Results 31 to 40 of about 4,527 (99)
Countable connected-homogeneous digraphs [PDF]
, 2013 A digraph is connected-homogeneous if every isomorphism between two finite connected induced subdigraphs extends to an automorphism of the whole digraph.
Hamann, Matthias
core
Priors on exchangeable directed graphs
, 2016 Directed graphs occur throughout statistical modeling of networks, and exchangeability is a natural assumption when the ordering of vertices does not matter.
Ackerman, Nathanael +2 more
core +1 more source
Strong arc decompositions of split digraphs
Journal of Graph Theory, Volume 108, Issue 1, Page 5-26, January 2025.Abstract A strong arc decomposition of a digraph D = ( V , A ) is a partition of its arc set A into two sets A 1 , A 2 such that the digraph D i = ( V , A i ) is strong for i = 1 , 2. Bang‐Jensen and Yeo conjectured that there is some K such that every K‐arc‐strong digraph has a strong arc decomposition. They also proved that with one exception on four
Jørgen Bang‐Jensen, Yun Wang
wiley +1 more source
Seymour's second neighbourhood conjecture: random graphs and reductions
Random Structures &Algorithms, Volume 66, Issue 1, January 2025.Abstract A longstanding conjecture of Seymour states that in every oriented graph there is a vertex whose second outneighbourhood is at least as large as its outneighbourhood. In this short note we show that, for any fixed p∈[0,1/2)$$ p\in \left[0,1/2\right) $$, a.a.s.
Alberto Espuny Díaz +3 more
wiley +1 more source
Local Out-Tournaments with Upset Tournament Strong Components I: Full and Equal {0,1}-Matrix Ranks [PDF]
, 2010 A digraph D is a local out-tournament if the outset of every vertex is a tournament. Here, we use local out-tournaments, whose strong components are upset tournaments, to explore the corresponding ranks of the adjacency matrices.
Derby, Jason M. +2 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
Oriented paths in n-chromatic digraphs [PDF]
, 2010 In this thesis, we try to treat the problem of oriented paths in n-chromatic digraphs. We first treat the case of antidirected paths in 5-chromatic digraphs, where we explain El-Sahili's theorem and provide an elementary and shorter proof of it.
Nasser, Rajai
core +2 more sources
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
A sufficient condition for pre-Hamiltonian cycles in bipartite digraphs
, 2017 Let $D$ be a strongly connected balanced bipartite directed graph of order $2a\geq 10$ other than a directed cycle. Let $x,y$ be distinct vertices in $D$.
Darbinyan, Samvel Kh. +1 more
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