Hiroju Kanno
In this paper, we define (im, reg)-invariant extension of graphs and propose a new approach for Nevo and Peeva's conjecture which said that for any gap-free graph $G$ with $reg(I(G)) = 3$ and for any $k \geq 2$, $I(G)^k$ has a linear resolution. Moreover, we consider new conjectures related to the regularity of powers of edge ideals of gap-free graphs.
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Castelnuovo-Mumford regularity is a measure of algebraic complexity of an ideal. Regularity of monomial ideals can be investigated combinatorially. We use a simple graph decomposition and results from structural graph theory to prove, improve and generalize many of the known bounds on regularity of quadratic square-free monomial ideals.
Regularity of edge ideals of powers of graphs
本文研究图的幂的边理想的正则性，证明了森林的幂的边理想正则性弱递减，并计算了圈的幂的边理想正则性。
Depth and regularity of tableau ideals
本文计算了表格理想的深度和正则度，这些理想由正整数填充杨图定义。
We study join-meet ideals associated with modular non-distributive lattices. We give a lower bound for the regularity and show that they are not linearly related.
Binomial edge ideals of regularity $3$
设$J_G$是图$G$的二项式边理想.我们刻画了所有图的二项式边理想，以及他们的初始理想，有正则性$3$。因此，我们刻画了所有图$G$，使得$J_G$是极值Gorenstein。事实上，这些特征的后果，我们得到的一个明确的公式的正则性二项式边理想的两个图的连接产品。最后，利用我们的正则性公式，讨论了文献中的一些公开问题。特别是我们反驳了\cite{CDI}中关于弱闭图的正则性的一个猜想。
Some inequalities regarding the regularity of powers of monomial ideals
本文研究单项式理想幂的正则性，证明了其符号幂与幂的整闭包的 Castelnuovo–Mumford 正则性所满足的若干不等式。
Regularity of normal Rees algebras of edge ideals of graphs
本研究针对图的边理想的正规Rees代数，分类了所有满足代数正规且正则性与图的匹配数相等的图，完善了交换代数与图论交叉领域的相关结论。
We obtain an improved lower bound for the regularity of the binomial edge ideals of trees. We prove an upper bound for the regularity of the binomial edge ideals of certain subclass of block-graphs. As a consequence we obtain sharp upper and lower bounds for the regularity of binomial edge ideals of a class of trees called lobsters. We also obtain precise expressions for the regularities of binomial edge ideals of certain classes of trees and block graphs.
Regularity and depth of binomial ideals arising from combinatorics
研究组合学中由相邻2-子式及有限格产生的二项式理想的正则性与深度。
Critical subgraphs and the regularity of symbolic powers of cover ideals of graphs
本文通过t-可接受子图确定图的覆盖理想t次符号幂的正则性，并应用于双部单环图的覆盖理想幂的正则性计算。
Regularity, Depth and Arithmetic Rank of Bipartite Edge Ideals
研究了二部图的边理想的极小自由分解。将有向图与边理想为纯的二部图联系起来，利用有向图的不变量给出了边理想的正则性和深度的表达式.对于某些类的非混合边理想，我们证明了理想的算术秩等于其商的投射维数。
We give a lower bound for the Castelnuovo-Mumford regularity of binomial edge ideals of block graphs by computing the two distinguished extremal Betti numbers of a new family of block graphs, called flower graphs. Moreover, we present a linear time algorithm to compute the Castelnuovo-Mumford regularity and Krull dimension of binomial edge ideals of block graphs.
