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We explore the well-known Jaeger's directed cycle double cover conjecture which is equivalent to the assertion that every cubic bridgeless graph has an embedding on a closed orientable surface with no dual loop. We associate each cubic…

Combinatorics · Mathematics 2013-10-22 Andrea Jiménez , Martin Loebl

The primary objective of this paper is to investigate the notions of geometric and sequential convexity within a graph-theoretic framework, with the aim of examining various structural properties and exploring the connection between these…

General Mathematics · Mathematics 2026-04-24 Angshuman R. Goswami

The pseudoforest version of the Strong Nine Dragon Tree Conjecture states that if a graph $G$ has maximum average degree $\text{mad}(G) = 2 \max_{H \subseteq G} \frac{e(G)}{v(G)}$ at most $2(k + \frac{d}{k+d+1})$, then it has a…

Combinatorics · Mathematics 2025-06-23 Sebastian Mies , Benjamin Moore , Evelyne Smith-Roberge

Let $G$ be a uniformly chosen simple (labelled) random graph with given degree sequence $\boldsymbol{d}$ and let $X,Y,L$ be edge-disjoint graphs on the same vertex set as $G$. We investigate the probability that $X \subseteq G$ and that $G…

Combinatorics · Mathematics 2025-10-29 John Larkin , Brendan D. McKay , Fang Tian

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

The incidence matrix of a graph is totally unimodular if and only if the graph is bipartite, i.e., it contains no odd cycles. We extend the characterization of total unimodularity to hypergraphs whose hyperedges of size at least four are…

Combinatorics · Mathematics 2025-08-26 Marco Caoduro , Meike Neuwohner , Joseph Paat

Given an integer $c\in \mathbb{N}$, we say a graph $G$ is $c$-pinched if $G$ does not contain an induced subgraph consisting of $c$ cycles, all going through a single common vertex and otherwise pairwise disjoint and with no edges between…

Combinatorics · Mathematics 2025-04-08 Bogdan Alecu , Maria Chudnovsky , Sepehr Hajebi , Sophie Spirkl

We demonstrate that when a graph exhibits a specific type of symmetry, it satisfies the Union Closed Conjecture(UCC). Additionally, we show that certain graph classes, such as Cylindrical Grid Graphs and Torus Grid Graphs also satisfy the…

Combinatorics · Mathematics 2024-11-12 Nived J M

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

It has been an open question whether the deletion or contraction of an edge in an intrinsically knotted graph always yields an intrinsically linked graph. We present a new intrinsically knotted graph that shows the answer to both questions…

Geometric Topology · Mathematics 2024-04-24 Thomas W. Mattman , Ramin Naimi , Andrei Pavelescu , Elena Pavelescu

We prove inequalities between the densities of various bipartite subgraphs in signed graphs and graphons. One of the main inequalities is that the density of any bipartite graph with girth r cannot exceed the density of the r-cycle. This…

Combinatorics · Mathematics 2010-04-20 László Lovász

Many conjectures and open problems in graph theory can either be reduced to cubic graphs or are directly stated for cubic graphs. Furthermore, it is known that for a lot of problems, a counterexample must be a snark, i.e. a bridgeless cubic…

Combinatorics · Mathematics 2023-09-27 Edita Máčajová , Giuseppe Mazzuoccolo , Vahan Mkrtchyan , Jean Paul Zerafa

We prove that for any positive integers $k$ and $d$, if a graph $G$ has maximum average degree at most $2k + \frac{2d}{d+k+1}$, then $G$ decomposes into $k+1$ pseudoforests $C_{1},\ldots,C_{k+1}$ such that there is an $i$ such that for…

Combinatorics · Mathematics 2020-07-07 Logan Grout , Benjamin Moore

One of the major results of [N. Robertson and P. D. Seymour. Graph minors. XIII. The disjoint paths problem. J. Combin. Theory Ser. B, 63(1):65--110, 1995], also known as the weak structure theorem, revealed the local structure of graphs…

Combinatorics · Mathematics 2011-03-01 Archontia C. Giannopoulou , Dimitrios M. Thilikos

In [W. Mader, Connectivity keeping paths in $k$-connected graphs, J. Graph Theory 65 (2010) 61-69.], Mader conjectured that for every positive integer $k$ and every finite tree $T$ with order $m$, every $k$-connected, finite graph $G$ with…

Combinatorics · Mathematics 2017-07-26 Yingzhi Tian , Jixiang Meng , Hong-Jian Lai , Liqiong Xu

In \cite{reed97}, Reed conjectures that the inequality $\chi (G) \leq \left \lceil \textstyle {1/2} (\omega (G) + \Delta (G) + 1) \right \rceil$ holds for any graph $G$. We prove this holds for a graph $G$ if $\bar{G}$ is disconnected. From…

Combinatorics · Mathematics 2007-05-23 landon rabern

An $\alpha$-thin tree $T$ of a graph $G$ is a spanning tree such that every cut of $G$ has at most an $\alpha$ proportion of its edges in $T$. The Thin Tree Conjecture proposes that there exists a function $f$ such that for any $\alpha >…

Computational Complexity · Computer Science 2026-01-01 Alice Moayyedi

The Berge-Fulkerson conjecture states that every bridgeless cubic graph can be covered with six perfect matchings such that each edge is covered exactly twice. An equivalent reformulation is that it's possible to find a 6-cycle 4-cover. In…

Combinatorics · Mathematics 2026-03-25 Nikolay Ulyanov

Given a graph $G$ and a subset $X$ of vertices of $G$ with size at least two, we denote by $N^2_G(X)$ the set of vertices of $G$ that have at least two neighbors in $X$. We say that a bipartite graph $G$ with sides $A$ and $B$ satisfies the…

Combinatorics · Mathematics 2025-04-04 Leandro Aurichi , Paulo Magalhães Júnior , Lyubomyr Zdomskyy

Sidorenko's conjecture states that for every bipartite graph $H$ on $\{1,\cdots,k\}$, $\int \prod_{(i,j)\in E(H)} h(x_i, y_j) d\mu^{|V(H)|} \ge \left( \int h(x,y) \,d\mu^2 \right)^{|E(H)|}$ holds, where $\mu$ is the Lebesgue measure on…

Combinatorics · Mathematics 2014-06-09 Jeong Han Kim , Choongbum Lee , Joonkyung Lee