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A graph G is well-covered if all its maximal independent sets are of the same cardinality. Assume that a weight function w is defined on its vertices. Then G is w-well-covered if all maximal independent sets are of the same weight. For…

Discrete Mathematics · Computer Science 2013-12-31 Vadim E. Levit , David Tankus

For a directed graph $G$, and a linear order $\ll$ on the vertices of $G$, we define backedge graph $G^\ll$ to be the undirected graph on the same vertex set with edge $\{u,w\}$ in $G^\ll$ if and only if $(u,w)$ is an arc in $G$ and $w \ll…

Computational Complexity · Computer Science 2026-02-13 Grzegorz Gutowski , Mikołaj Rams

For a graph $G$ and a non-negative integral weight function $w$ on the vertex set of $G$, a set $S$ of vertices of $G$ is $w$-safe if $w(C)\geq w(D)$ for every component $C$ of the subgraph of $G$ induced by $S$ and every component $D$ of…

Combinatorics · Mathematics 2017-12-05 Stefan Ehard , Dieter Rautenbach

For a simple graph $G=(V,E)$, a \emph{proper total weighting} is a mapping $w: V\cup E\rightarrow \mathbb R$ such that for every edge $uv\in E$, $w(u)+\sum_{e\ni u}w(e)\neq w(v)+\sum_{e\ni v}w(e)$. The graph $G$ is said…

Combinatorics · Mathematics 2025-10-28 Kecai Deng , Hongyuan Qiu

A mixed dominating set of a graph $G = (V, E)$ is a mixed set $D$ of vertices and edges, such that for every edge or vertex, if it is not in $D$, then it is adjacent or incident to at least one vertex or edge in $D$. The mixed domination…

Data Structures and Algorithms · Computer Science 2019-06-27 Mingyu Xiao

Spectral characterizations of graphs is an important topic in spectral graph theory which has been studied extensively by researchers in recent years. The study of oriented graphs, however, has received less attention so far. In Qiu et…

Combinatorics · Mathematics 2024-10-15 Yiquan Chao , Wei Wang , Hao Zhang

A graph $G$ is well-covered if all its maximal independent sets are of the same cardinality. Assume that a weight function $w$ is defined on its vertices. Then $G$ is $w$-well-covered if all maximal independent sets are of the same weight.…

Discrete Mathematics · Computer Science 2018-11-13 Vadim E. Levit , David Tankus

An $(f,g)$-semi-matching in a bipartite graph $G=(U \cup V,E)$ is a set of edges $M \subseteq E$ such that each vertex $u\in U$ is incident with at most $f(u)$ edges of $M$, and each vertex $v\in V$ is incident with at most $g(v)$ edges of…

Data Structures and Algorithms · Computer Science 2018-03-28 Ján Katrenic , Gabriel Semanisin

A graph $G=(V,E)$ is representable if there exists a word $W$ over the alphabet $V$ such that letters $x$ and $y$ alternate in $W$ if and only if $(x,y)\in E$ for each $x\neq y$. If $W$ is $k$-uniform (each letter of $W$ occurs exactly $k$…

Combinatorics · Mathematics 2008-10-03 Magnus Mar Halldorsson , Sergey Kitaev , Artem Pyatkin

Let $G$ be an undirected graph. An edge of $G$ dominates itself and all edges adjacent to it. A subset $E'$ of edges of $G$ is an edge dominating set of $G$, if every edge of the graph is dominated by some edge of $E'$. We say that $E'$ is…

Discrete Mathematics · Computer Science 2017-05-24 Min Chih Lin , Vadim Lozin , Veronica A. Moyano , Jayme L. Szwarcfiter

A perfect Italian dominating function of a graph $G=(V,E)$ is a function $f : V \to \{0,1,2\}$ such that for every vertex $f(v) = 0$, it holds that $\sum_{u \in N(v)} f(u) = 2$, i.e., the weight of the labels assigned by $f$ to the…

Discrete Mathematics · Computer Science 2020-05-29 Juho Lauri , Christodoulos Mitillos

Assignment of one of the two possible directions to every edge of an undirected graph $G=(V,E)$ is called an orientation of $G$. The resulting directed graph is denoted by $\overrightarrow{G}$. A strong orientation is one in which every…

Discrete Mathematics · Computer Science 2022-03-29 K. S. Ajish Kumar , Birenjith Sasidharan , K. S. Sudeep

Let $D$ be an oriented graph. The inversion of a set $X$ of vertices in $D$ consists in reversing the direction of all arcs with both ends in $X$. The inversion number of $D$, denoted by ${\rm inv}(D)$, is the minimum number of inversions…

Combinatorics · Mathematics 2024-02-14 Jørgen Bang-Jensen , Jonas Costa Ferreira da Silva , Frédéric Havet

Consider a planar graph $G=(V,E)$ with polynomially bounded edge weight function $w:E\to [0, poly(n)]$. The main results of this paper are NC algorithms for the following problems: - minimum weight perfect matching in $G$, - maximum…

Data Structures and Algorithms · Computer Science 2018-04-20 Piotr Sankowski

A graph $G$ is $(k,k')$-choosable if the following holds: For any list assignment $L$ which assigns to each vertex $v$ a set $L(v)$ of $k$ real numbers, and assigns to each edge $e$ a set $L(e)$ of $k'$ real numbers, there is a total…

Combinatorics · Mathematics 2015-10-06 Tsai-Lien Wong , Xuding Zhu

A connected undirected graph $G = (V,E)$ is lower conformally rigid if uniform edge weights maximize the second smallest Laplacian eigenvalue $\lambda_2(w)$ over all normalized edge weights $w$, and upper conformally rigid if uniform edge…

Combinatorics · Mathematics 2026-05-15 Andrew Niu

A (fully) dynamic graph algorithm is a data structure that supports edge insertions, edge deletions, and answers certain queries that are specific to the problem under consideration. There has been a lot of research on dynamic algorithms…

Data Structures and Algorithms · Computer Science 2023-01-19 Jannick Borowitz , Ernestine Großmann , Christian Schulz

A graph G is well-covered if all its maximal independent sets are of the same cardinality. Assume that a weight function w is defined on its vertices. Then G is w-well-covered if all maximal independent sets are of the same weight. For…

Discrete Mathematics · Computer Science 2012-10-26 Vadim Levit , David Tankus

A simple graph $G=(V,E)$ is word-representable if there exists a word $w$ over the alphabet $V$ such that letters $x$ and $y$ alternate in $w$ iff $xy\in E$. Word-representable graphs generalize several important classes of graphs. A graph…

Combinatorics · Mathematics 2019-10-03 Özgür Akgün , Ian P. Gent , Sergey Kitaev , Hans Zantema

Let $G=(V, E)$ be a given edge-weighted graph and let its {\em realization} $\mathcal{G}$ be a random subgraph of $G$ that includes each edge $e \in E$ independently with probability $p$. In the {\em stochastic matching} problem, the goal…

Data Structures and Algorithms · Computer Science 2020-04-21 Soheil Behnezhad , Mahsa Derakhshan