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Sequentially Cohen-Macaulay Edge Ideals

Christopher A. Francisco·Adam Van Tuyl
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Abstract

Let G be a simple undirected graph on n vertices, and let I(G) \subseteq R = k[x_1,...,x_n] denote its associated edge ideal. We show that all chordal graphs G are sequentially Cohen-Macaulay; our proof depends upon showing that the Alexander dual of I(G) is componentwise linear. Our result complements Faridi's theorem that the facet ideal of a simplicial tree is sequentially Cohen-Macaulay and implies Herzog, Hibi, and Zheng's theorem that a chordal graph is Cohen-Macaulay if and only if its edge ideal is unmixed. We also characterize the sequentially Cohen-Macaulay cycles and produce some examples of nonchordal sequentially Cohen-Macaulay graphs.

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Christopher A. Francisco, Adam Van Tuyl. 2006-04-12. Sequentially Cohen-Macaulay Edge Ideals. https://arxiv.org/abs/math/0511022

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