Results 21 to 30 of about 105 (77)
Immersions of Directed Graphs in Tournaments
Random Structures &Algorithms, Volume 66, Issue 1, January 2025.ABSTRACT Recently, Draganić, Munhá Correia, Sudakov and Yuster (2022) showed that every tournament on (2+o(1))k2$$ \left(2+o(1)\right){k}^2 $$ vertices contains a 1‐subdivision of a transitive tournament on k$$ k $$ vertices, which is tight up to a constant factor. We prove a counterpart of their result for immersions.
António Girão, Robert Hancock
wiley +1 more source
, 2021 A $(0,1)$-labelling of a set is said to be {\em friendly} if approximately one half the elements of the set are labelled 0 and one half labelled 1. Let $g$ be a labelling of the edge set of a graph that is induced by a labelling $f$ of the vertex set. If
Santana, Manuel +5 more
core +1 more source
Classes of intersection digraphs with good algorithmic properties
Journal of Graph Theory, Volume 106, Issue 1, Page 110-148, May 2024.Abstract While intersection graphs play a central role in the algorithmic analysis of hard problems on undirected graphs, the role of intersection digraphs in algorithms is much less understood. We present several contributions towards a better understanding of the algorithmic treatment of intersection digraphs.
Lars Jaffke +2 more
wiley +1 more source
The Lights Out Game on Directed Graphs
, 2023 We study a version of the lights out game played on directed graphs. For a digraph $D$, we begin with a labeling of $V(D)$ with elements of $\mathbb{Z}_k$ for $k \ge 2$.
Dettling, T. Elise, Parker, Darren B.
core
Counting orientations of random graphs with no directed k‐cycles
Random Structures &Algorithms, Volume 64, Issue 3, Page 676-691, May 2024.Abstract For every k⩾3$$ k\geqslant 3 $$, we determine the order of growth, up to polylogarithmic factors, of the number of orientations of the binomial random graph containing no directed cycle of length k$$ k $$. This solves a conjecture of Kohayakawa, Morris and the last two authors.
Marcelo Campos +2 more
wiley +1 more source
, 2021 © 2020, János Bolyai Mathematical Society and Springer-Verlag. We prove a conjecture of Fox, Huang, and Lee that characterizes directed graphs that have constant density in all tournaments: they are disjoint unions of trees that are each constructed in a
Zhou, Yunkun, Zhao, Yufei
core +1 more source
On Seymour's and Sullivan's second neighbourhood conjectures
Journal of Graph Theory, Volume 105, Issue 3, Page 413-426, March 2024.Abstract For a vertex x $x$ of a digraph, d + ( x ) ${d}^{+}(x)$ (d − ( x ) ${d}^{-}(x)$, respectively) is the number of vertices at distance 1 from (to, respectively) x $x$ and d + + ( x ) ${d}^{++}(x)$ is the number of vertices at distance 2 from x $x$.
Jiangdong Ai +5 more
wiley +1 more source
Embedding problems in graphs and hypergraphs [PDF]
, 2011 The first part of this thesis concerns perfect matchings and their generalisations. We determine the minimum vertex degree that ensures a perfect matching in a 3-uniform hypergraph, thereby answering a question of Hàn, Person and Schacht.
Treglown, Andrew Clark
core
Completing orientations of partially oriented graphs [PDF]
, 2018 We initiate a general study of what we call orientation completion problems. For a fixed class C of oriented graphs, the orientation completion problem asks whether a given partially oriented graph P can be completed to an oriented graph in C by ...
Huang, Jing +2 more
core +1 more source
Locating Dominating Sets in local tournaments
, 2021 International audienceA dominating set in a directed graph is a set of vertices $S$ such that all the vertices that do not belong to $S$ have an in-neighbour in $S$. A locating set $S$ is a set of vertices such that all the vertices that do not belong to
Aline Parreau +7 more
core +1 more source