## It is proved that a planar graph G without five cycles is three degenerate, hence, four choosable, and it is also edge-(A( G) + l)-h
A not 3-choosable planar graph without 3-cycles
β Scribed by Margit Voigt
- Publisher
- Elsevier Science
- Year
- 1995
- Tongue
- English
- Weight
- 140 KB
- Volume
- 146
- Category
- Article
- ISSN
- 0012-365X
No coin nor oath required. For personal study only.
β¦ Synopsis
An L-list coloring of a graph G is a proper vertex coloring in which every vertex v receives a color from a prescribed list L(v). G is called k-choosable if all lists L(v) have the cardinality k and G is L-list colorable for all possible assignments of such lists.
Recently, Thomassen has proved that every planar graph with girth greater than 4 is 3-choosable. Furthermore, it is known that the chromatic number of a planar graph without 3-cycles is at most 3. Consequently, the question resulted whether every planar graph without 3-cycles is 3-choosable.
In the following we will give a planar graph without 3-cycles which is not 3choosable.
π SIMILAR VOLUMES
## Abstract A proper vertex coloring of a graph __G__β=β(__V,E__) is acyclic if __G__ contains no bicolored cycle. A graph __G__ is acyclically __L__βlist colorable if for a given list assignment __L__β=β{__L__(__v__): __v__:βββ__V__}, there exists a proper acyclic coloringβΟβof __G__ such that Ο(_
## Abstract A proper vertex coloring of a graph __G__=(__V, E__) is acyclic if __G__ contains no bicolored cycle. A graph __G__ is acyclically __L__βlist colorable if for a given list assignment __L__={__L__(__v__)|__v__β__V__}, there exists a proper acyclic coloring Ο of __G__ such that Ο(__v__)β_
The conjecture on acyclic 5-choosability of planar graphs [Borodin et al., 2002] as yet has been verified only for several restricted classes of graphs. None of these classes allows 4-cycles. We prove that a planar graph is acyclically 5-choosable if it does not contain an i-cycle adjacent to a j-cy
An L-list coloring of a graph G is a proper vertex coloring in which every vertex v gets a color from a list L(v) of allowed colors. G is called k-choosable if all lists L(v) have exactly k elements and if G is L-list colorable for all possible assignments of such lists. Verifying conjectures of Erd