Regularity of edge ideal of a graph
在本文中，我们介绍了一些约化过程的图，保持相关的边理想的正则性。从而给出了R.给出了Fröberg关于图的边理想的分解的线性性定理。
Hypergraphs and the Regularity of Square-free Monomial Ideals
我们定义了一个新的组合对象，我们称之为一个标记超图，唯一关联到任何平方自由单项式理想。本文利用无平方单项式理想的标号超图的简单组合性质，证明了其正则性的几个上界。我们还给出了无平方单项式理想与某些标号超图的正则性的具体公式。此外，我们证明了结果的情况下，一维标记超图。
(Generalized) binomial edge ideals and their regularity
本文综述二项式边理想及广义二项式边理想的Castelnuovo-Mumford正则性研究进展，并将已知上界推广至广义情形。
The Regularity of Powers of Edge Ideals
本文证明了任意图的边理想的幂的极小单项生成元集上的一个特殊序的存在性。利用这个序，我们找到了补图没有诱导四圈的图的边理想的幂的正则性的新的上界。
The Castelnuovo-Mumford regularity of binomial edge ideals
证明了Matsuda和Murai关于图的二项式边理想的Castelnuovo-Mumford正则性的一个严格的上界。证明了对于任何具有非路的$n$顶点的图$G$，都有$\mathrm{reg}(J_G)\leq n-1$，并且研究了图的联积下的二项式边理想的正则性。
We define the Eulerian ideal of a $k$-uniform hypergraph and study its degree and Castelnuovo--Mumford regularity. The main tool is a Gröbner basis of the ideal obtained combinatorially from the hypergraph. We define the notion of parity join in a hypergraph and show that the regularity of the Eulerian ideal is equal to the maximum cardinality of such a set of edges. The formula for the degree involves the cardinality of the set of sets of vertices, $T$, that admit a $T$-join. We compute the degree and regularity explicity in the cases of a complete $k$-partite hypergraph and a complete hyperg…
In this paper we introduce the concept of clique disjoint edge sets in graphs. Then, for a graph $G$, we define the invariant $η(G)$ as the maximum size of a clique disjoint edge set in $G$. We show that the regularity of the binomial edge ideal of $G$ is bounded above by $η(G)$. This, in particular, settles a conjecture on the regularity of binomial edge ideals in full generality.
Bounds on the Stanley depth and Stanley regularity of edge ideals of clutters
设$I$是多项式环$S$中杂波$\mathcal{C}$的边理想。在本文中，我们提出了估计的斯坦利深度的$I$以及斯坦利规律的$S/I$，在组合数据的杂波$\mathcal{C}$。
We study the Castelnuovo-Mumford regularity of powers of edge ideals. We prove that if G is a bipartite graph, then reg(I(G)^s) \leq 2s + reg I(G) - 2 for all s \geq 2, which is the best possible upper bound for any s. Suspension plays a key role in proof of the base case s =2.
In this paper we use polarization to study the behavior of the depth and regularity of a monomial ideal $I$, locally at a variable $x_i$, when we lower the degree of all the highest powers of the variable $x_i$ occurring in the minimal generating set of $I$, and examine the depth and regularity of powers of edge ideals of clutters using combinatorial optimization techniques. If $I$ is the edge ideal of an unmixed clutter with the max-flow min-cut property, we show that the powers of $I$ have non-increasing depth and non-decreasing regularity. In particular edge ideals of unmixed bipartite grap…
We survey recent studies on the Castelnuovo-Mumford regularity of edge ideals of graphs and their powers. Our focus is on bounds and exact values of $\text{reg} I(G)$ and the asymptotic linear function $\text{reg} I(G)^q$, for $q \geq 1,$ in terms of combinatorial data of the given graph $G.$
Bounds on the regularity and projective dimension of ideals associated to graphs
在本文中，我们给出了新的上界的正则性的边缘理想的决议是k-步骤的线性，令人惊讶的是，界的对数的变量的数量。我们也给出了各种界限的投射维数这样的理想，推广了其他最近的结果。通过Alexander对偶，我们的结果也适用于余维为2的非混合无平方项理想。我们也讨论和连接这些结果在交换代数更经典的主题。
Regularity of powers of edge ideal of whiskered cycles
设$G=W(C_{n})$是具有边理想$I=I(G)$的须圈图.我们证明了对于每个$s\geq 1$，等式${\rm reg}(I^{s})=2s+\lceil \frac{n-1}{2}\rceil-1$成立。
Let $G$ be a simple graph on $n$ vertices and $J_G$ denote the corresponding binomial edge ideal in $S = K[x_1, \ldots, x_n, y_1,\ldots, y_n].$ We prove that the Castelnuovo-Mumford regularity of $J_G$ is bounded above by $c(G)+1$ when $G$ is a quasi-block graph or semi-block graph. We give another proof of Saeedi Madani-Kiani regularity upper bound conjecture for chordal graphs. We obtain the regularity of binomial edge ideals of Jahangir graphs. Later, we establish a sufficient condition for Hibi-Matsuda conjecture to be true.
Let $I$ and $J$ be edge ideals in a polynomial ring $R = \mathbb{K}[x_1,\ldots,x_n]$ with $I \subseteq J$. In this paper, we obtain a general upper and lower bound for the Castelnuovo-Mumford regularity of $IJ$ in terms of certain invariants associated with $I$ and $J$. Using these results, we explicitly compute the regularity of $IJ$ for several classes of edge ideals. Let $J_1,\ldots,J_d$ be edge ideals in a polynomial ring $R$ with $J_1 \subseteq \cdots \subseteq J_d$. Finally, we compute the precise expression for the regularity of $J_1 J_2\cdots J_d$ when $d \in \{3,4\}$ and $J_d$ is the …
Castelnuovo-Mumford regularity of generalized binomial edge ideals of graphs
本文研究图的广义二项式边理想的正则度，证明其范围为2到n-1，并给出P4-free图的新特征化。
Let $G$ be a unicyclic graph with edge ideal $I(G)$. For any integer $s\geq 1$, we denote the $s$-th symbolic power of $I(G)$ by $I(G)^{(s)}$. It is shown that ${\rm reg}(I(G)^{(s)})={\rm reg}(I(G)^s)$, for every $s\geq 1$.
