Abstract. We show that for proving the Stanley conjecture, it is sufficient to consider a very special class of monomial ideals. These ideals (or rather their lcm lattices) are in bijection with the simplicial spanning trees of skeletons of a simplex.We apply this result to verify the Stanley conjecture for quotients of monomial ideals with up to six generators. For seven generators we obtain a partial result.
IntroductionLet K be a field, S an N n -graded K-algebra and M a finitely generated Z n -graded S-module. The Stanley depth of M, denoted sdepth M, is a combinatorial invariant of M related to a conjecture of Stanley from 1982 [Sta82, Conjecture 5.1] (nowadays called the Stanley conjecture), which states that depth M ≤ sdepth M. We refer the reader to [Pou+09] for an introduction to the subject and to the survey by Herzog [Her13] for a comprehensive account of the known results. Most of the research concentrates on the particular case where S is a polynomial ring and M is either a monomial ideal I ⊂ S or a quotient S/I. In the present paper we will also work in this setting.The main result of the present paper is that for proving the Stanley conjecture for M = S/I or M = I, it is sufficient to consider certain very special ideals. These ideals (more precisely their lcm lattices) are in bijection with certain simplicial complexes which we call stoss complexes (short for Spanning Tree Of a Skeleton of a Simplex ):These complexes can be seen as high dimensional analogues of trees. They have already been studied by Kalai [Kal83] in 1983, and more recently by Duval, Klivans and Martin [DKM09] and others. For k ∈ N we denote by B(k) the boolean algebra on k generators, i.e. the set of all subsets of