The projective dimension of sequentially Cohen-Macaulay monomial ideals
arXiv:1310.5598
Abstract
In this short note we prove that the projective dimension of a sequentially Cohen-Macaulay square-free monomial ideal is equal to the maximal height of its minimal primes (also known as the big height), or equivalently, the maximal cardinality of a minimal vertex cover of its facet complex. This in particular gives a formula for the projective dimension of facet ideals of these classes of ideals, which are known to be sequentially Cohen-Macaulay: graph trees and simplicial trees, chordal graphs and some cycles, chordal clutters and graphs, and some path ideals to mention a few. Since polarization preserves projective dimension, our result also gives the projective dimension of any sequentially Cohen-Macaulay monomial ideal.
Since posting this paper we have found that the same result regarding projective dimension of square-free monomial ideals appears in the paper of Morey and Villarreal