We generalize the definition of the $cd$-index of a Eulerian poset to the class of semi-Eulerian posets. For connected simplicial semi-Eulerian Buchsbaum posets, we show that all coefficients of the $cd$-index are nonnegative. This proves a conjecture of Novik for odd-dimensional manifolds and extends it to the even-dimensional case. Joint work with Martina Juhnke and Lorenzo Venturello.
Back to Computational Interactions between Algebra, Combinatorics, and Discrete Geometry
Copyright. All Rights Reserved.