English
Related papers

Related papers: 5-choosability of graphs with crossings far apart

200 papers

We show that every graph with two crossings is 5-choosable. We also prove that every graph which can be made planar by removing one edge is 5-choosable.

Combinatorics · Mathematics 2011-05-16 Victor Campos , Frédéric Havet

A graph G is k-choosable if G can be properly colored whenever every vertex has a list of at least k available colors. Thomassen's theorem states that every planar graph is 5-choosable. We extend the result by showing that every graph with…

Combinatorics · Mathematics 2018-10-26 Zdeněk Dvořák , Bernard Lidický , Riste Škrekovski

We answer positively the question of Albertson asking whether every planar graph can be $5$-list-colored even if it contains precolored vertices, as long as they are sufficiently far apart from each other. In order to prove this claim, we…

Combinatorics · Mathematics 2016-12-16 Zdenek Dvorak , Bernard Lidicky , Bojan Mohar , Luke Postle

This paper studies the choosability of signed planar graphs. We prove that every signed planar graph is 5-choosable and that there is a signed planar graph which is not 4-choosable while the unsigned graph is 4-choosable. For each $k \in…

Combinatorics · Mathematics 2017-02-27 Ligang Jin , Yingli Kang , Eckhard Steffen

A graph is k-choosable if it can be colored whenever every vertex has a list of at least k available colors. We prove that if cycles of length at most four in a planar graph G are pairwise far apart, then G is 3-choosable. This is analogous…

Combinatorics · Mathematics 2012-05-28 Z. Dvorak

Consider two conditions on a graph: (1) each 5-cycle is not a subgraph of 5-wheel and does not share exactly one edge with 3-cycle, and (2) each 5-cycle is not adjacent to two 3-cycles and is not adjacent to a 4-cycle with chord. We show…

Combinatorics · Mathematics 2017-06-19 Pongpat Sittitrai , Kittikorn Nakprasit

Thomassen proved that any plane graph of girth 5 is list-colorable from any list assignment such that all vertices have lists of size two or three and the vertices with list of size two are all incident with the outer face and form an…

Combinatorics · Mathematics 2011-09-15 Zdenek Dvorak , Ken-ichi Kawarabayashi

We show that every plane graph with maximum face size four whose all faces of size four are vertex-disjoint is cyclically 5-colorable. This answers a question of Albertson whether graphs drawn in the plane with all crossings independent are…

Combinatorics · Mathematics 2008-11-18 Daniel Král' , Ladislav Stacho

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…

Combinatorics · Mathematics 2024-07-29 Zdeněk Dvořák , Félix Moreno Peñarrubia

A (k,d)-list assignment L of a graph G is a mapping that assigns to each vertex v a list L(v) of at least k colors and for any adjacent pair xy, the lists L(x) and L(y) share at most d colors. A graph G is (k,d)-choosable if there exists an…

Combinatorics · Mathematics 2016-12-16 Hal Kierstead , Bernard Lidický

A celebrated result of Thomassen states that not only can every planar graph be colored properly with five colors, but no matter how arbitrary palettes of five colors are assigned to vertices, one can choose a color from the corresponding…

Combinatorics · Mathematics 2013-05-10 Maria Axenovich , Joan P. Hutchinson , Michelle A. Lastrina

For positive integers $a$ and $b$, a graph $G$ is $(a:b)$-choosable if, for each assignment of lists of $a$ colors to the vertices of $G,$ each vertex can be colored with a set of $b$ colors from its list so that adjacent vertices are…

Combinatorics · Mathematics 2022-05-23 Glenn G. Chappell

This paper proves that the Alon-Tarsi number of any planar graph is at most $5$, which gives an alternate proof of the $5$-choosability as well as the $5$-paintability of planar graphs.

Combinatorics · Mathematics 2017-11-30 Xuding Zhu

All planar graphs are 4-colorable and 5-choosable, while some planar graphs are not 4-choosable. Determining which properties guarantee that a planar graph can be colored using lists of size four has received significant attention. In terms…

Xu and Wu proved that if every 5-cycle of a planar graph G is not simultaneously adjacent to 3-cycles and 4-cycles, then G is 4-choosable. In this paper, we improve this result as follows. If G is a planar graph without pairwise adjacent…

Combinatorics · Mathematics 2019-01-03 Pongpat Sittitrai , Kittikorn Nakprasit

Xu and Wu proved that if every $5$-cycle of a planar graph $G$ is not simultaneously adjacent to $3$-cycles and $4$-cycles, then $G$ is $4$-choosable. In this paper, we improve this result as follows. Let $\{i, j, k, l\} = \{3,4,5,6\}.$ For…

Combinatorics · Mathematics 2017-09-15 Pongpat Sittitrai , Kittikorn Nakprasit

Let $G$ be a $\{C_4, C_5\}$-free planar graph with a list assignment $L$. Suppose a preferred color is given for some of the vertices. We prove that if all lists have size at least four, then there exists an $L$-coloring respecting at least…

Combinatorics · Mathematics 2020-06-11 Donglei Yang , Fan Yang

We conjecture that every graph of minimum degree five with no separating triangles and drawn in the plane with one crossing is 4-colorable. In this paper, we use computer enumeration to show that this conjecture holds for all graphs with at…

Combinatorics · Mathematics 2025-04-15 Zdeněk Dvořák , Bernard Lidický , Bojan Mohar

By a well-known theorem of Thomassen and a planar graph depicted by Voigt, we know that every planar graph is $5$-choosable, and the bound is tight. In 1999, Lam, Xu and Liu reduced $5$ to $4$ on $C_4$-free planar graphs. In the paper, by…

Combinatorics · Mathematics 2022-11-09 Fan Yang , Yue Wang , Jian-liang Wu

List coloring generalizes graph coloring by requiring the color of a vertex to be selected from a list of colors specific to that vertex. One refinement of list coloring, called choosability with separation, requires that the intersection…

Combinatorics · Mathematics 2015-12-25 Mohit Kumbhat , Kevin Moss , Derrick Stolee
‹ Prev 1 2 3 10 Next ›