Results 1 to 10 of about 3,509 (176)

Vertex Colorings without Rainbow Subgraphs

open access: yesDiscussiones Mathematicae Graph Theory, 2016
Given a coloring of the vertices of a graph G, we say a subgraph is rainbow if its vertices receive distinct colors. For a graph F, we define the F-upper chromatic number of G as the maximum number of colors that can be used to color the vertices of G ...
Goddard Wayne, Xu Honghai
doaj   +1 more source

A Note on the Fair Domination Number in Outerplanar Graphs

open access: yesDiscussiones Mathematicae Graph Theory, 2020
For k ≥ 1, a k-fair dominating set (or just kFD-set), in a graph G is a dominating set S such that |N(v) ∩ S| = k for every vertex v ∈ V − S. The k-fair domination number of G, denoted by fdk(G), is the minimum cardinality of a kFD-set. A fair dominating
Hajian Majid, Rad Nader Jafari
doaj   +1 more source

Vertex-Coloring with Star-Defects

open access: yes, 2016
Defective coloring is a variant of traditional vertex-coloring, according to which adjacent vertices are allowed to have the same color, as long as the monochromatic components induced by the corresponding edges have a certain structure.
A Edelman   +19 more
core   +1 more source

Recognizing Trees From Incomplete Decks

open access: yesJournal of Graph Theory, Volume 110, Issue 3, Page 322-336, November 2025.
ABSTRACT Given a graph G, the unlabeled subgraphs G − v are called the cards of G. The deck of G is the multiset { G − v : v ∈ V ( G ) }. Wendy Myrvold showed that a disconnected graph and a connected graph both on n vertices have at most ⌊ n 2 ⌋ + 1 cards in common and found (infinite) families of trees and disconnected forests for which this upper ...
Gabriëlle Zwaneveld
wiley   +1 more source

Nilpotent graphs with crosscap at most two

open access: yesAKCE International Journal of Graphs and Combinatorics, 2018
Let R be a commutative ring with identity. The nilpotent graph of R, denoted by Γ N ( R ) , is a graph with vertex set Z N ( R ) ∗ , and two vertices x and y are adjacent if and only if x y is nilpotent, where Z N ( R ) = { x ∈ R : x y is nilpotent, for ...
A. Mallika, R. Kala
doaj   +1 more source

Frequent Subgraph Mining in Outerplanar Graphs [PDF]

open access: yes, 2010
In recent years there has been an increased interest in frequent pattern discovery in large databases of graph structured objects. While the frequent connected subgraph mining problem for tree datasets can be solved in incremental polynomial time, it ...
Horvath, Tamas   +2 more
core   +1 more source

Crossing Minimization for 1-page and 2-page Drawings of Graphs with Bounded Treewidth

open access: yes, 2014
We investigate crossing minimization for 1-page and 2-page book drawings. We show that computing the 1-page crossing number is fixed-parameter tractable with respect to the number of crossings, that testing 2-page planarity is fixed-parameter tractable ...
Bannister, Michael J., Eppstein, David
core   +1 more source

On Endomorphism Universality of Sparse Graph Classes

open access: yesJournal of Graph Theory, Volume 110, Issue 2, Page 223-244, October 2025.
ABSTRACT We show that every commutative idempotent monoid (a.k.a. lattice) is the endomorphism monoid of a subcubic graph. This solves a problem of Babai and Pultr and the degree bound is best‐possible. On the other hand, we show that no class excluding a minor can have all commutative idempotent monoids among its endomorphism monoids. As a by‐product,
Kolja Knauer, Gil Puig i Surroca
wiley   +1 more source

On Vertices Enforcing a Hamiltonian Cycle

open access: yesDiscussiones Mathematicae Graph Theory, 2013
A nonempty vertex set X ⊆ V (G) of a hamiltonian graph G is called an H-force set of G if every X-cycle of G (i.e. a cycle of G containing all vertices of X) is hamiltonian.
Fabrici Igor   +2 more
doaj   +1 more source

Pixel and Voxel Representations of Graphs

open access: yes, 2015
We study contact representations for graphs, which we call pixel representations in 2D and voxel representations in 3D. Our representations are based on the unit square grid whose cells we call pixels in 2D and voxels in 3D.
A Bezdek   +31 more
core   +1 more source

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