PHD CONFIRMATION SEMINAR Speaker: Andrew Goh, The University of Newcastle Title: Pattern avoiding permutations Location: Room V206, Mathematics Building (Callaghan Campus) The University of Newcastle Time and Date: 10:00 am, Wed, 7th Jun 2017 Abstract: The research interest in pattern avoiding permutations is inspired by Donald Knuth’s work in stack-sorting. According to Knuth, a permutation can be sorted by passing through a single infinite stack if and only if it avoids a sub-permutation pattern 231. Murphy extended Knuth’s research by using two infinite stacks in series and found out that the basis for generated permutations is infinite but Elder proved that the basis is finite when one of the stack is limited to depth two and the permutations are algebraic. My research is to investigate the permutations generated by a stack of depth 3 and an infinite stack in series. It is to determine the basis and nature of the permutations in term of formal language. [Permanent link] 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, 30th Nov 2016 - Wed, 30th 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. [Permanent link]