English

Alexander duality for the alternative polarizations of strongly stable ideals

Commutative Algebra 2019-09-23 v4

Abstract

We will define the Alexander duality for strongly stable ideals. More precisely, for a strongly stable ideal Ik[x1,,xn]I \subset \Bbbk[x_1, \ldots, x_n] with deg(m)d{\rm deg}(\mathsf{m}) \le d for all mG(I)\mathsf{m} \in G(I), its dual Ik[y1,,yd]I^* \subset \Bbbk[y_1, \ldots, y_d] is a strongly stable ideal with deg(m)n{\rm deg}(\mathsf{m}) \le n for all mG(I)\mathsf{m} \in G(I^*). This duality has been constructed by Fl\o\oystad et al. in a different manner, so we emphasis applications here. For example, we will describe the Hilbert serieses of the local cohomologies Hmi(S/I)H_\mathfrak{m}^i(S/I) using the irreducible decomposition of II (through the Betti numbers of II^*).

Keywords

Cite

@article{arxiv.1812.00571,
  title  = {Alexander duality for the alternative polarizations of strongly stable ideals},
  author = {Kosuke Shibata and Kohji Yanagawa},
  journal= {arXiv preprint arXiv:1812.00571},
  year   = {2019}
}

Comments

21 pages. We clarified the proofs especially in Section 3 and added Section 6