
Displaying from Friday, May 31, 2013

May 2013

Friday 31 
15:00  SEMINAR  Groups and Combinatorics Seminar, (k,L)complexes and graph symmetry

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Abstract:
Given an integer k and a graph L, a (k,L)complex is a polygonal complex consisting of vertices, edges and faces such that each face is a regular kgon and the graph induced by the edges and faces at each vertex is isomorphic to L. Many questions about the existence and (...)


June 2013

Friday 07 
15:00  SEMINAR  Groups and Combinatorics Seminar, The Merino Welsh Conjecture

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Abstract:
Merino and Welsh conjectured that for any loopless bridgeless graph, the number of spanning trees is dominated either by the number of acyclic orientations of the graph, or by the number of totally cyclic orientations of the graph.
In this talk, I will discuss this (...)

Friday 14 
15:00  SEMINAR  Groups and Combinatorics Seminar, Recognising the Symmetric and Alternating Squares

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Abstract:
The fundamental goal of Computational Group Theory is recognition: given a group somehow represented in a computer (usually by generators), determine any information about the group that you can, as quickly as possible. This is `easy' if we have enough time and memory to write (...)

Friday 21 
This week the seminar will consist of three 20 minute talks, starting at 3pm Friday 21st of June in Blakers Lecture Theatre.
Talk 1
Mark Ioppolo
will speak on
Symmetry in coding theory: Constructing error control codes with group theory
Abst (...)


July 2013

Friday 05 
15:00  SEMINAR  Groups and Combinatorics Seminar, On PseudoInjective Group Algebra

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Abstract:
A module M is called pseudoinjective if for every submodule X of M, any monomorphism f : X > M can be extended to a homomorphism g : M > M. Let K be a field and G a group. It is well known that a group algebra K[G] is selfinjective if and only if the group (...)


August 2013

Friday 02 
15:00  SEMINAR  Groups and Combinatorics Seminar, Maximal arcs that contain regular hyperovals

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Abstract:
A maximal narc is a set of q(n1) + n points in a projective plane such that any line of the plane meets 0 or n of them. The most common maximal arcs, called the Mathon arcs, are constructed by taking the union of regular hyperovals. In particular, there are no known maximal 4 (...)

Friday 09 
15:00  SEMINAR  Groups and Combinatorics Seminar, Semisymmetric graphs of prime valency

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Abstract:
A graph is called Xsemisymmetric if the group X acts transitively on edges, but not on vertices. Such graphs are necessarily bipartite and biregular, of valencies k and l say. There is a natural relationship between semisymmetric graphs and amalgams of groups. This leads us (...)

Sunday 11 
10:00  OPEN DAY  2013 Open Day : Join us for our Centenary Open Day and experience all that UWA has to offer

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Come and find out about our undergraduate and postgraduate courses, career options, scholarship opportunities, our valuable research, community programs and facilities.
There's also residential college tours, handson activities, live music, entertainment, and plenty of fun activities (...)

Friday 16 
15:00  SEMINAR  Groups and Combinatorics Seminar, Decomposing tensor products over fields of small characteristic

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Abstract:
One motivation for this talk comes from representation theory: decomposing a tensor product of irreducible (or indecomposable) representations as a sum of smaller degree irreducible (or indecomposable) representations. Other motivations come from quantum mechanics and (...)

Friday 23 
15:00  SEMINAR  Groups and Combinatorics Seminar, Breaking symmetries of infinite graphs

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Abstract:
Symmetry breaking involves colouring the elements of a combinatorial structure so that the resulting structure has no nontrivial symmetries. In this talk I'll give an introduction to symmetry breaking, with a particular focus on infinite graphs. I'll also discuss a number of (...)

Friday 30 
15:00  SEMINAR  Groups and Combinatorics Seminar, The structure of 3separations of matroids

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Abstract:
In this talk, I will give an introduction to decomposition theory of 3connected matroids. In order to make it more accessible I will also introduce some related definitions and examples.


September 2013

Friday 06 
15:00  SEMINAR  Groups and Combinatorics Seminar, Connections between Graph Theory & Combinatorics on Words

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Abstract:
A string or word is usually thought of as a sequence of letters drawn from some alphabet. Applications to bioinformatics and other areas suggest the utility of defining strings on subsets of the alphabet instead  socalled "indeterminate" strings. I describe (...)

Friday 13 
15:00  SEMINAR  Groups and Combinatorics Seminar, On The Noncommuting Graph

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Abstract:
In this talk, we will consider the noncommuting graph of a nonabelian finite group G; its vertex set is the set of noncentral elements of G, and two distinct vertices x and y are joined by an edge if they do not commute together. Actually, we study some properties of the (...)

Friday 20 
15:00  SEMINAR  Groups and Combinatorics Seminar, Generalised quadrangles constructed from groups

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Abstract:
This is just a survey talk of various ways to construct all of the known finite generalised quadrangles starting with a group and a configuration of subgroups of that group. In particular, the speaker will give a summary of where one of the "retreat" problems is at.

Wednesday 25 
11:00  SEMINAR  Mathematics Colloquium: The CohenLenstra heuristics: from arithmetic to topology and back again

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Akshay Venkatesh (Stanford) Mahler Lecturer and IAS ProfessoratLarge
will speak on
The CohenLenstra heuristics: from arithmetic to topology and back again.
at 11am in the Science Library Access Grid room.
I will discuss some models of (...)

Friday 27 
15:00  SEMINAR  Groups and Combinatorics Seminar, Straightline programs with memory and applications to computational group theory

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Abstract:
Straightline programs offer a method for encoding group computations in a "black box" sense, namely without using specifics of the group's representation or how the group operations are performed. We advocate that straightline programs designed for group (...)


October 2013

Friday 11 
15:00  SEMINAR  Groups and Combinatorics Seminar, Multiply tiling Euclidean space by translating a convex object

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Abstract:
We study the problem of covering Euclidean space R^d by possibly overlapping translates of a convex body P, such that almost every point is covered exactly k times, for a fixed integer k. Such a covering of Euclidean space by translations is called a ktiling. We will first (...)

Friday 18 
15:00  SEMINAR  Groups and Combinatorics Seminar, Regular orbits of Sym(n) and Alt(n) on irreducible representations

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Abstract:
Given a finite group G and a faithful irreducible FGmodule V where F is a field of prime order, we can ask whether G has a regular orbit on the vectors of V. This problem is related to determining which primitive permutation groups of affine type have a base of size 2, as well (...)

Friday 25 
15:00  SEMINAR  Groups and Combinatorics Seminar, Coprime actions of finite linear groups

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Abstract:
Let H be a finite linear group acting completely reducibly on a finite vector space V. Gabriel Navarro asked: if the Horbits containing vectors a and b have coprime lengths m and n, is there an Horbit of length mn?
We answered, by showing that the Horbit containing a + b (...)


November 2013

Friday 01 
15:00  SEMINAR  Groups and Combinatorics Seminar, Algebraic geometry codes

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Abstract:
Codes arising from algebraic geometry, first introduced by Goppa, gained attention when Tsfasman–Vladut–Zink used them to improve the GilbertVarshamow bound. We will give a gentle introduction to some of the beautiful ideas from algebraic geometry used to build these codes (...)


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