential in \(n\), socalled "intermediate" growth.
It can be described as an group of automorphisms of an infinite rooted binary tree, or in terms of abstract computing devices called "noninitial finite transducers".
In this talk I will describe what some of these short words/products of generators look like, and speculate on the asymptotic growth rate of all short words of length \(n\).
This is joint unpublished work with Mauricio Gutierrez (Tufts) and Zoran Sunic (Texas A&M).
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 CARMA SEMINAR
 Speaker: Various Members, CARMA, The University of Newcastle
 Title: CARMA Show and Tell Part II
 Location: Room V205, Mathematics Building (Callaghan Campus) The University of Newcastle
 Time and Date: 1:30 pm, Mon, 7^{th} Feb 2011
 Abstract:
Various Vacation Scholars, HRD students and CARMA RAs will report on their work. This involves visualization and computation, practice and theory. Everyone is welcome to see what they have done and what they propose to do.
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 CARMA SEMINAR
 Speaker: Various Members, CARMA, The University of Newcastle
 Title: CARMA Show and Tell
 Location: Room V205, Mathematics Building (Callaghan Campus) The University of Newcastle
 Time and Date: 1:30 pm, Mon, 24^{th} Jan 2011
 Abstract:
Various Vacation Scholars, HRD students and CARMA RAs will report on their work. This involves visualization and computation, practice and theory. Everyone is welcome to see what they have done and what they propose to do.
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 CARMA SEMINAR
 Speaker: Prof ShingTung Yau, Department of Mathematics, Harvard University
 Title: The Shape of Inner Space: String theory and the geometry of the universe's hidden dimensions
 Location: Room V206, Mathematics Building (Callaghan Campus) The University of Newcastle
 Access Grid Venue: Monash University [ENQUIRIES]
 Time and Date: 11:00 am, Thu, 25^{th} Nov 2010
 Abstract:
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 CARMA SEMINAR
 Speaker: Prof Michael Barnsley, Mathematical Sciences Institute, Australian National University
 Title: Real Projective Iterated Function Systems
 Location: Room VG10, Mathematics Building (Callaghan Campus) The University of Newcastle
 Time and Date: 10:30 am, Fri, 11^{th} Jun 2010
 Abstract:
I will describe four recent theorems, developed jointly with Andrew Vince and David C. Wilson (both of the University of Florida) that reveal a surprisingly rich theory associated with an attractor of a projective iterated function system (IFS). The first theorem characterizes when a projective IFS has an attractor that avoids a hyperplane. The second theorem establishes that a projective IFS has at most one attractor. In the third theorem the classical duality between points and hyperplanes in projective space leads to connections between attractors that avoid hyperplanes and repellers that avoid points and an associated index, which is a nontrivial projective invariant, is defined. I will link these results to the Conley decomposition theorem.
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