Results 111 to 120 of about 43,326 (227)

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

Tree-average distances on certain phylogenetic networks have their weights uniquely determined

Algorithms for Molecular Biology, 2012
A phylogenetic network N has vertices corresponding to species and arcs corresponding to direct genetic inheritance from the species at the tail to the species at the head.
Willson Stephen J
doaj   +1 more source

Tr-Span of Directed Wheel Graphs

Discussiones Mathematicae Graph Theory, 2018
In this paper, we consider T-colorings of directed graphs. In particular, we consider as a T-set the set Tr = {0, 1, 2, . . ., r−1, r+1, . . .}. Exact values and bounds of the Tr-span of directed graphs whose underlying graph is a wheel graph are ...
Besson Marc, Tesman Barry
doaj   +1 more source

Unordered Love in infinite directed graphs

International Journal of Mathematics and Mathematical Sciences, 1992
A digraph D=(V,A) has the Unordered Love Property (ULP) if any two different vertices have a unique common outneighbor. If both (V,A) and (V,A−1) have the ULP, we say that D has the SDULP.
Peter D. Johnson
doaj   +1 more source

Directed graph theory for the analysis of biological regulatory networks

Frontiers in Applied Mathematics and Statistics
Synchronous regulated biological networks are often represented as logical diagrams, where the precise interactions between elements remain obscured. Here, we introduce a novel type of excitation-inhibition graph based on Boolean logic, which we term ...
Martha Takane, Martha Takane, Saúl Bernal-González, Saúl Bernal-González, Jesús Mauro-Moreno, Jesús Mauro-Moreno, Gustavo García-López, Gustavo García-López, Francisco F. De-Miguel   +8 more
doaj   +1 more source

Normally Regular Digraphs [PDF]

The Electronic Journal of Combinatorics, 2015
A normally regular digraph with parameters $(v,k,\lambda,\mu)$ is a directed graph on $v$ vertices whose adjacency matrix $A$ satisfies the equation $AA^t=k I+\lambda (A+A^t)+\mu(J-I-A-A^t)$. This means that every vertex has out-degree $k$, a pair of non-adjacent vertices have $\mu$ common out-neighbours, a pair of vertices connected by an edge in one ...
openaire   +4 more sources

A Note on Some Generalized Closed Sets in Bitopological Spaces Associated to Digraphs

Journal of Applied Mathematics, 2012
Many investigations are undergoing of the relationship between topological spaces and graph theory. The aim of this short communication is to study the nature and properties of some generalized closed sets in the bitopological spaces associated to the ...
K. Kannan
doaj   +1 more source

Distance-two labelings of digraphs

, 2004
For positive integers $j\ge k$, an $L(j,k)$-labeling of a digraph $D$ is a function $f$ from $V(D)$ into the set of nonnegative integers such that $|f(x)-f(y)|\ge j$ if $x$ is adjacent to $y$ in $D$ and $|f(x)-f(y)|\ge k$ if $x$ is of distant two to $y ...
Chang, G. J., Chen, J. -J., Kuo, D., Liaw, S. C.   +3 more
core   +1 more source

On the Parameterized Complexity of Eulerian Strong Component Arc Deletion. [PDF]

Algorithmica
Blažej V, Jana S, Ramanujan MS, Strulo P.   +3 more
europepmc   +1 more source

Blurred magnitude homology of functional connectome for ASD diagnosis. [PDF]

Front Psychiatry
Kachura A, Chernyshev V, Kachan O, Levchenko E.   +3 more
europepmc   +1 more source