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We recall several known results about minimally 2-connected graphs, and show that they all follow from a decomposition theorem. Starting from an analogy with critically 2-connected graphs, we give structural characterizations of the classes…

Discrete Mathematics · Computer Science 2016-03-27 Pierre Aboulker , Marko Radovanović , Nicolas Trotignon , Kristina Vušković

A proper edge coloring of a graph $G$ with colors $1,2,\dots,t$ is called a \emph{cyclic interval $t$-coloring} if for each vertex $v$ of $G$ the edges incident to $v$ are colored by consecutive colors, under the condition that color $1$ is…

Combinatorics · Mathematics 2017-03-30 Armen S. Asratian , Carl Johan Casselgren , Petros A. Petrosyan

Truemper configurations are four types of graphs (namely thetas, wheels, prisms and pyramids) that play an important role in the proof of several decomposition theorems for hereditary graph classes. In this paper, we prove two structure…

Combinatorics · Mathematics 2023-10-23 Emilie Diot , Marko Radovanović , Nicolas Trotignon , Kristina Vušković

A vertex with neighbours of degrees $d_1 \geq ... \geq d_r$ has {\em vertex type} $(d_1, ..., d_r)$. A graph is {\em vertex-oblique} if each vertex has a distinct vertex-type. While no graph can have distinct degrees, Schreyer, Walther and…

Combinatorics · Mathematics 2007-05-23 Alastair Farrugia

Let $G=(V(G),E(G))$ be a simple, finite and undirected graph of order $p$ and size $q$. For $k\ge 1$, a bijection $f: V(G)\cup E(G) \to \{k, k+1, k+2, \ldots, k+p+q-1\}$ such that $f(uv)= |f(u) - f(v)|$ for every edge $uv\in E(G)$ is said…

Combinatorics · Mathematics 2023-05-05 Gee-Choon Lau , Wai-Chee Shiu , Ho-Kuen Ng

A balanced graph is a bipartite graph with no induced circuit of length 2 mod 4. These graphs arise in linear programming. We focus on graph-algebraic properties of balanced graphs to prove a complete classification of balanced Cayley…

Combinatorics · Mathematics 2007-07-03 Joy Morris , Pablo Spiga , Kerri Webb

A graph is \emph{$(\mathcal{I}, \mathcal{F})$-partitionable} if its vertex set can be partitioned into two parts such that one part $\mathcal{I}$ is an independent set, and the other $\mathcal{F}$ induces a forest. A graph is…

Combinatorics · Mathematics 2025-02-27 Zhengjiao Liu , Tao Wang , Xiaojing Yang

In the present paper we give an explicit formula which allows us immediately to describe a unique Gauss circuit on a framed 4-valent graph (a graph with a structure of opposite edges) from an arbitrary Euler tour on the graph whenever the…

Combinatorics · Mathematics 2009-12-01 Denis P. Ilyutko

Odd coloring is a variant of proper coloring and has received wide attention. We study the list-coloring version of this notion in this paper. We prove that if $G$ is a graph embeddable in the torus or the Klein bottle with no cycle of…

Combinatorics · Mathematics 2025-10-14 Rishi Balaji , Victoria Khazhinsky , Chun-Hung Liu , Kevin Qin

We provide a generating function for the (graded) dimensions of M. Kontsevich's graph complexes of ordinary graphs. This generating function can be used to compute the Euler characteristic in each loop order. Furthermore, we show that…

Quantum Algebra · Mathematics 2015-02-23 Thomas Willwacher , Marko Živković

A graph $G$ is called $C_4$-free if it does not contain the cycle $C_4$ as an induced subgraph. Hubenko, Solymosi and the first author proved (answering a question of Erd\H os) a peculiar property of $C_4$-free graphs: $C_4$ graphs with $n$…

Combinatorics · Mathematics 2015-09-22 A. Gyarfas , G. N. Sarkozy

An (edge) decomposition of a graph $G$ is a set of subgraphs of $G$ whose edge sets partition the edge set of $G$. Here we show, for each odd $\ell \geq 5$, that any graph $G$ of sufficiently large order $n$ with minimum degree at least…

Combinatorics · Mathematics 2024-11-27 Darryn Bryant , Peter Dukes , Daniel Horsley , Barbara Maenhaut , Richard Montgomery

Bipartite graphs are a fundamental concept in graph theory with diverse applications. A graph is bipartite iff it contains no odd cycles, a characteristic that has many implications in diverse fields ranging from matching problems to the…

Combinatorics · Mathematics 2024-12-10 Marzieh Eidi , Sayan Mukherjee

An Eulerian circuit in a directed graph is one of the most fundamental Graph Theory notions. Detecting if a graph $G$ has a unique Eulerian circuit can be done in polynomial time via the BEST theorem by de Bruijn, van Aardenne-Ehrenfest,…

Data Structures and Algorithms · Computer Science 2023-05-26 Nidia Obscura Acosta , Alexandru I. Tomescu

A finite simple graph is called a 2-graph if all of its unit spheres S(x) are cyclic graphs of length 4 or larger. A 2-graph G is Eulerian if all vertex degrees of G are even. An edge refinement of a graph splits an edge (a,b) to two edges…

Discrete Mathematics · Computer Science 2018-08-23 Oliver Knill

A $P_\ell$-decomposition of a graph $G$ is a set of paths with $\ell$ edges in $G$ that cover the edge set of $G$. Favaron, Genest, and Kouider (2010) conjectured that every $(2k+1)$-regular graph that contains a perfect matching admits a…

Combinatorics · Mathematics 2020-12-10 Fábio Botler , Luiz Hoffmann

We introduce a new cohomology theory for planar trivalent graphs with perfect matchings. The graded Euler characteristic of the cohomology is a one variable polynomial called the 2-factor polynomial that, if nonzero when evaluated at one,…

Geometric Topology · Mathematics 2023-03-15 Scott Baldridge

A walk $W$ in edge-colored graphs is called properly colored (PC) if every pair of consecutive edges in $W$ is of different color. We introduce and study five types of PC acyclicity in edge-colored graphs such that graphs of PC acyclicity…

Discrete Mathematics · Computer Science 2016-09-13 Gregory Gutin , Mark Jones , Bin Sheng , Magnus Wahlstrom , Anders Yeo

A graph with $v$ vertices is $(r)$-pancyclic if it contains precisely $r$ cycles of every length from 3 to $v$. A bipartite graph with even number of vertices $v$ is said to be $(r)$-bipancyclic if it contains precisely $r$ cycles of each…

Combinatorics · Mathematics 2015-10-13 Abdollah Khodkar , Oliver Sawin , Lisa Mueller , WonHyuk Choi

Edge-girth-regular graphs (abbreviated as \emph{egr} graphs) are regular graphs in which every edge is contained in the same number of shortest cycles. We prove that there is no $3$-regular \emph{egr} graph with girth $7$ such that every…

Combinatorics · Mathematics 2024-04-01 Leen Droogendijk