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Let $G$ be a simple graph and $I(G)$ be its edge ideal. In this article, we study the Castelnuovo-Mumford regularity of symbolic powers of edge ideals of join of graphs. As a consequence, we prove Minh's conjecture for wheel graphs,…

Commutative Algebra · Mathematics 2020-08-04 Arvind Kumar , Rajiv Kumar , Rajib Sarkar

In this paper we study irreducible representations and symbolic Rees algebras of monomial ideals. Then we examine edge ideals associated to vertex-weighted oriented graphs. These are digraphs having no oriented cycles of length two with…

Commutative Algebra · Mathematics 2018-10-23 Philippe Gimenez , Jose Martínez-Bernal , Aron Simis , Rafael H. Villarreal , Carlos E. Vivares

We graph-theoretically characterize triangle-free Gorenstein graphs $G$. As an application, we classify when $I(G)^2$ is Cohen-Macaulay.

Commutative Algebra · Mathematics 2015-09-01 Do Trong Hoang , Tran Nam Trung

The famous Gallai's Conjecture states that any connected graph with n vertices has a path decomposition containing at most (n+1)/2 paths. In this note, we explore graphs generated from removing edges from complete graphs. We first provide…

Combinatorics · Mathematics 2022-11-01 Hua Wang , Andrew Zhang

Let (P,<) be a finite poset and let G be its comparability graph. If cl(G) is the clutter of maximal cliques of G, we prove that cl(G) satisfies the max-flow min-cut property and that its edge ideal is normally torsion free. We prove that…

Commutative Algebra · Mathematics 2011-04-05 Luis A. Dupont , Rafael H Villarreal

We give a combinatorial characterisation of connected graphs whose binomial edge ideals are of K\"{o}nig type, developed independently to the similar characterisation given by LaClair in arXiv:2304.13299, and exhibit some classes of graphs…

Commutative Algebra · Mathematics 2024-12-16 David Williams

In this article, we obtain an upper bound for the regularity of the binomial edge ideal of a graph whose every block is either a cycle or a clique. As a consequence, we obtain an upper bound for the regularity of binomial edge ideal of a…

Commutative Algebra · Mathematics 2020-10-23 A. V. Jayanthan , Rajib Sarkar

Berge Conjecture states that every bridgeless cubic graph has 5 perfect matchings such that each edge is contained in at least one of them. In this paper, we show that Berge Conjecture holds for two classes of cubic graphs, cubic graphs…

Combinatorics · Mathematics 2016-03-01 Wuyang Sun

In attempting to understand how combinatorial modifications alter algebraic properties of monomial ideals, several authors have investigated the process of adding "whiskers" to graphs. In this paper, we study a similar construction to build…

Commutative Algebra · Mathematics 2019-11-05 Jennifer Biermann , Christopher A. Francisco , Huy Tài Hà , Adam Van Tuyl

Let $G$ be the circulant graph $C_n(S)$ with $S \subseteq \{1, 2, \dots, \lfloor \frac{n}{2} \rfloor\}$, and let $I(G)$ denote the edge ideal in the polynomial ring $R=\mathbb{K}[x_0, x_1, \dots, x_{n-1}]$ over a field $\mathbb{K}$. In this…

Combinatorics · Mathematics 2025-10-06 Sonica Anand , Amit Roy

In this paper, we explain the regularity, projective dimension and depth of edge ideal of some classes of graphs in terms of invariants of graphs. We show that for a $C_5$-free vertex decomposable graph $G$, $\T{reg}(R/I(G))= c_G$, where…

Commutative Algebra · Mathematics 2017-01-24 Fahimeh Khosh-Ahang , Somayeh Moradi

Let $G$ be a permutation graph. We show that $G$ is Cohen-Macaulay if and only if $G$ is unmixed and vertex decomposable. When this is the case, we obtain a combinatorial description for the $a$-invariant of $G$. Moreover, we characterize…

Commutative Algebra · Mathematics 2025-02-28 Antonino Ficarra , Somayeh Moradi

We use the correspondence between hypergraphs and their associated edge ideals to study the minimal graded free resolution of squarefree monomial ideals. The theme of this paper is to understand how the combinatorial structure of a…

Commutative Algebra · Mathematics 2007-06-13 Huy Tai Ha , Adam Van Tuyl

As the binomial edge ideal of a graph is always generated by homogeneous quadratic polynomials corresponding to the edges of the graph, the question of when a binomial edge ideal defines a Koszul algebra has been studied by many authors…

Commutative Algebra · Mathematics 2026-01-22 Adam LaClair , Matthew Mastroeni , Jason McCullough , Irena Peeva

In this article, we characterize Cohen-Macaulay permutation graphs. In particular, we show that a permutation graph is Cohen-Macaulay if and only if it is well-covered and there exists a unique way of partitioning its vertex set into $r$…

Commutative Algebra · Mathematics 2024-11-07 P. V. Cheri , Deblina Dey , Akhil K , Nirmal Kotal , Dharm Veer

In this paper, we give a new criterion for the Cohen-Macaulayness of vertex splittable ideals, a family of monomial ideals recently introduced by Moradi and Khosh-Ahang. Our result relies on a Betti splitting of the ideal and provides an…

Commutative Algebra · Mathematics 2024-03-22 Marilena Crupi , Antonino Ficarra

In this paper, we introduce and study families of squarefree monomial ideals called clique ideals and independence ideals that can be associated to a finite graph. A family of clique ideals with linear resolutions has been characterized.…

Commutative Algebra · Mathematics 2017-12-05 Somayeh Moradi

The goal of this paper is to explicitly detect all the arithmetic genera of arithmetically Cohen-Macaulay projective curves with a given degree $d$. It is well-known that the arithmetic genus $g$ of a curve $C$ can be easily deduced from…

Commutative Algebra · Mathematics 2015-03-16 Francesca Cioffi , Paolo Lella , Maria Grazia Marinari

Inspired by several recent papers on the edge ideal of a graph G, we study the equivalent notion of the independence complex of G. Using the tool of vertex decomposability from geometric combinatorics, we show that 5-chordal graphs with no…

Combinatorics · Mathematics 2011-12-30 Russ Woodroofe

In this paper, we give a lengthy proof of a small result! A graph is bisplit if its vertex set can be partitioned into three stable sets with two of them inducing a complete bipartite graph. We prove that these graphs satisfy the…

Discrete Mathematics · Computer Science 2023-06-22 Laurent Beaudou , Giacomo Kahn , Matthieu Rosenfeld