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math.CO1999
Sinks in Acyclic Orientations of Graphs
David D. Gebhard, Bruce E. Sagan
Greene and Zaslavsky proved that the number of acyclic orientations of a graph with a unique sink is, up to sign, the linear coefficient of the chromatic polynomial. We give three…
math.CO1999
A Noncommutative Chromatic Symmetric Function
David D. Gebhard, Bruce E. Sagan
Stanley associated with a graph G a symmetric function X_G which reduces to G's chromatic polynomial under a certain specialization of variables. He then proved various theorems ge…