Abstract:
A proper coloring of a graph is a way to label the vertices such
that adjacent vertices get different labels. (The famous Four Color
Theorem, proven in 1976, says that any graph that can be drawn on a
blackboard without edge crossings admits at least one proper coloring with
at most four different colors.) I'll discuss the beautiful theorem of
Möbius inversion for functions on posets, and explain what it has to do with
coloring graphs.
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