For a polynomial ring S in n variables, we consider the natural action of the symmetric group S_n on S by permuting the variables. For an S_n-invariant monomial ideal I in S and j >= 0, we give an explicit recipe for computing the modules Ext^j(S/I,S), and use this to describe the projective dimension and regularity of I. We classify the S_n-invariant monomial ideals that have a linear free resolution, and also characterize those which are Cohen-Macaulay. We then consider two settings for analyzing the asymptotic behavior of regularity: one where we look at powers of a fixed ideal I, and anoth…
Regularity of powers of d-sequence (parity) binomial edge ideals of unicycle graphs
本文分类了单圈图中边缘二项式构成d-序列的图，并研究其（奇偶）二项式边缘理想的幂的正则度。
The regularity of binomial edge ideals of graphs
本文证明了几类图的二项式边理想的Castelnuovo-Mumford正则性的上界的两个新结果。本文证明了Matsuda和Murai关于有割边或单纯顶点的图的猜想，从而也证明了弦图的猜想。本文利用原图的正则性，确定了图的联的二项式边理想的正则性，从而证明了Matsuda和Murai关于这类图的猜想，进而证明了完全$t$ -部图的猜想.我们还推广了Schenzel和Zafar关于完全$t$ -部图的一些结果.对于一类弦图，我们也证明了作者的猜想。
D-Sequence Edge Binomials, and Regularity of Powers of Binomial Edge Ideals of Trees
本文以图的度序列为依据，给出了树的边二项式构成 $d$-序列的充要条件，并研究了由 $d$-序列边二项式生成的树的二项式边理想幂的正则性。
Let $G$ be a finite simple graph and $I(G)$ denote the corresponding edge ideal. In this paper, we obtain upper bounds for the Castelnuovo-Mumford regularity of $I(G)^q$ in terms of certain combinatorial invariants associated with $G$. We also prove a weaker version of a conjecture by Alilooee, Banerjee, Beyarslan and Hà on an upper bound for the regularity of $I(G)^q$ and we prove the conjectured upper bound for the class of vertex decomposable graphs. Using these results, we explicitly compute the regularity of $I(G)^q$ for several classes of graphs.
Let $I = I(G)$ be the edge ideal of a graph $G$. We give various general upper bounds for the regularity function $\text{reg} I^s$, for $s \ge 1$, addressing a conjecture made by the authors and Alilooee. When $G$ is a gap-free graph and locally of regularity 2, we show that $\text{reg} I^s = 2s$ for all $s \ge 2$. This is a slightly weaker version of a conjecture of Nevo and Peeva. Our method is to investigate the regularity function $\text{reg}I^s$, for $s \ge 1$, via local information of $I$.
Let $D$ be a weighted oriented graph with the underlying graph $G$ and $I(D), I(G) $ be the edge ideals corresponding to $D$ and $G$ respectively. We show that the regularity of edge ideal of a certain class of weighted oriented graph remains same even after adding certain kind of new edges to it. We also establish the relationship between the regularity of edge ideal of weighted oriented path and cycle with the regularity of edge ideal of their underlying graph when vertices of $V^+$ are sinks.
Some Remarks on Ideals with large Regularity and Regularity Jumps
本文给出了多项式环中齐次理想的Castelnuovo-Mumford正则性的一些新的例子。更确切地说，我们提出了新的例子，齐次理想与大的正则性相比，生成度。然后我们考虑了理想的正则跳。特别是，我们提供了一个无限家庭的理想有规律性的跳跃在一定的权力。
In this paper we prove the conjectured upper bound for Castelnuovo-Mumford regularity of binomial edge ideals posed in [23], in the case of chordal graphs. Indeed, we show that the regularity of any chordal graph G is bounded above by the number of maximal cliques of G, denoted by c(G). Moreover, we classify all chordal graphs G for which L(G) = c(G), where L(G) is the sum of the lengths of longest induced paths of connected components of G. We call such graphs strongly interval graphs. Moreover, we show that the regularity of a strongly interval graph G coincides with L(G) as well as c(G).
