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arXiv 1301.4249math.ACmath.AGmath.CO
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某些格理想的正则性和代数性质

Regularity and algebraic properties of certain lattice ideals

Jorge Neves, Maria Vaz Pinto, Rafael H. Villarreal

摘要:

研究了某些格理想的正则性和代数性质。建立了域K上N-分次多项式环的分次格理想族与具有标准分次的多项式环的分次格理想族之间的映射I --> I.证明了该映射保持I的完全交性和正则性,但不保持I的度。我们将希尔伯特级数与I和I ~的生成元联系起来。如果dim(I)=1,我们将I和I ~的次数联系起来。证明了某些格理想的正则性在一定意义下是可加的。然后,我们给出一些应用。对于有限域,我们用半群的Frobenius数给出了退化环面的消失理想的正则性公式。构造了有限域上具有一定正则性和度的消失理想。设X是域K上射影空间的子集。证明了X的消失理想是1维格理想当且仅当X是射影环面的有限子群。对于有限域,证明了X是射影环面的子群当且仅当X由单项式参数化。本文用图的块的消失理想的正则性来表示二部图的消失理想的正则性。

英文摘要:

We study the regularity and the algebraic properties of certain lattice ideals. We establish a map I --> I\~ between the family of graded lattice ideals in an N-graded polynomial ring over a field K and the family of graded lattice ideals in a polynomial ring with the standard grading. This map is shown to preserve the complete intersection property and the regularity of I but not the degree. We relate the Hilbert series and the generators of I and I\~. If dim(I)=1, we relate the degrees of I and I\~. It is shown that the regularity of certain lattice ideals is additive in a certain sense. Then, we give some applications. For finite fields, we give a formula for the regularity of the vanishing ideal of a degenerate torus in terms of the Frobenius number of a semigroup. We construct vanishing ideals, over finite fields, with prescribed regularity and degree of a certain type. Let X be a subset of a projective space over a field K. It is shown that the vanishing ideal of X is a lattice ideal of dimension 1 if and only if X is a finite subgroup of a projective torus. For finite fields, it is shown that X is a subgroup of a projective torus if and only if X is parameterized by monomials. We express the regularity of the vanishing ideal over a bipartie graph in terms of the regularities of the vanishing ideals of the blocks of the graph.

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

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