Non-level semi-standard graded Cohen-Macaulay domain with $h$-vector $(h_0,h_1,h_2)$
Commutative Algebra
2016-10-12 v1 Combinatorics
Abstract
Let be an algebraically closed field of characteristic 0, and a Cohen-Macaulay graded domain with . If is semi-standard graded (i.e., is finitely generated as a -module), it has the -vector , which encodes the Hilbert function of . From now on, assume that . It is known that if is standard graded (i.e., ), then is level. We will show that, in the semi-standard case, if is not level, then divides . Conversely, for any positive integers and , there is a non-level with the -vector . Moreover, such examples can be constructed as Ehrhart rings (equivalently, normal toric rings).
Keywords
Cite
@article{arxiv.1610.03157,
title = {Non-level semi-standard graded Cohen-Macaulay domain with $h$-vector $(h_0,h_1,h_2)$},
author = {Akihiro Higashitani and Kohji Yanagawa},
journal= {arXiv preprint arXiv:1610.03157},
year = {2016}
}
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12 pages