Results 51 to 60 of about 735 (221)

Line Graphs and Forbidden Induced Subgraphs

open access: yesJournal of Combinatorial Theory, Series B, 2001
zbMATH Open Web Interface contents unavailable due to conflicting licenses.
Lai, Hong-Jian, Šoltés, Ľubomír
openaire   +1 more source

Graphs whose Laplacian eigenvalues are almost all 1 or 2

open access: yesSpecial Matrices
We explicitly determine all connected graphs whose Laplacian matrices have at most four eigenvalues different from 1 and 2.
Mohammadian Ali, Xu Shanshan
doaj   +1 more source

An Implicit Enumeration Approach for Maximum Ratio Clique Relaxations

open access: yesNetworks, Volume 86, Issue 3, Page 241-262, October 2025.
ABSTRACT This article proposes an implicit enumeration approach to solve the maximum ratio s$$ s $$‐plex and the maximum ratio s$$ s $$‐defective clique problems. The approach is inspired by the classical Bron‐Kerbosch algorithm for enumerating all maximal cliques in a graph, which is extended to enumerating structures that are hereditary on induced ...
Yehor Blokhin   +4 more
wiley   +1 more source

Some Variations of Perfect Graphs

open access: yesDiscussiones Mathematicae Graph Theory, 2016
We consider (ψk−γk−1)-perfect graphs, i.e., graphs G for which ψk(H) = γk−1(H) for any induced subgraph H of G, where ψk and γk−1 are the k-path vertex cover number and the distance (k − 1)-domination number, respectively.
Dettlaff Magda   +3 more
doaj   +1 more source

Graph Classes Generated by Mycielskians

open access: yesDiscussiones Mathematicae Graph Theory, 2020
In this paper we use the classical notion of weak Mycielskian M′(G) of a graph G and the following sequence: M′0(G) = G, M′1(G) = M′(G), and M′n(G) = M′(M′n−1(G)), to show that if G is a complete graph of order p, then the above sequence is a generator ...
Borowiecki Mieczys law   +3 more
doaj   +1 more source

Characterising and recognising game-perfect graphs [PDF]

open access: yesDiscrete Mathematics & Theoretical Computer Science, 2019
Consider a vertex colouring game played on a simple graph with $k$ permissible colours. Two players, a maker and a breaker, take turns to colour an uncoloured vertex such that adjacent vertices receive different colours.
Dominique Andres, Edwin Lock
doaj   +1 more source

Longest cycles in vertex‐transitive and highly connected graphs

open access: yesBulletin of the London Mathematical Society, Volume 57, Issue 10, Page 2975-2990, October 2025.
Abstract We present progress on three old conjectures about longest paths and cycles in graphs. The first pair of conjectures, due to Lovász from 1969 and Thomassen from 1978, respectively, states that all connected vertex‐transitive graphs contain a Hamiltonian path, and that all sufficiently large such graphs even contain a Hamiltonian cycle.
Carla Groenland   +4 more
wiley   +1 more source

Forbidden subgraphs, stability and hamiltonicity

open access: yesDiscrete Mathematics, 1999
The authors study the stability of some classes of claw-free graphs defined in terms of forbidden subgraphs under the closure operation defined in \textit{Z. Ryjáček} [J. Comb. Theory, Ser. B 70, No.~2, 217-224 (1997; Zbl 0872.05032)]. They characterize all connected graphs \(A\) such that the class of all \(CA\)-free graphs (where \(C\) denotes the ...
Brousek, Jan   +2 more
openaire   +2 more sources

Tight bounds for intersection‐reverse sequences, edge‐ordered graphs, and applications

open access: yesJournal of the London Mathematical Society, Volume 112, Issue 4, October 2025.
Abstract In 2006, Marcus and Tardos proved that if A1,⋯,An$A^1,\dots,A^n$ are cyclic orders on some subsets of a set of n$n$ symbols such that the common elements of any two distinct orders Ai$A^i$ and Aj$A^j$ appear in reversed cyclic order in Ai$A^i$ and Aj$A^j$, then ∑i|Ai|=O(n3/2logn)$\sum _{i} |A^i|=O(n^{3/2}\log n)$.
Barnabás Janzer   +3 more
wiley   +1 more source

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