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Let $G$ be a simple graph on $n$ vertices. Let $L_G \text{ and } \mathcal{I}_G \: $ denote the Lov\'asz-Saks-Schrijver(LSS) ideal and parity binomial edge ideal of $G$ in the polynomial ring $S = \mathbb{K}[x_1,\ldots, x_n, y_1, \ldots,…

Commutative Algebra · Mathematics 2021-12-07 Arvind Kumar

In this paper, we study the Hankel edge ideals of graphs. We determine the minimal prime ideals of the Hankel edge ideal of labeled Hamiltonian and semi-Hamiltonian graphs, and we investigate radicality, being a complete intersection,…

Commutative Algebra · Mathematics 2022-05-13 Dariush Kiani , Sara Saeedi Madani , Saeed Tafazolian

We introduce the concept of minimum edge cover for an induced subgraph in a graph. Let $G$ be a unicyclic graph with a unique odd cycle and $I=I(G)$ be its edge ideal. We compute the exact values of all symbolic defects of $I$ using the…

Commutative Algebra · Mathematics 2022-04-13 Mousumi Mandal , Dipak Kumar Pradhan

We compute the multigraded Betti numbers of edge ideals for weighted oriented crown graphs using a novel approach. This approach, which we still call the \emph{induced subgraph approach}, originates from our prior work on computing Betti…

Commutative Algebra · Mathematics 2025-05-13 Zexin Wang , Dancheng Lu

We collect some general results on graph limits associated to hereditary classes of graphs. As examples, we consider some classes defined by forbidden subgraphs and some classes of intersection graphs, including triangle-free graphs,…

Combinatorics · Mathematics 2013-03-29 Svante Janson

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

We provide a closed formula for the graded Betti numbers in the linear strands of all powers of binomial edge ideals $J_G$ arising from closed graphs $G$ that do not have the complete graph $K_4$ as an induced subgraph. We show that these…

Commutative Algebra · Mathematics 2026-01-19 Abbas Dohadwala , Bryan Flores-Silva , Alicia Orozco-Moya , Zoe Siegelnickel

We define and study a special type of hypergraph. A $\sigma$-hypergraph $H= H(n,r,q$ $\mid$ $\sigma$), where $\sigma$ is a partition of $r$, is an $r$-uniform hypergraph having $nq$ vertices partitioned into $ n$ classes of $q$ vertices…

Combinatorics · Mathematics 2014-07-21 Christina Zarb

We study the distributional properties of horizontal visibility graphs associated with random restrictive growth sequences and random set partitions of size $n.$ Our main results are formulas expressing the expected degree of graph nodes in…

Combinatorics · Mathematics 2019-12-12 Toufik Mansour , Reza Rastegar , Alexander Roitershtein

Let $G$ be a simple graph on $n$ vertices, and let $J_G$ denotes the corresponding binomial edge ideal in $S=\mathbb{K}[x_1,\ldots,x_n,y_1,\ldots,y_n]$, where $\mathbb{K}$ is a field. We show that if a vertex satisfies a certain degree…

Commutative Algebra · Mathematics 2025-12-03 Kanoy Kumar Das , Rajiv Kumar , Paramhans Kushwaha

Let $H$ and $G$ be graphs such that $H$ has at least 3 vertices and is connected. The $H$-line graph of $G$, denoted by $HL(G)$, is that graph whose vertices are the edges of $G$ and where two vertices of $HL(G)$ are adjacent if they are…

Combinatorics · Mathematics 2022-07-29 Alvaro Carbonero

In this article we study higher homological properties of $n$-levelled algebras and connect them to properties of the underlying graphs. Notably, to each $2$-representation-finite quadratic monomial algebra $\Lambda$ we associate a…

Representation Theory · Mathematics 2024-11-04 Karin M. Jacobsen , Mads Hustad Sandøy , Laertis Vaso

The geometric thickness of a graph G is the minimum integer k such that there is a straight line drawing of G with its edge set partitioned into k plane subgraphs. Eppstein [Separating thickness from geometric thickness. In: Towards a…

Combinatorics · Mathematics 2007-05-23 Janos Barat , Jiri Matousek , David R. Wood

Let $G$ be a finite simple graph and $I(G)$ denote the corresponding edge ideal. For all $s \geq 1$, we obtain upper bounds for reg$(I(G)^s)$ for bipartite graphs. We then compare the properties of $G$ and $G'$, where $G'$ is the graph…

Commutative Algebra · Mathematics 2016-09-07 A V Jayanthan , N Narayanan , S Selvaraja

A hypergraph $G=(V,E)$ is $(k,\ell)$-sparse if no subset $V'\subset V$ spans more than $k|V'|-\ell$ hyperedges. We characterize $(k,\ell)$-sparse hypergraphs in terms of graph theoretic, matroidal and algorithmic properties. We extend…

Combinatorics · Mathematics 2007-06-13 Ileana Streinu , Louis Theran

We establish tight lower and upper bounds on the number of edges in traceable graphs in several classes of dense graphs. A graph is traceable if it has a Hamiltonian path. We show that the bound is: - quadratic for the class of graphs of…

Combinatorics · Mathematics 2025-09-03 Michal Dvořák , Dušan Knop , Michal Opler , Jan Pokorný , Ondřej Suchý , Krisztina Szilágyi

Let $I_G$ be the binomial edge ideal on the generic 2 x n - Hankel matrix associated with a closed graph $G$ on the vertex set [n]. We characterize the graphs $G$ for which $I_G$ has maximal regularity and is Gorenstein.

Commutative Algebra · Mathematics 2015-12-02 Ahmet Dokuyucu , Ajdin Halilovic , Rida Irfan

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

We give several results showing that different discrete structures typically gain certain spanning substructures (in particular, Hamilton cycles) after a modest random perturbation. First, we prove that adding linearly many random edges to…

Combinatorics · Mathematics 2018-03-23 Michael Krivelevich , Matthew Kwan , Benny Sudakov

We relate homological properties of a binomial edge ideal $\mathcal{J}_G$ to invariants that measure the connectivity of a simple graph $G$. Specifically, we show if $R/\mathcal{J}_G$ is a Cohen-Macaulay ring, then graph toughness of $G$ is…

Commutative Algebra · Mathematics 2016-05-03 Arindam Banerjee , Luis Núñez-Betancourt