The h-vector of a matroid complex, paving matroids and the chip firing game
A non-empty set of monomials Σ is a multicomplex if for any monomial z in Σ and a monomial z′ such that z′|z, we have that z′ also belongs to Σ. A multicomplex Σ is called pure if all its maximal elements have the same degree. This notion is a generalization of the simplicial complex, and several invariants extend directly, as the f-vector of a multicomplex, which is the vector that lists the monomials grouped by degrees. A non-empty set of monomials Σ is a multicomplex if for any monomial z in Σ and a monomial z′ such that z′|z, we have that z′ also belongs to Σ. A multicomplex Σ is called pure if all its maximal elements have the same degree. This notion is a generalization of the simplicial complex, and several invariants extend directly, as the f-vector of a multicomplex, which is the vector that lists the monomials grouped by degrees. The relevance of multicomplexes in matroid theory is partly due to a 1977 Richard Stanley conjecture that says that the h-vector of a matroid complex is the f-vector of a pure multicomplex. This has been proved for several families of matroids. In this talk, we review some results of Stanley’s conjecture, mainly for paving and cographic matroids. A paving matroid is one in which all its circuits have a size of at least the rank of the matroid. While, the chip firing game is a solitaire game played on a connected graph G that surprisingly is related to the h-vector of the bond matroid of G.