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We propose a random bipartite graph with weights assigned to both parts of the vertex sets. Edges are formed independently with probabilities that depend on these weights. This bipartite graph naturally gives rise to a random intersection…

Probability · Mathematics 2025-06-10 Alastair Haig , Minmin Wang

Let $G$ be a graph with vertex set $V(G)$ and edge set $E(G)$, and $f$ be a 0-1 labeling of $E(G)$ so that the absolute difference in the number of edges labeled 1 and 0 is no more than one. Call such a labeling $f$ \emph{edge-friendly}.…

Combinatorics · Mathematics 2011-06-07 Elliot Krop , Keli Sikes

In this work, we present the first local-decoding algorithm for expander codes. This yields a new family of constant-rate codes that can recover from a constant fraction of errors in the codeword symbols, and where any symbol of the…

Information Theory · Computer Science 2015-01-08 Brett Hemenway , Rafail Ostrovsky , Mary Wootters

The lacking polynomial is a graph polynomial introduced by Chan, Marckert, and Selig in 2013 that is closely related to the Tutte polynomial of a graph. It arose by way of a generalization of the Abelian sandpile model and is essentially…

Combinatorics · Mathematics 2024-11-06 Amal Alofi , Mark Dukes

In 2003, Fischermann et al. considered the maximum size of \textit{uniquely-dominatable} graphs, graphs whose dominating number is realized only by a unique dominating set. They conjectured a size bound and provide a general graph…

Combinatorics · Mathematics 2025-11-04 Garrison Koch , Darren Narayan

We obtain faster expander decomposition algorithms for directed graphs, matching the guarantees of Saranurak and Wang (SODA 2019) for expander decomposition on undirected graphs. Our algorithms are faster than prior work and also generalize…

Data Structures and Algorithms · Computer Science 2025-11-11 Henry Fleischmann , George Z. Li , Jason Li

Expander graphs, due to their mixing properties, are useful in many algorithms and combinatorial constructions. One can produce an expander graph with high probability by taking a random graph (e.g., the union of $d$ random bijections for a…

Combinatorics · Mathematics 2024-05-30 Geoffroy Caillat-Grenier

Inspired by a width invariant on permutations defined by Guillemot and Marx, Bonnet, Kim, Thomass\'e, and Watrigant introduced the twin-width of graphs, which is a parameter describing its structural complexity. This invariant has been…

Logic in Computer Science · Computer Science 2024-08-07 Édouard Bonnet , Jaroslav Nešetřil , Patrice Ossona de Mendez , Sebastian Siebertz , Stéphan Thomassé

A graph $G$ is called $C_{2k+1}$-free if it does not contain any cycle of length $2k+1$. In 1981, Haggkvist, Faudree and Schelp showed that every $n$-vertex triangle-free graph with more than $\frac{(n-1)^2}{4}+1$ edges is bipartite. In…

Combinatorics · Mathematics 2023-07-18 Sijie Ren , Jian Wang , Shipeng Wang , Weihua Yang

We determine the colored patterns that appear in any $2$-edge coloring of $K_{n,n}$, with $n$ large enough and with sufficient edges in each color. We prove the existence of a positive integer $z_2$ such that any $2$-edge coloring of…

Combinatorics · Mathematics 2024-07-15 Adriana Hansberg , Denae Ventura

Bipartite incidence graph sampling provides a unified representation of many sampling situations for the purpose of estimation, including the existing unconventional sampling methods, such as indirect, network or adaptive cluster sampling,…

Statistics Theory · Mathematics 2020-04-10 Martina Patone , Li-Chun Zhang

The 2-block intersection graph (2-BIG) of a twofold triple system (TTS) is the graph whose vertex set is composed of the blocks of the TTS and two vertices are joined by an edge if the corresponding blocks intersect in exactly two elements.…

Combinatorics · Mathematics 2020-12-29 Rosalind A. Cameron , David A. Pike

An $(a,b)$-biregular bipartite graph is a bipartite graph with bipartition $(X, Y)$ such that each vertex in $X$ has degree $a$ and each vertex in $Y$ has degree $b$. By the bipartite expander mixing lemma, biregular bipartite graphs have…

Combinatorics · Mathematics 2024-04-11 Dandan Fan , Xiaofeng Gu , Huiqiu Lin

Let red and blue points be distributed on $\mathbb{R}$ according to two independent Poisson processes $\mathcal{R}$ and $\mathcal{B}$ and let each red (blue) point independently be equipped with a random number of half-edges according to a…

Probability · Mathematics 2012-02-07 Maria Deijfen , Fabio Lopes

We show that every graph with twin-width $t$ has chromatic number $O(\omega ^{k_t})$ for some integer $k_t$, where $\omega$ denotes the clique number. This extends a quasi-polynomial bound from Pilipczuk and Soko{\l}owski and generalizes a…

Discrete Mathematics · Computer Science 2025-01-20 Romain Bourneuf , Stéphan Thomassé

In this paper, we deal with the signed bad number and the negative decision number of graphs. We show that two upper bounds concerning these two parameters for bipartite graphs in papers [Discrete Math. Algorithms Appl. 1 (2011), 33--41]…

Combinatorics · Mathematics 2021-02-02 Doost Ali Mojdeh , Babak Samadi

A matching in a bipartite graph with parts X and Y is called envy-free if no unmatched vertex in X is a adjacent to a matched vertex in Y. Every perfect matching is envy-free, but envy-free matchings exist even when perfect matchings do…

Data Structures and Algorithms · Computer Science 2022-04-15 Elad Aigner-Horev , Erel Segal-Halevi

We show that every $K_4$-free graph on $n$ vertices can be made balanced bipartite by removing at most $\frac{n^2}{9}$ edges. This proves a conjecture of Balogh, Clemen, and Lidick\'{y}, and generalizes both Sudakov's result on the…

Combinatorics · Mathematics 2026-05-08 József Balogh , Ignacy Buczek , Andrzej Grzesik , Piotr Kuc

For a given graph $F$, the $F$-saturation number of a graph $G$, denoted by $ {sat}(G, F)$, is the minimum number of edges in an edge-maximal $F$-free subgraph of $G$. In 2017, Kor\'andi and Sudakov determined $ {sat}({G}(n, p), K_r)$…

Combinatorics · Mathematics 2023-04-18 Meysam Miralaei , Ali Mohammadian , Behruz Tayfeh-Rezaie , Maksim Zhukovskii

We consider the algorithmic problem of finding large \textit{balanced} independent sets in sparse random bipartite graphs, and more generally the problem of finding independent sets with specified proportions of vertices on each side of the…

Data Structures and Algorithms · Computer Science 2023-07-27 Will Perkins , Yuzhou Wang