• CARMA OPTIMIZATION SEMINAR
  • Speaker: Conjoint Prof Steve Wright, Computer Sciences Department and Wisconsin Institute for Discovery, University of Wisconsin-Madison
  • 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, 23rd 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 COLLOQUIUM AND SIGMAOPT SEMINAR
  • Speaker: Conjoint Prof Steve Wright, Computer Sciences Department and Wisconsin Institute for Discovery, University of Wisconsin-Madison
  • Title: More Tools and Applications of Sparse Optimization
  • Location: Room V206, Mathematics Building (Callaghan Campus) The University of Newcastle
  • Access Grid Venue: UNewcastle [ENQUIRIES]
  • Time and Date: 4:00 pm, Thu, 24th Jun 2010
  • Abstract:

    Machine learning problems are a particularly rich source of applications for sparse optimization, giving rise to a number of formulations that require specialized solvers and structured, approximate solutions. As case studies, we discuss two such applications - sparse SVM classification and sparse logistic regression - and present algorithms that are assembled from different components, including stochastic gradient methods, random approximate matrix factorizations, block coordinate descent, and projected Newton methods. We also describe a third (distantly related) application to selection of captive breeding populations for endangered species using binary quadratic programming, a project started during a visit to Newcastle in June 2009.

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