# Coast to Coast Seminar Series: "Five-Colour Theorem and Beyond"

11:30 - 12:30

Rm10900

*Dr. Bojan Mohar*

Canada Research Chair in Graph Theory, Department of Mathematics, Simon Fraser University

### Abstract

In 1994, Carsten Thomassen published a beautiful simple proof confirming that every planar graph is 5-list-colourable. Another beautiful proof on a similar topic was given a few years later by Mike Albertson who proved that every precolouring of a set of vertices in a planar graph that are far apart from each other can be extended to a 5-colouring of the whole graph. After presenting these enlightening contributions, the speaker will discuss possible common generalizations of these results and report on some recent progress.