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For a finite graph $G$, we study the maximum $2$-edge colorable subgraph problem and a related ratio $\frac{\mu(G)}{\nu(G)}$, where $\nu(G)$ is the matching number of $G$, and $\mu(G)$ is the size of the largest matching in any pair…

Combinatorics · Mathematics 2023-06-07 Huizheng , Guo , Kieran Kaempen , Zhengda Mo , Sam Qunell , Joe Rogge , Chao Song , Anush Tserunyan , Jenna Zomback

An edge labeling of a connected graph $G = (V, E)$ is said to be local antimagic if it is a bijection $f:E \to\{1,\ldots ,|E|\}$ such that for any pair of adjacent vertices $x$ and $y$, $f^+(x)\not= f^+(y)$, where the induced vertex label…

Combinatorics · Mathematics 2024-04-30 Gee-Choon Lau , Wai Chee Shiu , M. Nalliah , K. Premalatha

The spanning tree packing number of a graph $G$, denoted by $\tau(G)$, is the maximum number of edge-disjoint spanning trees contained in $G$. The study of $\tau(G)$ is one of the classic problems in graph theory. Cioab\u{a} and Wong…

Combinatorics · Mathematics 2022-07-12 Dandan Fan , Xiaofeng Gu , Huiqiu Lin

A distinguishing r-vertex-labelling (resp. r-edge-labelling) of an undirected graph G is a mapping $\lambda$ from the set of vertices (resp. the set of edges) of G to the set of labels {1,. .. , r} such that no non-trivial automorphism of G…

Discrete Mathematics · Computer Science 2020-05-18 Kahina Meslem , Eric Sopena

In 1982, Tuza conjectured that the size $\tau(G)$ of a minimum set of edges that intersects every triangle of a graph $G$ is at most twice the size $\nu(G)$ of a maximum set of edge-disjoint triangles of $G$. This conjecture was proved for…

Combinatorics · Mathematics 2024-05-21 Luis Chahua , Juan Gutierrez

The detour order of a graph $G$, denoted $\tau(G)$, is the order of a longest path in $G$. A partition $(A, B)$ of $V(G)$ such that $\tau(\langle A \rangle) \leq a$ and $\tau(\langle B \rangle) \leq b$ is called an $(a, b)$-partition of…

Combinatorics · Mathematics 2014-09-16 G. Sethuraman

In 1974, Erd\H{o}s asked the following question: given a graph $G$ and a directed graph $\vec{H}$, how many ways are there to orient the edges of $G$ such that it does not contain $\vec{H}$ as a subgraph? We denote this value by $D(G,…

Combinatorics · Mathematics 2025-04-04 Hannah Sheats

A collection of graphs is \textit{nearly disjoint} if every pair of them intersects in at most one vertex. We prove that if $G_1, \dots, G_m$ are nearly disjoint graphs of maximum degree at most $D$, then the following holds. For every…

Combinatorics · Mathematics 2023-10-31 Tom Kelly , Daniela Kühn , Deryk Osthus

An edge labeling of a connected graph $G = (V, E)$ is said to be local antimagic if it is a bijection $f:E \to\{1,\ldots ,|E|\}$ such that for any pair of adjacent vertices $x$ and $y$, $f^+(x)\not= f^+(y)$, where the induced vertex label…

Combinatorics · Mathematics 2022-10-11 Gee-Choon Lau , Wai-Chee Shiu , Ruixue Zhang , K. Premalatha , M. Nalliah

The Wiener index of a strong digraph $D$ is defined as the sum of the distances between all ordered pairs of vertices. This definition has been extended to digraphs that are not necessarily strong by defining the distance from a vertex $a$…

Combinatorics · Mathematics 2022-09-20 Peter Dankelmann

We give an affirmative answer to a long-standing conjecture of Thomassen, stating that every sufficiently highly connected graph has a $k$-vertex-connected orientation. We prove that a connectivity of order $O(k^2)$ suffices. As a key tool,…

Combinatorics · Mathematics 2025-03-12 Dániel Garamvölgyi , Tibor Jordán , Csaba Király , Soma Villányi

Let $G = (V,E)$ be a connected simple graph. A bijection $f: E \rightarrow \{1,2,\ldots,|E|\}$ is called a local antimagic labeling of $G$ if $f^+(u) \neq f^+(v)$ holds for any two adjacent vertices $u$ and $v$, where $f^+(u) = \sum_{e\in…

Combinatorics · Mathematics 2022-09-01 Gee-Choon Lau , Wai-Chee Shiu , K. Premalatha , Ruixue Zhang , M. Nalliah

Let $G$ be a connected nonregular graphs of order $n$ with maximum degree $\Delta$ that attains the maximum spectral radius. Liu and Li (2008) proposed a conjecture stating that $G$ has a degree sequence $(\Delta,\ldots,\Delta,\delta)$ with…

Combinatorics · Mathematics 2024-11-27 Zejun Huang , Jiahui Liu , Chenxi Yang

A graph $G$ is said to be super edge-magic if there exists a bijective function $f:V\left(G\right) \cup E\left(G\right)\rightarrow \left\{1, 2, \ldots , \left\vert V\left( G\right) \right\vert +\left\vert E\left( G\right) \right\vert…

Combinatorics · Mathematics 2023-08-22 Rikio Ichishima , Francesc A. Muntaner-Batle

An edge labeling of a connected graph $G = (V, E)$ is said to be local antimagic if there is a bijection $f:E \to\{1,\ldots ,|E|\}$ such that for any pair of adjacent vertices $x$ and $y$, $f^+(x)\not= f^+(y)$, where the induced vertex…

Combinatorics · Mathematics 2024-03-26 Gee-Choon Lau , Wai Chee Shiu , K. Premalatha , M. Nalliah

A bisection of a graph is a bipartition of its vertex set in which the number of vertices in the two parts differ by at most 1, and its size is the number of edges which go across the two parts. In this paper, motivated by several questions…

Combinatorics · Mathematics 2013-05-29 Choongbum Lee , Po-Shen Loh , Benny Sudakov

A graph $G=(V,E)$ is said to be distance magic if there is a bijection $f$ from a vertex set of $G$ to the first $|V(G)|$ natural numbers such that for each vertex $v$, its weight given by $\sum_{u \in N(v)}f(u)$ is constant, where $N(v)$…

Combinatorics · Mathematics 2024-02-09 Himadri Mukherjee , Ravindra Pawar , Tarkeshwar Singh

Let $D$ be a connected oriented graph. A set $S \subseteq V(D)$ is convex in $D$ if, for every pair of vertices $x, y \in S$, the vertex set of every $xy$-geodesic, ($xy$ shortest directed path) and every $yx$-geodesic in $D$ is contained…

A good edge-labeling of a graph [Ara\'ujo, Cohen, Giroire, Havet, Discrete Appl. Math., forthcoming] is an assignment of numbers to the edges such that for no pair of vertices, there exist two non-decreasing paths. In this paper, we study…

Combinatorics · Mathematics 2012-07-30 Michel Bode , Babak Farzad , Dirk Oliver Theis

This paper is dedicated to studying the following question: Is it always possible to injectively assign the weights $1,...,|E(G)|$ to the edges of any given graph $G$ (with no component isomorphic to $K_2$) so that every two adjacent…

Combinatorics · Mathematics 2017-04-06 Julien Bensmail , Mohammed Senhaji , Kasper Szabo Lyngsie
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