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For the edge ideal $I(\D)$ of a weighted oriented graph $\D$, we prove that its symbolic powers $I(\D)^{(t)}$ are Cohen-Macaulay for all $t\geqslant 1$ if and only if the underlying graph $G$ is composed of a disjoint union of some complete…

Commutative Algebra · Mathematics 2025-09-11 Truong Thi Hien , Jiaxin Li , Tran Nam Trung , Guangjun Zhu

Squarefree powers of edge ideals are intimately related to matchings of the underlying graph. In this paper we give bounds for the regularity of squarefree powers of edge ideals, and we consider the question of when such powers are linearly…

Commutative Algebra · Mathematics 2019-09-26 Nursel Erey , Jürgen Herzog , Takayuki Hibi , Sara Saeedi Madani

The vertex cover ideal $J(G)$ of a finite graph $G$ is studied. We characterize when a Cohen--Macaulay vertex cover ideal $J(G)$ has a Scarf minimal free resolution. Furthermore, by using both combinatorial and topological techniques, the…

Commutative Algebra · Mathematics 2024-04-05 Tài Huy Hà , Takayuki Hibi

The main aim of this paper is to characterize ideals I in the power series ring R=K[[x1,...,xs]] that are finitely determined up to contact equivalence by proving that this is the case if and only if I is an isolated complete intersection…

Algebraic Geometry · Mathematics 2019-05-09 Gert-Martin Greuel , Thuy Huong Pham

A fruitful contemporary paradigm in graph theory is that almost all graphs that do not contain a certain subgraph have common structural characteristics. The "almost" is crucial, without it there is no structure. In this paper we transfer…

Commutative Algebra · Mathematics 2023-10-09 Alexander Engström , Milo Orlich

An almost complete intersection ideal can be seen as a $d$-sequence ideal with the minimal number of generators being one more than its height. In this paper, we give exact formulas for the regularity of powers of graded almost complete…

Commutative Algebra · Mathematics 2024-12-02 Neeraj Kumar , Chitra Venugopal

Edge ideals of finite simple graphs are well-studied over polynomial rings. In this paper, we initiate the study of edge ideals over exterior algebras, specifically focusing on the depth and singular varieties of such ideals. We prove an…

Commutative Algebra · Mathematics 2022-08-09 Matthew Mastroeni , Jason McCullough , Andrew Osborne , Joshua Rice , Cole Willis

Let $G$ be a graph with $n$ vertices, $S=\mathbb{K}[x_1,\dots,x_n]$ be the polynomial ring in $n$ variables over a field $\mathbb{K}$ and $I(G)$ denote the edge ideal of $G$. For every collection $\mathcal{H}$ of connected graphs with…

Commutative Algebra · Mathematics 2017-05-30 Seyed Amin Seyed Fakhari , Siamak Yassemi

We construct the first linear strand of the minimal free resolutions of edge ideals of $d$-partite $d$-uniform clutters. We show that the first linear strand is supported on a relative simplicial complex. In the case that the edge ideals of…

Commutative Algebra · Mathematics 2020-12-07 Amin Nematbakhsh

We prove that, for the edge ideal of a cactus graph, the arithmetical rank is bounded above by the sum of the number of cycles and the maximum height of its associated primes. The bound is sharp, but in many cases it can be improved.…

Commutative Algebra · Mathematics 2017-03-28 Margherita Barile , Antonio Macchia

Let $G$ be a cycle or a complete bipartite graph. We show that the binomial edge ideal $J_{G}$ and its initial ideal with respect to the lexicographic order have the same extremal Betti number.

Commutative Algebra · Mathematics 2013-10-11 Ahmet Dokuyucu

For a finite simple graph $G$ we give an upper bound for the regularity of the powers of the edge ideal $I(G)$.

Commutative Algebra · Mathematics 2018-10-16 Jürgen Herzog , Takayuki Hibi

The regularity of an edge ideal of a finite simple graph $G$ is at least the induced matching number of $G$ and is at most the minimum matching number of $G$. If $G$ possesses a dominating inuduced matching, i.e., an induced matching which…

Combinatorics · Mathematics 2015-08-27 Takayuki Hibi , Akihiro Higashitani , Kyouko Kimura , Akiyoshi Tsuchiya

Let $I(G)$ be the edge ideal of a gapfree graph $G$. An open conjecture of Nevo and Peeva states that $I(G)^q$ has linear resolution for $q\gg 0$. We present a promising approach to this challenging conjecture by investigating the stronger…

Commutative Algebra · Mathematics 2024-12-24 Nursel Erey , Sara Faridi , Tài Huy Hà , Takayuki Hibi , Selvi Kara , Susan Morey

We introduce the concept of matching powers of monomial ideals. Let $I$ be a monomial ideal of $S=K[x_1,\dots,x_n]$, with $K$ a field. The $k$th matching power of $I$ is the monomial ideal $I^{[k]}$ generated by the products $u_1\cdots u_k$…

Commutative Algebra · Mathematics 2024-03-28 Nursel Erey , Antonino Ficarra

Let $\mathcal{D}$ be a weighted oriented graph and $I(\mathcal{D})$ be its edge ideal. In this paper, we investigate the Betti numbers of $I(\mathcal{D})$ via upper-Koszul simplicial complexes, Betti splittings and the mapping cone…

Commutative Algebra · Mathematics 2020-09-24 Beata Casiday , Selvi Kara

This paper presents exact formulas for the regularity and depth of powers of edge ideals of an edge-weighted star graph. Additionally, we provide exact formulas for the regularity of powers of the edge ideal of an edge-weighted integrally…

Commutative Algebra · Mathematics 2024-01-05 Guangjun Zhu , Shiya Duan , Yijun Cui , Jiaxin Li

We find a class of block graphs whose binomial edge ideals have minimal regularity. As a consequence, we characterize the trees whose binomial edge ideals have minimal regularity. Also, we show that the binomial edge ideal of a block graph…

Commutative Algebra · Mathematics 2014-02-11 Faryal Chaudhry , Ahmet Dokuyucu , Rida Irfan

We study minimal reductions of edge ideals of graphs and determine restrictions on the coefficients of the generators of these minimal reductions. We prove that when $I$ is not basic, then $\core{I}\subset \m I$, where $I$ is an edge ideal…

Commutative Algebra · Mathematics 2012-05-01 Louiza Fouli , Susan Morey

Let $R = \mathbb{K}[x_1, \ldots, x_n]$ and $I \subset R$ be a homogeneous ideal. In this article, we first obtain certain sufficient conditions for the subadditivity of $R/I$. As a consequence, we prove that if $I$ is generated by…

Commutative Algebra · Mathematics 2020-07-31 A. V. Jayanthan , Arvind Kumar