 
Summary: COLLOQUIUM
University of Regina
Department of Mathematics and Statistics
Speaker: Ryan Tifenbach (University of Regina)
Title: Eigenvalues of strongly selfdual graphs
Time & Place: Friday, November 7, 3:30  4:30 pm, CL 232
Abstract
Let G be a graph with adjacency matrix M. The dual of G, denoted G+
,
is another graph whose adjacency matrix M+
satisfies
M+
= SM1
S,
where S is a symmetric unitary matrix of a certain type. (Not every graph
possesses a dual.) The dual of a graph G is a type of graphinverse, as it is
associated with the inverse of the adjacency matrix of G. If the graph G has
welldefined G+
and we also have G+ = G, we refer to G as selfdual. In a
previous session, we examined the combinatorial structure of such a graph.
