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The graph reconstruction conjecture asserts that every simple graph on at least three vertices is uniquely determined by its deck of vertex-deleted subgraphs. In this expository article we survey the conjecture and present an…

Combinatorics · Mathematics 2026-04-21 Emilie Dufresne , Gabriela Jeronimo , Jenny Kenkel , Haydee Lindo , Nelly Villamizar

One of the most famous conjecture in graph theory is Hedetniemi's conjecture stating that the chromatic number of the categorical product of graphs is the minimum of their chromatic numbers. Using a suitable extension of the definition of…

Combinatorics · Mathematics 2014-10-14 Hossein Hajiabolhassan , Frédéric Meunier

Let $\hom(H,G)$ denote the number of homomorphisms from a graph $H$ to a graph $G$. Sidorenko's conjecture asserts that for any bipartite graph $H$, and a graph $G$ we have $$\hom(H,G)\geq…

Combinatorics · Mathematics 2017-02-03 Péter Csikvári , Zhicong Lin

In this paper, we introduce the zero divisor graph of a multiplicative lattice. We provide a counter example to Beck's conjecture for multiplicative lattices. Further, we prove that Beck's conjecture is true for reduced multiplicative…

Commutative Algebra · Mathematics 2013-10-18 Vinayak Joshi , Sachin Sarode

We prove that if $G$ is a $2r$-regular edge graceful $(p,q)$ graph with $(r,kp)=1$ then $kG$ is edge graceful for odd $k$. We also prove that for certain specific classes of $2r$-regular edge graceful graphs it is possible to drop the…

Combinatorics · Mathematics 2007-05-23 Adrian Riskin , Georgia Weidman

A well-known conjecture of Stanley is that the h-vector of a matroid is a pure O-sequence. There have been numerous papers with partial progress on this conjecture, but it is still wide open. In particular, for graphic matroids coming from…

Combinatorics · Mathematics 2021-09-06 Jacob David , Pierce Lai , SuHo Oh , Christopher Wu

Kim, K\"uhn, Osthus and Tyomkyn (Trans. Amer. Math. Soc. 371 (2019), 4655--4742) greatly extended the well-known blow-up lemma of Koml\'os, S\'ark\"ozy and Szemer\'edi by proving a `blow-up lemma for approximate decompositions' which states…

Combinatorics · Mathematics 2020-01-13 Stefan Ehard , Felix Joos

We show that the class of groups satisfying the K- and L-theoretic Farrell-Jones conjecture is closed under taking graph products of groups.

Group Theory · Mathematics 2014-10-01 Giovanni Gandini , Henrik Rueping

A \emph{$k$--bisection} of a bridgeless cubic graph $G$ is a $2$--colouring of its vertex set such that the colour classes have the same cardinality and all connected components in the two subgraphs induced by the colour classes have order…

Combinatorics · Mathematics 2017-07-17 M. Abreu , J. Goedgebeur , D. Labbate , G. Mazzuoccolo

An acyclic edge coloring of a graph $G$ is a proper edge coloring such that no bichromatic cycles are produced. The acyclic edge coloring conjecture by Fiam{\v{c}}ik (1978) and Alon, Sudakov and Zaks (2001) states that every simple graph…

Discrete Mathematics · Computer Science 2020-05-14 Qiaojun Shu , Guohui Lin , Eiji Miyano

Consider a graph $G$ with chromatic number $k$ and a collection of complete bipartite graphs, or bicliques, that cover the edges of $G$. We prove the following two results: \medskip \noindent $\bullet$ If the bicliques partition the edges…

Combinatorics · Mathematics 2009-03-19 Dhruv Mubayi , Sundar Vishwanathan

It was conjectured by Hoffmann-Ostenhof that the edge set of every connected cubic graph can be decomposed into a spanning tree, a matching and a family of cycles. In this paper, we show that this conjecture holds for traceable cubic…

Combinatorics · Mathematics 2016-07-19 F. Abdolhosseini , S. Akbari , H. Hashemi , M. S. Moradian

Canonical orderings and their relatives such as st-numberings have been used as a key tool in algorithmic graph theory for the last decades. Recently, a unifying concept behind all these orders has been shown: they can be described by a…

Discrete Mathematics · Computer Science 2016-07-18 Lena Schlipf , Jens M. Schmidt

The K{\L}R conjecture of Kohayakawa, {\L}uczak, and R\"odl is a statement that allows one to prove that asymptotically almost surely all subgraphs of the random graph G_{n,p}, for sufficiently large p : = p(n), satisfy an embedding lemma…

Combinatorics · Mathematics 2016-02-22 D. Conlon , W. T. Gowers , W. Samotij , M. Schacht

Let \mathcal{F}_k denote the family of 2-edge-colored complete graphs on 2k vertices in which one color forms either a clique of order k or two disjoint cliques of order k. Bollob\'as conjectured that for every \epsilon>0 and positive…

Combinatorics · Mathematics 2008-04-06 Jacob Fox , Benny Sudakov

It is conjectured by Godsil that the relative number of controllable graphs compared to the total number of simple graphs on n vertices approaches one as n tends to infinity. We prove that this conjecture is true. More generally, our…

Optimization and Control · Mathematics 2016-06-14 Sean O'Rourke , Behrouz Touri

In [{Structural properties and decomposition of linear balanced matrices}, {\it Mathematical Programming}, 55:129--168, 1992], Conforti and Rao conjectured that every balanced bipartite graph contains an edge that is not the unique chord of…

Loebl, Koml\'os, and S\'os conjectured that any graph with at least half of its vertices of degree at least k contains every tree with at most k edges. We propose a version of this conjecture for skewed trees, i.e., we consider the class of…

Combinatorics · Mathematics 2018-02-05 Tereza Klimošová , Diana Piguet , Václav Rozhoň

We show that if a graph is k-edge-connected, and we adjoin to it another graph satisfying a "contracted diameter less or equal to 2" condition, with minimal degree greater or equal to k, and some natural hypothesis on the edges connecting…

General Mathematics · Mathematics 2008-12-18 José Ignacio Alvarez-Hamelin , Jorge Rodolfo Busch

The walk matrix of an $n$-vertex graph $G$ with adjacency matrix $A$, denoted by $W(G)$, is $[e,Ae,\ldots,A^{n-1}e]$, where $e$ is the all-ones vector. Let $G\circ P_m$ be the rooted product of $G$ and a rooted path $P_m$ (taking an…

Combinatorics · Mathematics 2024-10-04 Wei Wang , Zhidan Yan , Lihuan Mao