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GORENSTEIN AND Sr PATH IDEALS OF CYCLES

Published online by Cambridge University Press:  26 August 2014

DARIUSH KIANI
Affiliation:
Department of Pure Mathematics, Faculty of Mathematics and Computer Science, Amirkabir University of Technology (Tehran Polytechnic), 424, Hafez Ave., Tehran 15914, Iran, and School of Mathematics, Institute for Research in Fundamental Sciences (IPM), Tehran, Iran e-mail: [email protected], [email protected]
SARA SAEEDI MADANI
Affiliation:
NAOKI TERAI
Affiliation:
Naoki Terai, Department of Mathematics, Faculty of Culture and Education, Saga University, Saga 840-8502, Japan e-mail: [email protected]
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Abstract

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Let R = k[x1,…,xn], where k is a field. The path ideal (of length t ≥ 2) of a directed graph G is the monomial ideal, denoted by It(G), whose generators correspond to the directed paths of length t in G. Let Cn be an n-cycle. We show that R/It(Cn) is Sr if and only if it is Cohen-Macaulay or $\lceil \frac{n}{n-t-1}\rceil\geq r+3$. In addition, we prove that R/It(Cn) is Gorenstein if and only if n = t or 2t + 1. Also, we determine all ordinary and symbolic powers of It(Cn) which are Cohen-Macaulay. Finally, we prove that It(Cn) has a linear resolution if and only if t ≥ n − 2.

Type
Research Article
Copyright
Copyright © Glasgow Mathematical Journal Trust 2014 

References

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