Results 51 to 60 of about 886,125 (210)
On edge-intersection graphs of k-bend paths in grids [PDF]
Edge-intersection graphs of paths in grids are graphs that can be represented such that vertices are paths in a grid and edges between vertices of the graph exist whenever two grid paths share a grid edge. This type of graphs is motivated by applications
Therese Biedl, Michal Stern
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Outerplanar Partitions of Planar Graphs
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Vertex Colorings without Rainbow Subgraphs
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
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A Note on the Fair Domination Number in Outerplanar Graphs
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
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Small Area Drawings of Outerplanar Graphs [PDF]
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DI BATTISTA, Giuseppe, FRATI, FABRIZIO
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Nilpotent graphs with crosscap at most two
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
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Face Sizes and the Connectivity of the Dual
ABSTRACT For each c ≥ 1, we prove tight lower bounds on face sizes that must be present to allow 1‐ or 2‐cuts in simple duals of c‐connected maps. Using these bounds, we determine the smallest genus on which a c‐connected map can have a simple dual with a 2‐cut and give lower and some upper bounds for the smallest genus on which a c‐connected map can ...
Gunnar Brinkmann +2 more
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On Vertices Enforcing a Hamiltonian Cycle
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
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Recognizing Trees From Incomplete Decks
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
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On Endomorphism Universality of Sparse Graph Classes
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
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