Regularity 3 in edge ideals associated to bipartite graphs
本文主要研究与二部图相关的边理想，并给出正则度为3的边理想的组合刻画。当正则性严格大于3时，我们确定了最小分次自由分解的第一步$i$，其中存在一个度为$>i+3$的最小生成元，证明了在这一步最小生成元的最高度为$i+4$，并根据相应的二部图的组合学确定了相应的分次贝蒂数$β_{i,i+4}$的值.结果可以很容易地通过极化推广到非平方自由的情况。我们还研究了一类正则4的理想族，这类理想在我们的主要结果中起着重要作用，并且其分次贝蒂数可以完全通过封闭的组合公式来描述。
Let $G$ be a bipartite graph and $I=I(G)$ be its edge ideal. The aim of this note is to investigate different aspects of the Rees algebra $\mathcal{R}(I)$ of $I$. We compute its regularity and the universal Gröbner basis of its defining equations; interestingly, both of them are described in terms of the combinatorics of $G$. We apply these ideas to study the regularity of the powers of $I$. For any $s \ge \text{match}(G)+\lvert E(G) \rvert +1$ we prove that $\text{reg}(I^{s+1})=\text{reg}(I^s)+2$.
For any two integers $d,r \geq 1$, we show that there exists an edge ideal $I(G)$ such that the ${\rm reg}\left(R/I(G)\right)$, the Castelnuovo-Mumford regularity of $R/I(G)$, is $r$, and ${\rm deg} (h_{R/I(G)}(t))$, the degree of the $h$-polynomial of $R/I(G)$, is $d$. Additionally, if $G$ is a graph on $n$ vertices, we show that ${\rm reg}\left(R/I(G)\right) + {\rm deg} (h_{R/I(G)}(t)) \leq n$.
Regularity of Powers of edge ideal of very well-covered graphs
令$k\geq 3$为整数，$G$为具有${\rm odd-girth}(G)\geq 2k+1$的覆盖良好的图。假设$I(G)$是$G$的边理想。我们证明了对于每一个具有$1\leq s\leq k-2$的整数$s$，我们有${\rm reg}(I(G)^s)=2s+ν(G)-1$，其中$ν(G)$是$G$的诱导匹配数。
Results on the regularity of square-free monomial ideals
在2008年的一篇论文中，第一作者和Van Tuyl证明了图G的边理想的正则性至多比G的匹配数大大于一。在本文中，我们将这个结果推广到任何无平方根的单项理想。我们定义一个简单超图中的2-拼贴是一个边的集合，其性质是对于超图的任何边E，拼贴中存在一条边F，使得|英、法|< 2。简单超图的边理想的Castelnuovo-Mumford正则性被2-拼贴的最小尺寸的倍数上界。我们还给出了一个计算点可分解超图正则性的递归公式。最后，我们证明了在图的情况下，正则性是有界的基于非退化星形子图的最大填装的一定的统计。
We study the relationship between depth and regularity of a homogeneous ideal I and those of (I,f) and I:f, where f is a linear form or a monomial. Our results has several interesting consequences on depth and regularity of edge ideals of hypegraphs and of powers of ideals.
Assume that $G$ is a graph with edge ideal $I(G)$. For every integer $s\geq 1$, we denote the squarefree part of the $s$-th symbolic power of $I(G)$ by $I(G)^{\{s\}}$. We determine an upper bound for the regularity of $I(G)^{\{s\}}$ when $G$ is a chordal graph. If $G$ is a Cameron-Walker graphs, we compute ${\rm reg}(I(G)^{\{s\}}$ in terms of the induced matching number of $G$. Moreover, for any graph $G$, we provide sharp upper bounds for ${\rm reg}(I(G)^{\{2\}})$ and ${\rm reg}(I(G)^{\{3\}})$.
Regularity of symbolic powers of cover ideals of graphs
设$G$是一个图，它属于下列任一类：（i）二部图，（ii）纯图，或（iii）无爪图.假设$J(G)$是覆盖理想$G$，而$J(G)^{(k)}$是它的$k$次符号幂。我们证明了$$k{\rm deg}(J(G))\leq {\rm reg}(J(G)^{(k)})\leq (k-1){\rm deg}(J(G))+|V(G)|-1.$$。我们还确定了图族的上述不等式是平等的。
Regularity of joint-meet ideals of distributive lattices
设$L$是分配格，$R(L)$是相应的Hibi环.当$L$是平面格时，我们计算了$\reg R(L)$;当$L$是非平面格时，我们利用$L.$的组合数据，给出了$\reg R(L)$的一个下界.
