Combinatorics and Graph Theory

Josh Hallam from Loyola Marymount University will be speaking.

The presentation is titled "Whitney Duals of Graded Posets."

This event takes place online via Zoom.

The event description is as follows:

To each graded poset one can associate two sequences of numbers; the Whitney numbers of the first kind and the Whitney numbers of the second kind. One sequence keeps track of the Möbius function at each rank level and the other keeps track of the number of elements at each rank level. The Whitney numbers appear in many contexts in combinatorics. For example, they appear as the coefficients of the chromatic polynomial of a graph and can be used to compute the number of regions in a real hyperplane arrangement. We say that posets P and Q are Whitney duals if the Whitney numbers of the first kind of P are the Whitney numbers of the second kind of Q and vice-versa. In this talk, we will discuss a method to construct Whitney duals using edge labelings and quotient posets. We will also discuss some applications of Whitney duals. This is joint work with Rafael S. González D'León.

Location:	Zoom link provided on Math Seminars page [map]
Price:	free
Sponsor:	Department of Mathematics
Contact:	Department of Mathematics (517) 353-0844
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