English

Gin and Lex of certain monomial ideals

Commutative Algebra 2007-05-23 v2

Abstract

Let A=K[x1,...,xn]A = K[x_1, ..., x_n] denote the polynomial ring in nn variables over a field KK of characteristic 0 with each degxi=1\deg x_i = 1. Given arbitrary integers ii and jj with 2in2 \leq i \leq n and 3jn3 \leq j \leq n, we will construct a monomial ideal IAI \subset A such that (i) βk(I)<βk(\Gin(I))\beta_k(I) < \beta_k(\Gin(I)) for all k<ik < i, (ii) βi(I)=βi(\Gin(I))\beta_i(I) = \beta_i(\Gin(I)), (iii) β(\Gin(I))<β(\Lex(I))\beta_\ell(\Gin(I)) < \beta_\ell(\Lex(I)) for all <j\ell < j and (iv) βj(\Gin(I))=βj(\Lex(I))\beta_j(\Gin(I)) = \beta_j(\Lex(I)), where \Gin(I)\Gin(I) is the generic initial ideal of II with respect to the reverse lexicographic order induced by x1>>...>xnx_1 > >... > x_n and where \Lex(I)\Lex(I) is the lexsegment ideal with the same Hilbert function as II.

Keywords

Cite

@article{arxiv.math/0509403,
  title  = {Gin and Lex of certain monomial ideals},
  author = {Satoshi Murai and Takayuki Hibi},
  journal= {arXiv preprint arXiv:math/0509403},
  year   = {2007}
}

Comments

9 pages, minor grammatical changes

R2 v1 2026-07-22T17:24:39.481Z