Dr. John Lattanzio of the Mathematics Department presented “Partition Types” at the twenty-third Midwest Conference on Combinatorics, Cryptography, and Computing on October 4, 2009.

This year's conference was in honor of the sixty-eighth birthday of Walter Wallis and was held at the Rochester Institute of Technology.

For a graph *G* having chromatic number *k*, an equivalence relation is defined on the set *X* consisting of all proper vertex *k*-colorings of *G*. This leads naturally to an equivalence relation on the set *P* consisting of all partitions of *V* (*G*) into *k* independent subsets of color classes. The notion of a partition type arises and the algebra of types is investigated. Visual assistance is provided by **Mathematica**.