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We study the degree of non-homogeneous lattice ideals over arbitrary fields, and give formulae to compute the degree in terms of the torsion of certain factor groups of Z^s and in terms of relative volumes of lattice polytopes. We also…

Commutative Algebra · Mathematics 2014-03-24 Liam O'Carroll , Francesc Planas-Vilanova , Rafael H. Villarreal

Jerrum, Sinclair and Vigoda (2004) showed that the permanent of any square matrix can be estimated in polynomial time. This computation can be viewed as approximating the partition function of edge-weighted matchings in a bipartite graph.…

Discrete Mathematics · Computer Science 2021-06-25 Martin Dyer , Mark Jerrum , Haiko Muller , Kristina Vuskovic

In this paper we provide an asymptotic expansion for the number of independent sets in a general class of regular, bipartite graphs satisfying some vertex-expansion properties, extending results of Jenssen and Perkins on the hypercube and…

Combinatorics · Mathematics 2025-03-31 Maurício Collares , Joshua Erde , Anna Geisler , Mihyun Kang

In this paper, we introduce techniques for producing normal square-free monomial ideals from old such ideals. These techniques are then used to investigate the normality of cover ideals under some graph operations. Square-free monomial…

We generalize some results of $\mathrm{v}$-number for arbitrary monomial ideals by showing that the $\mathrm{v}$-number of an arbitrary monomial ideal is the same as the $\mathrm{v}$-number of its polarization. We prove that the…

Commutative Algebra · Mathematics 2022-03-04 Kamalesh Saha , Indranath Sengupta

In this paper we study the Alexander dual of a vertex decomposable simplicial complex. We define the concept of a vertex splittable ideal and show that a simplicial complex $\Delta$ is vertex decomposable if and only if $I_{\Delta^{\vee}}$…

Commutative Algebra · Mathematics 2016-08-24 Somayeh Moradi , Fahimeh Khosh-Ahang

We leverage an algorithm of Deming [R.W. Deming, Independence numbers of graphs -- an extension of the Koenig-Egervary theorem, Discrete Math., 27(1979), no. 1, 23--33; MR534950] to decompose a matchable graph into subgraphs with a precise…

Combinatorics · Mathematics 2022-05-24 P. Mark Kayll , Craig E. Larson

We extend the sortability concept to monomial ideals which are not necessarily generated in one degree and as an application we obtain normal Cohen-Macaulay toric rings attached to vertex cover ideals of graphs. Moreover, we consider a…

Commutative Algebra · Mathematics 2022-09-23 Jürgen Herzog , Takayuki Hibi , Somayeh Moradi

Let $\Lambda$ be a commutative Noetherian ring, and let $I$ be a proper ideal of $\Lambda$, $R=\Lambda /I$. Consider the polynomial rings $T=\Lambda [x_1,...x_n]$ and $A=R[x_1,...,x_n]$. Suppose that linear equations are solvable in…

Rings and Algebras · Mathematics 2012-07-04 Huishi Li

In a recent paper by Harada, Seceleanu, and \c{S}ega, the Hilbert function, betti table, and graded minimal free resolution of a general principal symmetric ideal are determined when the number of variables in the polynomial ring is…

Commutative Algebra · Mathematics 2026-04-21 Noah Walker

Let $X$ be an $(m\times n)$-matrix of indeterminates, and let $J$ be the ideal generated by a set $\mathcal{S}$ of maximal minors of $X$. We construct the linear strand of the resolution of $J$. This linear strand is determined by the…

Commutative Algebra · Mathematics 2015-09-01 Jürgen Herzog , Dariush Kiani , Sara Saeedi Madani

Let $G$ be a graph and let $J=I_c(G)$ be its ideal of covers. The aims of this work are to study the {\rm v}-number ${\rm v}(J)$ of $J$ and to study when $J$ is linearly presented using combinatorics and commutative algebra. We classify…

Commutative Algebra · Mathematics 2025-09-01 Humberto Muñoz-George , Enrique Reyes , Rafael H. Villarreal

Freiman's theorem gives a lower bound for the cardinality of the doubling of a finite set in $\RR^n$. In this paper we give an interpretation of his theorem for monomial ideals and their fiber cones. We call a quasi-equigenerated monomial…

Commutative Algebra · Mathematics 2018-01-17 Jürgen Herzog , Takayuki Hibi , Guangjun Zhu

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

Let $ X $ be an $ m \times n $ matrix of distinct indeterminates over a field $ K $, where $ m \le n $. Set the polynomial ring $ K[X] := K[X_{ij} : 1 \le i \le m, 1 \le j \le n] $. Let $ 1 \le k < l \le n $ be such that $ l - k + 1 \ge m…

Commutative Algebra · Mathematics 2026-03-02 Arindam Banerjee , Dipankar Ghosh , S. Selvaraja

We study monomial cut ideals associated to a graph $G$, which are a monomial analogue of toric cut ideals as introduced by Sturmfels and Sullivant. Primary decompositions, projective dimensions, and Castelnuovo-Mumford regularities are…

Commutative Algebra · Mathematics 2021-12-09 Jürgen Herzog , Masoomeh Rahimbeigi , Tim Römer

The Taylor resolution is almost never minimal for powers of monomial ideals, even in the square-free case. In this paper we introduce a smaller resolution for each power of any square-free monomial ideal, which depends only on the number of…

Commutative Algebra · Mathematics 2024-02-29 Susan M. Cooper , Sabine El Khoury , Sara Faridi , Sarah Mayes-Tang , Susan Morey , Liana M. Sega , Sandra Spiroff

In this paper, we study toric ideals associated with multichains of posets. It is shown that the comparability graph of a poset is chordal if and only if there exists a quadratic Gr\"obner basis of the toric ideal of the poset. Strong…

Combinatorics · Mathematics 2018-09-03 Hidefumi Ohsugi , Takayuki Hibi

We study the symbolic powers of square-free monomial ideals via symbolic Rees algebras and methods in prime characteristic. In particular, we prove that the symbolic Rees algebra and the symbolic associated graded algebra are split with…

Commutative Algebra · Mathematics 2019-07-29 Jonathan Montaño , Luis Núñez-Betancourt

Consider the rational map $\phi: \mathbb{P}^{n-1}_{\mathbf k} \stackrel{[f_0:\cdots: f_n]}{\longrightarrow} \mathbb{P}^{n}_{\mathbf k}$ defined by homogeneous polynomials $f_0,\dots,f_n$ of the same degree $d$ in a polynomial ring…

Commutative Algebra · Mathematics 2019-10-31 Youngsu Kim , Vivek Mukundan