Bojan Mohar

It is an interesting (and not entirely obvious) fact that every graph admits an orientation of its edges so that the outdegrees at vertices form a "coloring" (outdegrees of any two adjacent vertices are different). The proper chromatic number $\Vec{...

The speaker will discuss the Four-Color Theorem and some of the outstanding problems left open after the proof.

Abstract: In 1992, Thomassen obtained a beautiful proof showing that every planar graphis 5-list-colorable. Some extensions of this result will be presented. Inparticular, a new proof of Thomassen's theorem will be outlined. This proof is...