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Twin-width is a recently introduced graph parameter with applications in algorithmics, combinatorics, and finite model theory. For graphs of bounded degree, finiteness of twin-width is preserved by quasi-isometry. Thus, through Cayley…

Group Theory · Mathematics 2022-07-18 Édouard Bonnet , Colin Geniet , Romain Tessera , Stéphan Thomassé

We prove a far-reaching strengthening of Szemer\'edi's regularity lemma for intersection graphs of pseudo-segments. It shows that the vertex set of such a graph can be partitioned into a bounded number of parts of roughly the same size such…

Combinatorics · Mathematics 2023-12-05 Jacob Fox , Janos Pach , Andrew Suk

Let $G$ be a connected graph. If $G$ contains a matching of size $k$, and every matching of size $k$ is contained in a perfect matching of $G$, then $G$ is said to be \emph{$k$-extendable}. A $k$-regular spanning subgraph of $G$ is called a…

Combinatorics · Mathematics 2022-11-18 Dandan Fan , Huiqiu Lin

We show the existence of length-constrained expander decomposition in directed graphs and undirected vertex-capacitated graphs. Previously, its existence was shown only in undirected edge-capacitated graphs [Haeupler-R\"acke-Ghaffari, STOC…

Data Structures and Algorithms · Computer Science 2025-04-01 Bernhard Haeupler , Yaowei Long , Thatchaphol Saranurak , Shengzhe Wang

An $n$-by-$n$ bipartite graph is $H$-saturated if the addition of any missing edge between its two parts creates a new copy of $H$. In 1964, Erd\H{o}s, Hajnal and Moon made a conjecture on the minimum number of edges in a…

Combinatorics · Mathematics 2014-11-27 Wenying Gan , Dániel Korándi , Benny Sudakov

We introduce a family of graphs, which we call down-left graphs, and study their combinatorial and algebraic properties. We show that members of this family are well-covered, $C_5$-free, and vertex decomposable. By applying a result of…

Commutative Algebra · Mathematics 2025-04-30 Jennifer Biermann , Beth Anne Castellano , Marcella Manivel , Eden Petrucelli , Adam Van Tuyl

Interval minors of bipartite graphs were introduced by Jacob Fox in the study of Stanley-Wilf limits. Recently, Mohar, Rafiey, Tayfeh-Rezaie and Wu investigated the maximum number of edges in $K_{k,\ell}$-interval minor free bipartite…

Combinatorics · Mathematics 2015-09-08 Yaping Mao , Hongjian Lai , Zhao Wang , Zhiwei Guo

We present an order-theoretic approach to the study of countably infinite locally 2-arc-transitive bipartite graphs. Our approach is motivated by techniques developed by Warren and others during the study of cycle-free partial orders. We…

Group Theory · Mathematics 2014-06-09 Robert D. Gray , John K. Truss

We prove that a fractional perfect matching in a non-bipartite graph can be written, in polynomial time, as a convex combination of perfect matchings. This extends the Birkhoff-von Neumann Theorem from bipartite to non-bipartite graphs. The…

Data Structures and Algorithms · Computer Science 2020-10-16 Vijay V. Vazirani

A graph is a split graph if its vertex set can be partitioned into a clique and a stable set. A split graph is unbalanced if there exist two such partitions that are distinct. Cheng, Collins and Trenk (2016), discovered the following…

Combinatorics · Mathematics 2017-06-13 Karen L. Collins , Ann N. Trenk

Ahmed, Bodwin, Sahneh, Kobourov, and Spence (WG 2020) introduced additive spanners for weighted graphs and constructed (i) a $+2W_{\max}$ spanner with $O(n^{3/2})$ edges and (ii) a $+4W_{\max}$ spanner with $\tilde{O}(n^{7/5})$ edges, and…

Data Structures and Algorithms · Computer Science 2024-08-28 An La , Hung Le

We study the polyhedral properties of three problems of constructing an optimal complete bipartite subgraph (a biclique) in a bipartite graph. In the first problem we consider a balanced biclique with the same number of vertices in both…

Combinatorics · Mathematics 2018-02-16 Vladimir Bondarenko , Andrei Nikolaev , Dzhambolet Shovgenov

In this paper, we exhibit an irreducible Markov chain $M$ on the edge $k$-colorings of bipartite graphs based on certain properties of the solution space. We show that diameter of this Markov chain grows linearly with the number of edges in…

Combinatorics · Mathematics 2023-02-07 Letong Hong , Istvan Miklos

We give an FPTAS for approximating the partition function of the hard-core model for bipartite graphs when there is sufficient imbalance in the degrees or fugacities between the sides $(L,R)$ of the bipartition. This includes, among others,…

Data Structures and Algorithms · Computer Science 2019-06-06 Sarah Cannon , Will Perkins

We introduce a new notation for representing labeled regular bipartite graphs of arbitrary degree. Several enumeration problems for labeled and unlabeled regular bipartite graphs have been introduced. A general algorithm for enumerating all…

Discrete Mathematics · Computer Science 2015-12-31 Vivek S. Nittoor

Structured prediction can be thought of as a simultaneous prediction of multiple labels. This is often done by maximizing a score function on the space of labels, which decomposes as a sum of pairwise and unary potentials. The above is…

Machine Learning · Computer Science 2021-02-19 Kevin Bello , Jean Honorio

The nearly complete bipartite graph $G(m,n,k)$ is obtained by removing $k$ independent edges from the complete bipartite graph $K_{m,n}$. In this paper, we prove that for any nearly complete bipartite graph $G(m,n,k)$ with $m, n\geq 3$, and…

Combinatorics · Mathematics 2026-01-13 Shengxiang Lv

This paper is devoted to present two counterexamples to the theorem from \cite{MK} Maria R., Katherine T. M., Bernardo S. M., Extremal graphs with bounded vertex bipartiteness number, Linear Algebra Appl. 493 (2016) 28-36. Moreover, the…

Combinatorics · Mathematics 2017-04-11 Jia-Bao Liu , Shaohui Wang

The graph polynomial for the number of independent sets of size $k$ in a general undirected graph is shown to be equal to an elementary symmetric polynomial of the vertex monomials, which are determined by the edges incident at the…

Combinatorics · Mathematics 2023-12-12 R. L. Streit

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