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In recent years, there has been significant interest in characterizing the induced subgraph obstructions to bounded treewidth and pathwidth. While this has recently been resolved for pathwidth, the case of treewidth remains open, and prior…

Combinatorics · Mathematics 2025-07-31 Maria Chudnovsky , David Fischer , Sepehr Hajebi , Sophie Spirkl , Bartosz Walczak

In this note we give a combinatorial characterization of all the unmixed bipartite graphs.

Combinatorics · Mathematics 2011-04-05 Rafael H. Villarreal

It is an important fact that extremal discrete structures -- that is, discrete structures of maximal size among those that avoid certain configurations -- exhibit strong pseudorandom behavior. We present instances of this phenomenon in the…

Combinatorics · Mathematics 2026-04-14 Noé de Rancourt , Pandelis Dodos , Konstantinos Tyros

We present an elementary construction of an uncountably chromatic graph without uncountable, infinitely connected subgraphs.

Combinatorics · Mathematics 2024-05-20 Nathan Bowler , Max Pitz

Random graphs with a given degree sequence are often constructed using the configuration model, which yields a random multigraph. We may adjust this multigraph by a sequence of switchings, eventually yielding a simple graph. We show that,…

Probability · Mathematics 2019-02-01 Svante Janson

We give inductive constructions of independent graphs that contain implied nonedges but do not contain any non-trivial rigid subgraphs, or \emph{nucleations}: some of the constructions and proofs apply to 3-dimensional abstract rigidity…

Combinatorics · Mathematics 2025-08-19 Jialong Cheng , Meera Sitharam , Ileana Streinu , William Sims

Decomposable graphs are known for their tedious and complicated Markov update steps. Instead of modelling them directly, this work introduces a class of tree-dependent bipartite graphs that span the projective space of decomposable graphs.…

Methodology · Statistics 2017-10-11 Mohamad Elmasri

In this work we give precise asymptotic expressions on the probability of the existence of fixed-size components at the threshold of connectivity for random geometric graphs.

Discrete Mathematics · Computer Science 2008-07-23 J. Diaz , D. Mitsche , X. Perez

We study countable graphs that -- up to isomorphism and with probability one -- arise from a random process, in a similar fashion as the Rado graph. Unlike in the classical case, we do not require that probabilities assigned to pairs of…

Combinatorics · Mathematics 2026-01-23 Ziemowit Kostana , Jarosław Swaczyna , Agnieszka Widz

The objectives of this article are three-fold. Firstly, we present for the first time explicit constructions of an infinite family of \textit{unbalanced} Ramanujan bigraphs. Secondly, we revisit some of the known methods for constructing…

Machine Learning · Statistics 2020-11-16 Shantanu Prasad Burnwal , Kaneenika Sinha , Mathukumalli Vidyasagar

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 enumerate weighted graphs with a certain upper bound condition. We also compute the generating function of the numbers of these graphs, and prove that it is a rational function. In particular, we show that if the given graph is a…

Combinatorics · Mathematics 2007-05-23 Miklós Bóna , Hyeong-Kwan Ju , Ruriko Yoshida

Construction of non-isomorphic cospectral graphs is a nontrivial problem in spectral graph theory specially for large graphs. In this paper, we establish that graph theoretical partial transpose of a graph is a potential tool to create…

Combinatorics · Mathematics 2018-08-13 Supriyo Dutta , Bibhas Adhikari

This paper studies higher index theory for a random sequence of bounded degree, finite graphs with diameter tending to infinity. We show that in a natural model for such random sequences the following hold almost surely: the coarse…

K-Theory and Homology · Mathematics 2014-04-28 Rufus Willett

In 2007 we introduced a general model of sparse random graphs with independence between the edges. The aim of this paper is to present an extension of this model in which the edges are far from independent, and to prove several results…

Probability · Mathematics 2011-05-05 Bela Bollobas , Svante Janson , Oliver Riordan

We analyse graphs in which each vertex is assigned random coordinates in a geometric space of arbitrary dimensionality and only edges between adjacent points are present. The critical connectivity is found numerically by examining the size…

Statistical Mechanics · Physics 2009-11-07 Jesper Dall , Michael Christensen

The purpose of this article is to introduce a new iterative algorithm with properties resembling real life bipartite graphs. The algorithm enables us to generate wide range of random bigraphs, which features are determined by a set of…

Artificial Intelligence · Computer Science 2010-11-03 Szymon Chojnacki , Mieczysław Kłopotek

Let $F$ be a probability distribution with support on the non-negative integers. Four methods for generating a simple undirected graph with (approximate) degree distribution $F$ are described and compared. Two methods are based on the so…

Probability · Mathematics 2015-09-30 Tom Britton , Maria Deijfen , Anders Martin-Löf

We consider the random hypergraph on a finite vertex set by choosing each set of vertices as an hyperedge independently at random. We express the probability distributions of the (lower-)associated simplicial complex and the…

Combinatorics · Mathematics 2022-11-09 S. Ren

Each finite and connected bipartite graph induces a finite collection of non-isomorphic dessins d'enfants, that is, $2$-cell embeddings of it into some closed orientable surface. We describe an algorithm to compute all these dessins…

Combinatorics · Mathematics 2017-08-24 Ruben A. Hidalgo