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Given a square-free monomial ideal $I$, we define a simplicial complex labeled by the generators of $I^2$ which supports a free resolution of $I^2$. As a consequence, we obtain (sharp) upper bounds on the Betti numbers of the second power…

We prove that the integral closures of the powers of a squarefree monomial ideal I equal the symbolic powers if and only if I is the edge ideal of a Fulkersonian hypergraph.

交换代数 · 数学 2007-05-23 Ngo Viet Trung

An ideal $I$ in a Noetherian ring is called \textit{normal} if $I^n$ is integrally closed for all $n \geq 1$. Zariski proved that in two-dimensional regular local rings, every integrally closed ideal is normal. However, in dimension three…

交换代数 · 数学 2026-02-03 Maki Ataka , Naoyuki Matsuoka

In this paper we study squarefree monomial ideals which have constant depth functions. Edge ideals, matroidal ideals and facet ideals of pure simplicial forests connected in codimension one with this property are classified.

交换代数 · 数学 2012-09-27 Jürgen Herzog , Marius Vladoiu

Given two finite sequences of positive integers $\alpha$ and $\beta$, we associate a square free monomial ideal $I_{\alpha,\beta}$ in a ring of polynomials $S$, and we recursively compute the algebraic invariants of $S/I_{\alpha,\beta}$.…

交换代数 · 数学 2018-05-28 Mircea Cimpoeas

The symbolic powers, in general, are not equal to the ordinary powers. Therefore, one interesting question here is for what classes of ideals ordinary and symbolic powers coincide? The answer to this question for squarefree monomial ideals…

交换代数 · 数学 2021-01-15 Ali Alilooee , Arindam Banerjee

We give a new combinatorial characterization of the big height of a squarefree monomial ideal leading to a new bound for the projective dimension of a monomial ideal.

交换代数 · 数学 2017-08-29 Nursel Erey

In this paper we consider monomial localizations of monomial ideals and conjecture that a monomial ideal is polymatroidal if and only if all its monomial localizations have a linear resolution. The conjecture is proved for squarefree…

交换代数 · 数学 2012-06-15 Somayeh Bandari , Jürgen Herzog

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…

交换代数 · 数学 2022-09-23 Jürgen Herzog , Takayuki Hibi , Somayeh Moradi

In this article, we study the squarefree powers of facet ideals associated with simplicial trees. Specifically, we examine the linearity of their minimal free resolution and their regularity. Additionally, we investigate when the first…

交换代数 · 数学 2026-01-26 Elshani Kamberi , Francesco Navarra , Ayesha Asloob Qureshi

We provide an algorithm that computes a set of generators for any complete ideal in a smooth complex surface. More interestingly, these generators admit a presentation as monomials in a set of maximal contact elements associated to the…

代数几何 · 数学 2017-10-31 Maria Alberich-Carramiñana , Josep Alvarez Montaner , Guillem Blanco

We introduce and study vertex cover algebras of weighted simplicial complexes. These algebras are special classes of symbolic Rees algebras. We show that symbolic Rees algebras of monomial ideals are finitely generated and that such an…

交换代数 · 数学 2007-05-23 Juergen Herzog , Takayuki Hibi , Ngo Viet Trung

We show that for a square-free monomial ideal, the regularity of its symbolic (second) power and of the integral closure of of its (second) power can differ from the regularity of its ordinary (second) power by an arbitrarily large integer.

交换代数 · 数学 2023-06-02 Irena Swanson , Siamak Yassemi

Let $S=K[x_1,\dots,x_n]$ be the polynomial ring over a field $K$ and $I\subset S$ be a squarefree monomial ideal generated in degree $n-2$. Motivated by the remarkable behavior of the powers of $I$ when $I$ admits a linear resolution, as…

交换代数 · 数学 2025-08-28 Antonino Ficarra , Somayeh Moradi

We introduce a specialization technique in order to study monomial ideals that are generated in degree two by using our earlier results about Ferrers ideals. It allows us to describe explicitly a cellular minimal free resolution of various…

交换代数 · 数学 2007-05-23 Alberto Corso , Uwe Nagel

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…

Let $I$ be a two-dimensional squarefree monomial ideal of a polynomial ring $S$. We evaluate the geometric regularity, $a_i$-invariants for $i\geq 1$ of the power $I^n$. It turns out they are all linear functions in $n$ from $n=2$.…

交换代数 · 数学 2020-02-20 Dancheng Lu

The free resolution and the Alexander dual of squarefree monomial ideals associated with certain subsets of distributive lattices are studied.

交换代数 · 数学 2007-05-23 Xinxian Zheng

To a simplicial complex, we associate a square-free monomial ideal in the polynomial ring generated by its vertex set over a field. We study algebraic properties of this ideal via combinatorial properties of the simplicial complex. By…

交换代数 · 数学 2007-05-23 Sara Faridi

We introduce the notion of sortability and $t$-sortability for a simplicial complex and study the graphs for which their independence complexes are either sortable or $t$-sortable. We show that the proper interval graphs are precisely the…

交换代数 · 数学 2019-08-21 Jürgen Herzog , Fahimeh Khosh-Ahang , Somayeh Moradi , Masoomeh Rahimbeigi