Switching m-edge coloured graphs Speaker: Gary MacGillivray, University of Victoria Abstract: An m-edge-coloured graph consists of a set of vertices, any two of which are either joined by an edge of one of m colours or not joined at all. The operation of switching at a vertex v of an m-edge-coloured graph with respect to an element of a subgroup \Gamma of S_m  permutes the colours of the edges incident with v.  Switching defines an equivalence relation on the set…

Kemeny's constant for Markov chains and random walks on graphs Speaker: Jane Breen, Ontario Tech University Kemeny's constant is an interesting and useful quantifier of how well-connected the states of a Markov chain are. Though it was first introduced in the 1960s, interest in this concept has recently exploded. This talk will provide an introduction to Markov chains, an overview of the history of Kemeny’s constant, discussion of some applications, and a survey of recent results, with an emphasis on…

Time: 3:30 pm, Atlantic time, (4:00 pm NST) Wednesday, Feb. 12 Speaker: Robert Bailey, Memorial University Title: Computer constructions of distance-regular graphs with primitive automorphism groups Abstract: A graph is distance-regular if, for each vertex $v$ and each vertex $w$ at distance $i$ from $v$, the number of neighbours of $w$ at distances $i-1$, $i$ or $i+1$ from $v$ depends only on $i$, and not on the choice of $v$ or $w$.  These are highly-structured graphs with interesting structural and…

Speaker: Karen Meagher, University of Regina Title: Derangement graphs and the intersection density of permutation groups Abstract: Two permutations are intersecting if they both map some $i$ to the same point, equivalently, permutations $\sigma$ and $\pi$ are intersecting if and only if $\pi^{-1}\sigma$ has a fixed point. A set of permutations is called intersecting if any two permutations in the set are intersecting. For any transitive group the stabilizer of a point is an intersecting set. The intersection density of a permutation…