English

Affine semigroups of maximal projective dimension-II

Commutative Algebra 2023-07-20 v2

Abstract

If the Krull dimension of the semigroup ring is greater than one, then affine semigroups of maximal projective dimension (MPD\mathrm{MPD}) are not Cohen-Macaulay, but they may be Buchsbaum. We give a necessary and sufficient condition for simplicial MPD\mathrm{MPD}-semigroups to be Buchsbaum in terms of pseudo-Frobenius elements. We give certain characterizations of \prec-almost symmetric C\mathcal{C}-semigroups. When the cone is full, we prove the irreducible C\mathcal{C}-semigroups, and \prec-almost symmetric C\mathcal{C}-semigroups with Betti-type three satisfy the extended Wilf's conjecture. For e4e \geq 4, we give a class of MPD-semigroups in N2\mathbb{N}^2 such that there is no upper bound on the Betti-type in terms of embedding dimension ee. Thus, the Betti-type may not be a bounded function of the embedding dimension. We further explore the submonoids of Nd\mathbb{N}^d, which satisfy the Arf property.

Keywords

Cite

@article{arxiv.2304.14806,
  title  = {Affine semigroups of maximal projective dimension-II},
  author = {Om Prakash Bhardwaj and Indranath Sengupta},
  journal= {arXiv preprint arXiv:2304.14806},
  year   = {2023}
}