Daryl
DeFord
Department of
Mathematics and Statistics
Washington State University
Title: The Discharging Method for Graph Colorings
Abstract: The discharging method is a combinatorial
proof technique that uses properties of graph
embeddings together with Euler's theorem to derive
existence results. This month, the method turns 117
years old, and while it is best known for providing a
crucial step in the proof of the four-color theorem,
recent generalizations of this method have been used
to prove results about graph colorings and higher
dimensional embeddings. In this talk I will discuss
the history of this method and demonstrate several
examples of its use in graph-theoretic proofs.