Results 171 to 180 of about 2,913 (200)

Saturated Partial Embeddings of Planar Graphs

open access: yesJournal of Graph Theory, EarlyView.
ABSTRACT In this work, we study how far one can deviate from optimal behavior when embedding a planar graph. For a planar graph G $G$, we say that a plane subgraph H ⊆ G $H\subseteq G$ is a plane‐saturated subgraph if adding any edge (possibly with new vertices) to H $H$ would either violate planarity or make the resulting graph no longer a subgraph of
Alexander Clifton, Nika Salia
wiley   +1 more source

A Note on Lovász Characterization of Perfect Graphs

open access: yesJournal of Graph Theory, EarlyView.
ABSTRACT A graph is perfect if, for every induced subgraph, the chromatic number equals the size of its largest clique. In 1972, Lovász established a fundamental characterization of perfect graphs, showing that a graph is perfect if and only if, for every induced subgraph, the product of the size of the largest independent set and the size of the ...
James Alex
wiley   +1 more source

Identity-by-descent segments in large samples. [PDF]

open access: yesTheor Popul Biol
Temple SD, Thompson EA.
europepmc   +1 more source

The 1 3 $\frac{1}{3}$‐Conjectures for Domination in Cubic Graphs

open access: yesJournal of Graph Theory, EarlyView.
ABSTRACT A set S $S$ of vertices in a graph G $G$ is a dominating set of G $G$ if every vertex not in S $S$ is adjacent to a vertex in S $S$. The domination number of G $G$, denoted by γ ( G ) $\gamma (G)$, is the minimum cardinality among all dominating sets in G $G$. In a breakthrough paper in 2008, Löwenstein and Rautenbach proved that if G $G$ is a
Paul Dorbec, Michael A. Henning
wiley   +1 more source

Flow‐Critical Graphs

open access: yesJournal of Graph Theory, EarlyView.
ABSTRACT Lovász et al. proved that every six‐edge‐connected graph has a nowhere‐zero three‐flow. In fact, they proved a more technical statement, which says that there exists a nowhere‐zero three‐flow that extends the flow prescribed on the incident edges of a single vertex z $z$ with bounded degree. We extend this theorem of Lovász et al.
Arnbjörg Soffía Árnadóttir   +5 more
wiley   +1 more source

From Finding a Spanning Subgraph H $H$ to an H $H$‐Factor

open access: yesJournal of Graph Theory, EarlyView.
ABSTRACT A typical Dirac‐type problem in extremal graph theory is to determine the minimum degree threshold for a graph G $G$ to have a spanning subgraph H $H$, for example, the Dirac theorem. A natural follow‐up problem is to seek an H $H$‐factor, which is a spanning set of vertex‐disjoint copies of H $H$.
Allan Lo
wiley   +1 more source

A Structural Description of Zykov and Blanche Descartes Graphs

open access: yesJournal of Graph Theory, EarlyView.
ABSTRACT Around 1950, Zykov and Blanche Descartes proposed the two first explicit constructions of triangle‐free graphs with arbitrarily large chromatic number. We define a Zykov (resp. Blanche Descartes) graph as any induced subgraph of a graph created using Zykov's construction (resp. Blanche Descartes's).
Malory Marin   +3 more
wiley   +1 more source

Home - About - Disclaimer - Privacy