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arXiv 1004.4980math.ACmath.CO
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图相关代数的Koszulness、克鲁尔维数及其它性质

Koszulness, Krull Dimension and Other Properties of Graph-Related Algebras

Alexandru Constantinescu, Matteo Varbaro

摘要:

图G的基本覆盖代数记为\A(G),它是由Juergen Herzog引入的,作为图G的顶点覆盖代数的一个合适的商.本文证明了:如果图是二部图,则\A(G)是具有拉直律的齐次代数,因而是Koszul.进一步,我们利用G的组合学计算了\A(G)的克鲁尔维数.作为结果,我们得到了纯余维为2的单项理想的算术秩的新的上界。最后,我们刻画了一类图的边理想的Cohen-Macaulay性质和Castelnuovo-Mumford正则性。

英文摘要:

The algebra of basic covers of a graph G, denoted by \A(G), was introduced by Juergen Herzog as a suitable quotient of the vertex cover algebra. In this paper we show that if the graph is bipartite then \A(G) is a homogeneous algebra with straightening laws and thus is Koszul. Furthermore, we compute the Krull dimension of \A(G) in terms of the combinatorics of G. As a consequence we get new upper bounds on the arithmetical rank of monomial ideals of pure codimension 2. Finally, we characterize the Cohen-Macaulay property and the Castelnuovo-Mumford regularity of the edge ideal of a certain class of graphs.

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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