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We characterize the bipartite graphs that minimize the (first-degree based) entropy, among all bipartite graphs of given size, or given size and (upper bound on the) order. The extremal graphs turn out to be complete bipartite graphs, or…

Combinatorics · Mathematics 2022-06-03 Stijn Cambie , Yanni Dong , Matteo Mazzamurro

We give upper bounds for the Stanley depth of edge ideals of certain k-partite clutters. In particular, we generalize a result of Ishaq about the Stanley depth of the edge ideal of a complete bipartite graph. A result of Pournaki, Seyed…

Commutative Algebra · Mathematics 2017-08-25 Luis A. Dupont , Daniel G. Mendoza

Let $G$ be a finite simple graph and let $I_G$ denote its associated toric ideal in the polynomial ring $R$. For each integer $n\geq 2$, we completely determine all the possible values for the tuple $({\rm reg}(R/I_G), {\rm…

Commutative Algebra · Mathematics 2023-11-17 Kieran Bhaskara , Adam Van Tuyl

A $t$-bar visibility representation of a graph assigns each vertex up to $t$ horizontal bars in the plane so that two vertices are adjacent if and only if some bar for one vertex can see some bar for the other via an unobstructed vertical…

Combinatorics · Mathematics 2019-05-07 Weiting Cao , Douglas B. West , Yan Yang

An interval edge t-coloring of a graph G is a proper edge coloring of G with colors 1,2...,t such that at least one edge of G is colored by color i,i=1,2...,t, and the edges incident with each vertex v are colored by d_{G}(v) consecutive…

Discrete Mathematics · Computer Science 2007-12-30 Petros A. Petrosyan , Gagik H. Karapetyan

We study the regularity of binomial edge ideals. For a closed graph $G$ we show that the regularity of the binomial edge ideal $J_G$ coincides with the regularity of $\ini_{\lex}(J_G)$ and can be expressed in terms of the combinatorial data…

Commutative Algebra · Mathematics 2013-07-09 Viviana Ene , Andrei Zarojanu

We prove that for any toric ideal of a graph the degree of any element of Graver basis is bounded above by an exponential function of the maximal degree of a circuit.

Commutative Algebra · Mathematics 2017-12-08 Kamil Rychlewicz

Let $G$ be a simple connected non-complete graph and $J_G$ be its binomial edge ideal in a polynomial ring $S$. Using certain invariants associated to graphs, say $U(G)$, Banerjee and N\'{u}\~{n}ez-Betancourt gave an upper bound for the…

Commutative Algebra · Mathematics 2024-03-29 A. V. Jayanthan , Rajib Sarkar

Let $G$ be a finite simple graph on $n$ vertices and $J_G$ denote the corresponding binomial edge ideal in the polynomial ring $S = K[x_1, \ldots, x_n, y_1, \ldots, y_n].$ In this article, we compute the Hilbert series of binomial edge…

Commutative Algebra · Mathematics 2019-03-26 Arvind Kumar , Rajib Sarkar

We study the existence of perfect matchings in suitably chosen induced subgraphs of random biregular bipartite graphs. We prove a result similar to a classical theorem of Erdos and Renyi about perfect matchings in random bipartite graphs.…

Combinatorics · Mathematics 2013-09-10 Guillem Perarnau , Giorgis Petridis

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

In this article, I present a conjecture on the number of independent sets on graph covers. I also show that the conjecture implies that the partition function of a binary pairwise attractive model is greater than that of the Bethe…

Combinatorics · Mathematics 2011-10-18 Yusuke Watanabe

Ricci curvature was proposed by Ollivier in a general framework of metric measure spaces, and it has been studied extensively in the context of graphs in recent years. In this paper we prove upper bounds for Ollivier's Ricci curvature for…

Combinatorics · Mathematics 2020-08-25 Bhaswar B. Bhattacharya , Sumit Mukherjee

In this paper, we provide an method to obtain the lower bound on the number of the distinct maximum genus embedding of the complete bipartite graph Kn;n (n be an odd number), which, in some sense, improves the results of S. Stahl and H.…

Combinatorics · Mathematics 2012-03-06 Guanghua Dong , Han Ren , Ning Wang , Yuanqiu Huang

We introduce a persistent commutative algebra for studying the algebraic and combinatorial evolution of edge ideals of graphs and hypergraphs under filtration. Building on the Persistent Stanley--Reisner Theory (PSRT), we develop the notion…

Commutative Algebra · Mathematics 2025-12-22 Faisal Suwayyid , Guo-Wei Wei

In this article we obtain an improved upper bound for the regularity of binomial edge ideals of trees.

Commutative Algebra · Mathematics 2018-08-21 A. V. Jayanthan , N. Narayanan , B. V. Raghavendra Rao

We give an upper bound on the number of perfect matchings in simple graphs with a given number of vertices and edges. We apply this result to give an upper bound on the number of 2-factors in a directed complete bipartite balanced graph on…

Combinatorics · Mathematics 2014-08-01 M. Aaghabali , S. Akbari , S. Friedland , K. Markstrom , Z. Tajfirouz

We show that the signature of a positive braid link is bounded from below by one-quarter of its first Betti number. This equates to one-half of the optimal bound conjectured by Feller, who previously provided a bound of one-eighth.

Geometric Topology · Mathematics 2025-12-15 Joshua Evan Greene , Livio Liechti

A $\frac{1}{k}$-majority $l$-edge-colouring of a graph $G$ is a colouring of its edges with $l$ colours such that for every colour $i$ and each vertex $v$ of $G$, at most $\frac{1}{k}$'th of the edges incident with $v$ have colour $i$. We…

Combinatorics · Mathematics 2023-09-29 Paweł Pękała , Jakub Przybyło

In this paper, we investigate the arithmetical rank of a binomial ideal $J$. We provide lower bounds for the binomial arithmetical rank and the $J$-complete arithmetical rank of $J$. Special attention is paid to the case where $J$ is the…

Commutative Algebra · Mathematics 2017-09-19 Anargyros Katsabekis