Title: Constructing cospectral graphs with a different switchingSpeaker: Chris Godsil Affiliation: University of Waterloo Room: MC 6486
Many years ago, Brendan McKay and I introduced a construction of pairs of cospectral graphs, sometimes known as local switching. In the same paper we introduced a second switching technique which produces, as special cases, the smallest pair of cospectral graphs and the smallest pair of connected cospectral graphs.
Title: Convex drawings of complete graphs: topology meets geometrySpeaker: Bruce Richter Affiliation: University of Waterloo Room: MC 5479
A drawing D of the complete graph K(n) is the sphere is characterized by, for each isomorph J of K(5), D[J] is homeomorphic to one of the three rectilinear drawings of K(5). Every drawing of K(n) in the plane with all edges straight-line segments is obviously convex. Thus, convex drawings generalize planar point sets that are in general position.