Results 71 to 80 of about 34,455 (233)
On cohomology theory of (di)graphs [PDF]
, 2014 To a digraph with a choice of certain integral basis, we construct a CW complex, whose integral singular cohomology is canonically isomorphic to the path cohomology of the digraph as introduced in \cite{GLMY}.
Huang, An, Yau, Shing-Tung
core
Orbits of rotor-router operation and stationary distribution of random walks on directed graphs
, 2015 The rotor-router model is a popular deterministic analogue of random walk. In this paper we prove that all orbits of the rotor-router operation have the same size on a strongly connected directed graph (digraph) and give a formula for the size.
Van Pham, Trung
core +1 more source
On Some Algorithmic and Structural Results on Flames
Journal of Graph Theory, Volume 110, Issue 4, Page 392-397, December 2025.ABSTRACT A directed graph F with a root node r is called a flame if for every vertex v other than r the local edge‐connectivity value λ F ( r , v ) from r to v is equal to ϱ F ( v ), the in‐degree of v. It is a classic, simple and beautiful result of Lovász [4] that every digraph D with a root node r has a spanning subgraph F that is a flame and the λ (
Dávid Szeszlér
wiley +1 more source
4-Transitive Digraphs I: The Structure of Strong 4-Transitive Digraphs
Discussiones Mathematicae Graph Theory, 2013 Let D be a digraph, V (D) and A(D) will denote the sets of vertices and arcs of D, respectively. A digraph D is transitive if for every three distinct vertices u, v,w ∈ V (D), (u, v), (v,w) ∈ A(D) implies that (u,w) ∈ A(D).
Hernández-Cruz César
doaj +1 more source
The Existence of Planar Hypotraceable Oriented Graphs [PDF]
Discrete Mathematics & Theoretical Computer Science, 2017 A digraph is \emph{traceable} if it has a path that visits every vertex. A digraph $D$ is \emph{hypotraceable} if $D$ is not traceable but $D-v$ is traceable for every vertex $v\in V(D)$.
Susan van Aardt +2 more
doaj +1 more source
Discrete Mathematics, 2001 The author studies the problem of upward embedding on the round sphere and gives a characterization of all spherical digraphs.
openaire +3 more sources
On the readability of overlap digraphs [PDF]
Discrete Applied Mathematics, 2015 This is a full version of a conference paper of the same title at the 26th Annual Symposium on Combinatorial Pattern Matching (CPM 2015)
Rayan Chikhi +4 more
openaire +8 more sources
Chordal Graphs, Even‐Hole‐Free Graphs and Sparse Obstructions to Bounded Treewidth
Journal of Graph Theory, Volume 110, Issue 3, Page 351-365, November 2025.ABSTRACT Even‐hole‐free graphs pose a central challenge in identifying hereditary classes of bounded treewidth. We investigate this matter by presenting and studying the following conjecture: for an integer t ≥ 4 and a graph H, every even‐hole‐free graph of large enough treewidth has an induced subgraph isomorphic to either K t or H, if (and only if) H
Sepehr Hajebi
wiley +1 more source
Vertices with the second neighborhood property in Eulerian digraphs [PDF]
Opuscula Mathematica, 2019 The Second Neighborhood Conjecture states that every simple digraph has a vertex whose second out-neighborhood is at least as large as its first out-neighborhood, i.e. a vertex with the Second Neighborhood Property.
Michael Cary
doaj +1 more source
A line digraph of a complete bipartite digraph
Applied Mathematics Letters, 2009 AbstractIn the context of the degree/diameter problem for directed graphs, it is known that the number of vertices of a strongly connected bipartite digraph satisfies a Moore-like bound in terms of its diameter k and the maximum outdegrees (d1,d2) of its partite sets of vertices. In this work, we define a family of dense digraphs, the diameter of which
Lin Sun +3 more
openaire +2 more sources