Results 161 to 170 of about 207,710 (268)

Transforming Solutions for the Oberwolfach Problem into Solutions for the Spouse‐Loving Variant

open access: yesJournal of Combinatorial Designs, EarlyView.
ABSTRACT The Oberwolfach problem OP ( F ) $\mathrm{OP}(F)$, for a 2‐factor F $F$ of K n ${K}_{n}$, asks whether there exists a 2‐factorization of K n ${K}_{n}$ (if n $n$ is odd) or K n − I ${K}_{n}-I$ (if n $n$ is even) where each 2‐factor is isomorphic to F $F$. Here, I $I$ denotes any 1‐factor of K n ${K}_{n}$. For even n $n$, the problem OP( F ) $(F)
Maruša Lekše, Mateja Šajna
wiley   +1 more source

R ( 5 , 5 ) ≤ 46 $R(5,5)\le 46$

open access: yesJournal of Graph Theory, EarlyView.
ABSTRACT We prove that the Ramsey number R ( 5 , 5 ) $R(5,5)$ is less than or equal to 46. The proof uses a combination of linear programming and checking a large number of cases by computer. All of the computational parts of the proof were independently implemented by both authors, with consistent results.
Vigleik Angeltveit, Brendan D. McKay
wiley   +1 more source

Towards Characterization of Five‐List‐Colorability of Toroidal Graphs

open access: yesJournal of Graph Theory, EarlyView.
ABSTRACT Through computer‐assisted enumeration, we list minimal obstructions for 5‐choosability of graphs on the torus with the following additional property: There exists a cyclic system of non‐contractible triangles around the torus where the consecutive triangles are at distance at most four.
Zdeněk Dvořák   +1 more
wiley   +1 more source

Disjoint Total Dominating Sets in Planar Graphs

open access: yesJournal of Graph Theory, EarlyView.
ABSTRACT The vertex set of any planar graph of minimum degree at least 3 can be colored in two colors so that every vertex has a neighbor of each color. If the graph is a planar triangulation, the coloring can be chosen such that every vertex has a neighbor of its own color and at least two neighbors of the opposite color.
Eva Rotenberg   +2 more
wiley   +1 more source

On Strongly and Robustly Critical Graphs

open access: yesJournal of Graph Theory, EarlyView.
ABSTRACT In extremal combinatorics, it is common to focus on structures that are minimal with respect to a certain property. In particular, critical and list‐critical graphs occupy a prominent place in graph coloring theory. Stiebitz, Tuza, and Voigt introduced strongly critical graphs, i.e., graphs that are k $k$‐critical yet L $L$‐colorable with ...
Anton Bernshteyn   +3 more
wiley   +1 more source

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