Dominating induced matchings of finite graphs and regularity of edge ideals
有限单图$G$的边理想的正则性至少是$G$的导出匹配数，至多是$G$的最小匹配数.如果$G$具有支配诱导匹配，即，形成最大匹配的诱导匹配，则$G$的诱导匹配数等于$G$的最小匹配数。本文从组合数学和交换代数的角度出发，主要研究具有控制诱导匹配的有限单图。
A Cameron-Walker graph is a graph for which the matching number and the induced matching number are the same. Assume that $G$ is a Cameron-Walker graph with edge ideal $I(G)$, and let $\ind-match(G)$ be the induced matching number of $G$. It is shown that for every integer $s\geq 1$, we have the equality ${\rm reg}(I(G)^{(s)})=2s+\ind-match(G)-1$, where $I(G)^{(s)}$ denotes the $s$-th symbolic power of $I(G)$.
On the Castelnuovo-Mumford regularity of products of ideal sheaves
本文给出了理想与理想层乘积的Castelnuovo-Mumford正则性的界。特别地，我们证明了，如果相应的计划相交于一个有限集的点，则理想的理想的积的正则性是有界的。我们还展示了如何近似层可以用来约束的规则性安排的两个平面在射影空间。
We determine the Castelnuovo-Mumford regularity of binomial edge ideals of complement reducible graphs (cographs). For cographs with $n$ vertices the maximum regularity grows as $2n/3$. We also bound the regularity by graph theoretic invariants and construct a family of counterexamples to a conjecture of Hibi and Matsuda.
Regularity of ideals of Borel type is linearly bounded
证明了其相伴素理想是全序包含的单项式理想的正则性是线性有界的。
Regularity of powers of cover ideals of unimodular hypergraphs
设$\H$是顶点集$[n]$上的幺模超图，$J(\H)$是多项式环$R=K[x_1,\ldots,x_n]$中$\H$的覆盖理想.我们发现，$\reg J(\H)^s$是一个线性函数，在$s$的所有$s\geqslant r\left\lceil \frac{n}{2}\right\rceil+1$，其中$r$是排名的$\H$。此外，对于每个$i$，$a_i(R/J(\H)^s)$也是$s$中对于$s \geqslant n^2$的线性函数。
Regularity and projective dimension of edge ideal of $C_5$-free vertex decomposable graphs
本文用图的不变量解释了几类图的正则性、投射维数和边理想深度。我们证明了对于一个无$C_5$的顶点可分解图$G$，$\T{reg}(R/I(G))= c_G$，其中$c_G$是$G$中3-不相交边的最大个数.此外，对于这类图，我们刻画了$\T{pd}(R/I(G))$和$\T{depth}(R/I(G))$。作为推论，我们在森林和序列Cohen-Macaulay二部图中描述了这些不变量。
Bounds for the regularity of edge ideal of vertex decomposable and shellable graphs
本文利用图的不变量给出了几类图的边理想正则性的上界。引入了两个依赖于图$G$的数$a'(G)$和$n(G)$，并证明了对于顶点可分解图$G$，$a'(G)$和$n(G)$分别为$\reg(R/I(G))\leq \min\{a'(G),n(G)\}$和$\reg(R/I(G))\leq n(G)$ .此外，它表明，对于图$G$，其中$G^c$是$d$树，我们有$\pd(R/I(G))=\max_{v\in V(G)} \{°_G(v)\}$。
Regularity for certain classes of monomial ideals
我们引入了一类新的单项理想，称为强Borel型理想，并计算了主强Borel型理想的Mumford-Castelnouvo正则性。此外，我们描述了d-固定的理想所产生的权力的变量，我们计算他们的正则性。
Regularity of two classes of Cohen-Macaulay binomial edge ideals
本文针对带须的圈链和带须的$r$-正则$r$-连通块两类Cohen-Macaulay二项式边理想，给出Castelnuovo-Mumford正则性的显式组合公式，并引入基于诱导块图块数的新不变量。
Regularity of Symbolic Powers of Co-Chordal Edge Ideals
该研究针对有限简单余弦图的边理想，证明其符号幂的正则性公式为reg I(G)^(s)=2s，还指出这类符号幂未必是分量wise线性的，归约与论证过程结合了Takayama公式、团树等方法。
(Almost) Complete Intersection Lovász-Saks-Schrijver ideals and regularity of their powers
本文研究了特定图类的 LSS-理想完全交集性质，并引入了 twisted 正则匹配分解数来判断其完全交集条件。
Powers of edge ideals of regularity three bipartite graphs
本文证明了：若$I(G)$是正则性为3的二部边理想，则对所有的$s\geq 2$，$I(G)^s$的正则性恰为$2s+1$ .
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