English

Unmixed and Cohen--Macaulay weighted oriented K\"onig graphs

Commutative Algebra 2019-10-01 v1 Combinatorics

Abstract

Let DD be a weighted oriented graph, whose underlying graph is GG, and let I(D)I(D) be its edge ideal. If GG has no 33-, 55-, or 77-cycles, or GG is K\"{o}nig, we characterize when I(D)I(D) is unmixed. If GG has no 33- or 55-cycles, or GG is K\"onig, we characterize when I(D)I(D) is Cohen--Macaulay. We prove that I(D)I(D) is unmixed if and only if I(D)I(D) is Cohen--Macaulay when GG has girth greater than 77 or GG is K\"onig and has no 44-cycles.

Keywords

Cite

@article{arxiv.1909.13295,
  title  = {Unmixed and Cohen--Macaulay weighted oriented K\"onig graphs},
  author = {Yuriko Pitones and Enrique Reyes and Rafael H. Villarreal},
  journal= {arXiv preprint arXiv:1909.13295},
  year   = {2019}
}
R2 v1 2026-06-23T11:29:26.809Z