Results 91 to 100 of about 332 (184)

On Hereditary Helly classes of graphs

Discrete Mathematics & Theoretical Computer Science, 2008
In graph theory, the Helly property has been applied to families of sets, such as cliques, disks, bicliques, and neighbourhoods, leading to the classes of clique-Helly, disk-Helly, biclique-Helly, neighbourhood-Helly graphs, respectively.
Marina Groshaus, Jayme Luiz Szwarcfiter
doaj  

Certifying Induced Subgraphs in Large Graphs

Journal of Graph Algorithms and Applications
We introduce I/O-efficient certifying algorithms for the recognition of bipartite, split, threshold, bipartite chain, and trivially perfect graphs. When the input graph is a member of the respective class, the certifying algorithm returns a certificate
Ulrich Meyer, Hung Tran, Konstantinos Tsakalidis   +2 more
doaj   +1 more source

The spectral Turán problem about graphs of given size with forbidden subgraphs

AKCE International Journal of Graphs and Combinatorics
Let G be a graph of size m and [Formula: see text] be the spectral radius of its adjacency matrix. A graph is said to be H-free if it does not contain a subgraph isomorphic to H. Let [Formula: see text] be the graph obtained by adding a pendent vertex to
Amir Rehman, S. Pirzada
doaj   +1 more source

Small clique number graphs with three trivial critical ideals

Special Matrices, 2018
The critical ideals of a graph are the determinantal ideals of the generalized Laplacian matrix associated to a graph. Previously, they have been used in the understanding and characterizing of the graphs with critical group with few invariant factors ...
Alfaro Carlos A., Valencia Carlos E.
doaj   +1 more source

$2$-polarity and algorithmic aspects of polarity variants on cograph superclasses [PDF]

Discrete Mathematics & Theoretical Computer Science
A graph $G$ is said to be an $(s, k)$-polar graph if its vertex set admits a partition $(A, B)$ such that $A$ and $B$ induce, respectively, a complete $s$-partite graph and the disjoint union of at most $k$ complete graphs.
Fernando Esteban Contreras-Mendoza, César Hernández-Cruz   +1 more
doaj   +1 more source

Path Eccentricity and Forbidden Induced Subgraphs

CoRR
Abstract.
Cichacz, Sylwia, Hilaire, Claire, Masařík, Tomáš, Masaříková, Jana, Milanič, Martin   +4 more
openaire   +3 more sources

On the Caccetta-Haggkvist conjecture with forbidden subgraphs

J. Graph Theory, 2011
The Caccetta-Haggkvist conjecture made in 1978 asserts that every orgraph on n vertices without oriented cycles of length <= l must contain a vertex of outdegree at most (n-1)/l. It has a rather elaborate set of (conjectured) extremal configurations. In this paper we consider the case l=3 that received quite a significant attention in the literature.
openaire   +4 more sources

Relative timing information and orthology in evolutionary scenarios. [PDF]

Algorithms Mol Biol, 2023
Schaller D, Hartmann T, Lafond M, Stadler PF, Wieseke N, Hellmuth M.   +5 more
europepmc   +1 more source

On Universal Graphs With Forbidden Topological Subgraphs

European Journal of Combinatorics, 1985
A graph \(G^*\) is called universal in a class \(\bar G\) of countable graphs if it contains a copy of every G in \(\bar G.\) The graph \(G^*\) is called strongly universal if every G in \(\bar G\) is isomorphic to an induced subgraph of \(G^*\). For each pair n and m of positive integers, let \(\bar G(\)n,m) represent the class of all countable graphs
openaire   +3 more sources

On the validity of Lovász’s inequality for induced star-perfect graphs

Journal of Inequalities and Applications
Let F $\mathcal{F}$ be a family of graphs. For a graph G, define θ F ( G ) $\theta _{F}(G)$ as the minimum number of induced subgraphs of G, each isomorphic to a member of F $\mathcal{F}$ , needed to cover V ( G ) $V(G)$ , and α F ( G ) $\alpha _{F}(G ...
James Alex, Louis Caccetta
doaj   +1 more source