Results 51 to 60 of about 653 (189)
Approximation hardness of dominating set problems in bounded degree graphs
, 2008 We study approximation hardness of the Minimum Dominating Set problem and its variants in undirected and directed graphs. Using a similar result obtained by Trevisan for Minimum Set Cover we prove the first explicit approximation lower bounds for various
Chlebikova, Janka +4 more
core +1 more source
Density Conditions for k $k$ Vertex‐Disjoint Triangles in Tripartite Graphs
Journal of Graph Theory, EarlyView.ABSTRACT Let n , k $n,k$ be positive integers such that n ≥ k $n\ge k$ and G $G$ be a tripartite graph with parts A , B , C $A,B,C$ such that ∣ A ∣ = ∣ B ∣ = ∣ C ∣ = n $| A| =| B| =| C| =n$. Denote the edge densities of G [ A , B ] , G [ A , C ] $G[A,B],G[A,C]$ and G [ B , C ] $G[B,C]$ by α , β $\alpha ,\beta $ and γ $\gamma $, respectively.
Mingyang Guo, Klas Markström
wiley +1 more source
On Almost-Regular Edge Colourings of Hypergraphs [PDF]
The Electronic Journal of Combinatorics, 2016 We prove that if ${\cal{H}}=(V({\cal{H}}),{\cal{E}}({\cal{H}}))$ is a hypergraph, $\gamma$ is an edge colouring of ${\cal{H}}$, and $S\subseteq V({\cal{H}})$ such that any permutation of $S$ is an automorphism of ${\cal{H}}$, then there exists a permutation $\pi$ of ${\cal{E}}({\cal{H}})$ such that $|\pi(E)|=|E|$ and $\pi(E)\setminus S=E\setminus S ...
openaire +3 more sources
Counting independent sets in regular hypergraphs
Journal of Combinatorial Theory, Series A, 2021 4 pages ...
József Balogh +2 more
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Chromatic Ramsey Numbers and Two‐Color Turán Densities
Journal of Graph Theory, EarlyView.ABSTRACT Given a graph G, its 2‐color Turán number ex ( 2 ) ( n , G ) is the maximum number of edges in an n‐vertex graph, such that the edges can be colored with two colors avoiding a monochromatic copy of G. Let π ( 2 ) ( G ) = lim n → ∞ ex ( 2 ) ( n , G ) / n 2 be the 2‐color Turán density of G.
Maria Axenovich, Simon Gaa, Dingyuan Liu
wiley +1 more source
Hypergraphs, Quasi-randomness, and Conditions for Regularity
Journal of Combinatorial Theory, Series A, 2002 The study of quasi-randomness is a flourishing topic on uniform hypergraphs. F. R. K. Chung and R. L. Graham (among others) investigated thoroughly quasi-random uniform hypergraphs of density 1/2, showing a series of important equivalent statements about these structures. In this investigations the notion of deviation plays a central role.
Yoshiharu Kohayakawa +2 more
openaire +2 more sources
EM-Training for Weighted Aligned Hypergraph Bimorphisms
, 2016 We define the concept of probabilistic aligned hypergraph bimorphism. Each such bimorphism consists of a probabilistic regular tree grammar, two hypergraph algebras in which the generated trees are interpreted, and a family of alignments between the two ...
Gebhardt, Kilian, +5 more
core +1 more source
A rate R=5/20 hypergraph-based woven convolutional code with free distance 120 [PDF]
, 2010 A rate R=5/20 hypergraph-based woven convolu- tional code with overall constraint length 67 and constituent con- volutional codes is presented. It is based on a 3-partite, 3-uniform, 4-regular hypergraph and contains rate R=3/4 constituent convolutional ...
Bocharova, Irina, +8 more
core +1 more source
, 2022 This thesis studies extremal problems in hypergraph theory, set theory, and graph theory. Results in this thesis can be divided into seven parts. In the first part, we study the feasible region $\Omega(\mathcal{F})$ of a hypergraph family $\mathcal{F}$,
Xizhi Liu (13012323)
core +1 more source
An Extended Formulation With Valid Inequalities for the Capacitated Steiner Arborescence Problem
Networks, EarlyView.ABSTRACT Given a directed graph, the Capacitated Steiner Arborescence Problem (CSAP) aims to determine the least‐cost connection from the root node to terminal nodes requiring a demand through Steiner nodes coming with a capacity, such that there is a unique path from the root to each terminal. This paper presents a new extended formulation of the CSAP,
Francesco Contu +3 more
wiley +1 more source