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We show that a simple Markov chain, the Glauber dynamics, can efficiently sample independent sets almost uniformly at random in polynomial time for graphs in a certain class. The class is determined by boundedness of a new graph parameter…

Discrete Mathematics · Computer Science 2020-12-07 Martin Dyer , Catherine Greenhill , Haiko Müller

Using the theory of combinatorial species, we compute the cycle index for bipartite graphs, which we use to count unlabeled bipartite graphs and bipartite blocks.

Combinatorics · Mathematics 2015-09-14 Andrew Gainer-Dewar , Ira M. Gessel

We present an algorithm for determining whether a bipartite graph $G$ is 2-chordal (formerly doubly chordal bipartite). At its core this algorithm is an extension of the existing efficient algorithm for determining whether a graph is…

Combinatorics · Mathematics 2021-04-13 Austin Alderete

In this paper, we give a lengthy proof of a small result! A graph is bisplit if its vertex set can be partitioned into three stable sets with two of them inducing a complete bipartite graph. We prove that these graphs satisfy the…

Discrete Mathematics · Computer Science 2023-06-22 Laurent Beaudou , Giacomo Kahn , Matthieu Rosenfeld

In this paper, we study a bipartite analogue of the `random graphs evolving by degrees' process. We are given a bipartitioned set of vertices $V$ into two disjoint parts ${L}$ and ${R}$ and possibly unequal positive constants $\alpha$ and…

Probability · Mathematics 2025-09-30 Neeladri Maitra

We prove that given a bipartite graph G with vertex set V and an integer k, deciding whether there exists a subset of V of size k hitting all maximal independent sets of G is complete for the class Sigma_2^P.

Computational Complexity · Computer Science 2015-05-12 Jean Cardinal , Gwenaël Joret

We show that the number of labelled $P_7$-free bipartite graphs with $n$ vertices grows as $n^{\Theta(n)}$. This resolves an open problem posed by Allen [P. Allen, Forbidden induced bipartite graphs. J. Graph Theory 60 (2009), no. 3,…

Combinatorics · Mathematics 2016-08-01 Vadim Lozin , Viktor Zamaraev

A set of edges $T$ in a graph $G$ is triangle-independent if $T$ contains at most one edge from each triangle in $G$. Let $\alpha_1(G)$ denote the maximum size of the triangle-independent set in $G$, and let $\tau_B(G)$ denote minimum size…

Combinatorics · Mathematics 2016-02-16 Sergey Norin , Yue Ru Sun

The independence polynomial $i(G,x)$ of a graph $G$ is the generating function of the numbers of independent sets of each size. A graph of order $n$ is very well-covered if every maximal independent set has size $n/2$. Levit and Mandrescu…

Combinatorics · Mathematics 2017-09-26 Jason I. Brown , Ben Cameron

In this paper, we propose a characterization of chordal bipartite graphs and an efficient enumeration algorithm for chordal bipartite induced subgraphs. A chordal bipartite graph is a bipartite graph without induced cycles with length six…

Data Structures and Algorithms · Computer Science 2020-09-23 Kazuhiro Kurita , Kunihiro Wasa , Hiroki Arimura , Takeaki Uno

Biregular bipartite graphs have been proven to have similar edge distributions to random bipartite graphs and thus have nice pseudorandomness and expansion properties. Thus it is quite desirable to find a biregular bipartite spanning…

Combinatorics · Mathematics 2024-10-29 Dandan Fan , Xiaofeng Gu , Huiqiu Lin

A graph is near-bipartite if its vertex set can be partitioned into an independent set and a set which induces a forest. In this paper, planar graphs without cycles of length from 4 to 7 are shown to be near-bipartite.

Combinatorics · Mathematics 2022-04-21 Lili Hao , Weihua Yang , Shuang Zhao

Let $k$ and $l$ be integers, both at least 2. A $(k,l)$-bipartite graph is an $l$-regular bipartite multigraph with coloured bipartite sets of size $k$. Define $\chi(k,l)$ and $\mu(k,l)$ to be the minimum and maximum order of automorphism…

Combinatorics · Mathematics 2025-10-06 Peter J. Cameron , Coen del Valle , Colva M. Roney-Dougal

In this paper, we classify the connected non-bipartite integral graphs with spectral radius three.

Combinatorics · Mathematics 2011-06-23 Taeyoung Chung , Jack Koolen , Yoshio Sano , Tetsuji Taniguchi

We show that every K_4-free graph G with n vertices can be made bipartite by deleting at most n^2/9 edges. Moreover, the only extremal graph which requires deletion of that many edges is a complete 3-partite graph with parts of size n/3.…

Combinatorics · Mathematics 2007-06-29 Benny Sudakov

In this paper, we investigate odd graceful graph, odd strongly harmonious graph, bipartite graph and their relationship. We proved following results: (1) if G is odd strongly harmonious graph, then G is odd graceful graph ;(2) if G is…

Combinatorics · Mathematics 2020-01-06 Xiuying Wang , Ying Zhoua , Haihong Wanga , Chunfeng Liu

It is known that complete multipartite graphs are determined by their distance spectrum but not by their adjacency spectrum. The Seidel spectrum of a graph $G$ on more than one vertex does not determine the graph, since any graph obtained…

Combinatorics · Mathematics 2019-02-08 Abraham Berman , Shaked-Monderer , Ranveer Singh , Xiao-Dong Zhang

Inspired by connections described in a recent paper by Mark L. Lewis, between the common divisor graph $\Ga(X)$ and the prime vertex graph $\Delta(X)$, for a set $X$ of positive integers, we define the bipartite divisor graph $B(X)$, and…

Combinatorics · Mathematics 2009-10-29 Mohammad A. Iranmanesh , Cheryl E. Praeger

A bipartite graph is chordal bipartite if every cycle of length at least 6 has a chord in it. In this paper, we investigate the structure of $P_5$-free chordal bipartite graphs and show that these graphs have a Nested Neighborhood Ordering,…

Discrete Mathematics · Computer Science 2017-12-27 S Aadhavan , P Renjith , N Sadagopan

Associated to a simple undirected graph G is a simplicial complex whose faces correspond to the independent sets of G. We call a graph G shellable if this simplicial complex is a shellable simplicial complex in the non-pure sense of…

Combinatorics · Mathematics 2007-11-06 Adam Van Tuyl , Rafael H. Villarreal