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A graph is weakly $2$-colored if the nodes are labeled with colors black and white such that each black node is adjacent to at least one white node and vice versa. In this work we study the distributed computational complexity of weak…

Distributed, Parallel, and Cluster Computing · Computer Science 2019-02-19 Alkida Balliu , Juho Hirvonen , Dennis Olivetti , Jukka Suomela

A graph/multigraph $G$ is locally irregular if endvertices of every its edge possess different degrees. The locally irregular edge coloring of $G$ is its edge coloring with the property that every color induces a locally irregular…

Combinatorics · Mathematics 2024-10-04 Igor Grzelec , Tomáš Madaras , Alfréd Onderko , Roman Soták

Hoffman proved that for a simple graph $G$, the chromatic number $\chi(G)$ obeys $\chi(G) \le 1 - \frac{\lambda_1}{\lambda_{n}}$ where $\lambda_1$ and $\lambda_n$ are the maximal and minimal eigenvalues of the adjacency matrix of $G$…

Combinatorics · Mathematics 2014-12-15 Franklin H. J. Kenter

For a graph G and an integer t we let mcc_t(G) be the smallest m such that there exists a coloring of the vertices of G by t colors with no monochromatic connected subgraph having more than m vertices. Let F be any nontrivial minor-closed…

Combinatorics · Mathematics 2007-05-23 N. Linial , J. Matousek , O. Sheffet , G. Tardos

A total graph is an ordered triple $(V_0, V_1, E)$, where $V_0, V_1$ are the sets of empty and full vertices, respectively, $V_0 \cap V_1 = \emptyset$, and the set of edges $E$ is a subset of \(\binom{V_0 \cup V_1}{2}\) $(E\cap(V_0 \cup…

Given a graph $F$ and an integer $r \ge 2$, a partition $\widehat{F}$ of the edge set of $F$ into at most $r$ classes, and a graph $G$, define $c_{r, \widehat{F}}(G)$ as the number of $r$-colorings of the edges of $G$ that do not contain a…

Combinatorics · Mathematics 2016-05-30 Fabricio S. Benevides , Carlos Hoppen , Rudini Menezes Sampaio

A graph is \textit{locally irregular} if the neighbors of every vertex $v$ have degrees distinct from the degree of $v$. \textit{locally irregular edge-coloring} of a graph $G$ is an (improper) edge-coloring such that the graph induced on…

Combinatorics · Mathematics 2018-06-29 Borut Lužar , Jakub Przybyło , Roman Soták

We consider the problem of minimizing the number of monochromatic subgraphs of a random graph, when each node of the host graph is assigned one of the two colors. Using a recently discovered contiguity between appearance of strictly…

Combinatorics · Mathematics 2026-02-04 Yatin Dandi , David Gamarnik , Haodong Zhu

In this paper, we introduce a class of graphs which we call average hereditary graphs. Many graphs that occur in the usual graph theory applications belong to this class of graphs. Many popular types of graphs fall under this class, such as…

Discrete Mathematics · Computer Science 2025-08-11 Syed Mujtaba Hassan , Shahid Hussain

A simple topological graph T = (V(T), E(T)) is a drawing of a graph in the plane where every two edges have at most one common point (an endpoint or a crossing) and no three edges pass through a single crossing. Topological graphs G and H…

Combinatorics · Mathematics 2022-12-13 Jan Kynčl

In this paper uniquely list colorable graphs are studied. A graph G is called to be uniquely k-list colorable if it admits a k-list assignment from which G has a unique list coloring. The minimum k for which G is not uniquely k-list…

Combinatorics · Mathematics 2008-01-03 Ch. Eslahchi , M. Ghebleh , H. Hajiabolhassan

Combinatorics, in particular graph theory, has a rich history of being a domain of successful applications of tools from other areas of mathematics, including topological methods. Here, we survey the study of the Hom-complexes, and the ways…

Algebraic Topology · Mathematics 2007-05-23 Dmitry N. Kozlov

NP-complete problems should be hard on some instances but those may be extremely rare. On generic instances many such problems, especially related to random graphs, have been proven easy. We show the intractability of random instances of a…

Computational Complexity · Computer Science 2018-10-25 Leonid A. Levin , Ramarathnam Venkatesan

A graph is locally irregular if no two adjacent vertices have the same degree. The irregular chromatic index $\chi_{\rm irr}'(G)$ of a graph $G$ is the smallest number of locally irregular subgraphs needed to edge-decompose $G$. Not all…

Combinatorics · Mathematics 2016-04-04 Julien Bensmail , Martin Merker , Carsten Thomassen

A graph is locally irregular if the degrees of the end-vertices of every edge are distinct. An edge coloring of a graph G is locally irregular if every color induces a locally irregular subgraph of G. A colorable graph G is any graph which…

Combinatorics · Mathematics 2022-07-21 Jelena Sedlar , Riste Škrekovski

In 1973, Erd\H{o}s and Simonovits asked whether every $n$-vertex triangle-free graph with minimum degree greater than $1/3 \cdot n$ is 3-colourable. This question initiated the study of the chromatic profile of triangle-free graphs: for…

Combinatorics · Mathematics 2023-08-22 Freddie Illingworth

Color refinement is a classical technique used to show that two given graphs G and H are non-isomorphic; it is very efficient, although it does not succeed on all graphs. We call a graph G amenable to color refinement if it succeeds in…

Computational Complexity · Computer Science 2015-05-05 V. Arvind , Johannes Köbler , Gaurav Rattan , Oleg Verbitsky

A graph $H$ is called strongly common if for every coloring $\phi$ of $K_n$ with two colors, the number of monochromatic copies of $H$ is at least the number of monochromatic copies of $H$ in a random coloring of $K_n$ with the same density…

Combinatorics · Mathematics 2023-05-19 Leo Versteegen

In extremal combinatorics, it is common to focus on structures that are minimal with respect to a certain property. In particular, critical and list-critical graphs occupy a prominent place in graph coloring theory. Stiebitz, Tuza, and…

Combinatorics · Mathematics 2026-02-27 Anton Bernshteyn , Hemanshu Kaul , Jeffrey A. Mudrock , Gunjan Sharma

For studying topological obstructions to graph colorings, Hom-complexes were introduced by Lov\'{a}sz. A graph $T$ is called a test graph if for every graph $H$, the $k$-connectedness of $|Hom(T, H)|$ implies $\chi (H)\geq k + 1 + \chi(T)$.…

Combinatorics · Mathematics 2017-06-30 Hamid Reza Daneshpajouh