# Every Planar Graph Without Pairwise Adjacent 3-, 4-, and 5-Cycle is DP-4-Colorable

Article

## Abstract

DP-coloring is a generalization of list coloring in simple graphs. Many results in list coloring can be generalized in those of DP-coloring. Kim and Ozeki showed that every planar graph without k-cycles where $$k=3,4,5,$$ or 6 is DP-4-colorable. Recently, Kim and Yu extended the result on 3- and 4-cycles by showing that every planar graph without triangles adjacent to 4-cycles are DP-4-colorable. Xu and Wu showed that every planar graph without 5-cycles adjacent simultaneously to 3-cycles and 4-cycles is 4-choosable. In this paper, we extend the results on 3-, 4-, and 5-cycles as follows. Let G be a planar graph without pairwise adjacent 3-, 4-, and 5-cycle. We prove that each precoloring of a 3-cycle of G can be extended to a DP-4-coloring of G. As a consequence, each planar graph without pairwise adjacent 3-, 4-, and 5-cycle is DP-4-colorable.

## Keywords

DP-coloring List coloring Planar graph Cycle

05C15

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© Malaysian Mathematical Sciences Society and Penerbit Universiti Sains Malaysia 2019

## Authors and Affiliations

• Pongpat Sittitrai
• 1
• Kittikorn Nakprasit
• 1
1. 1.Department of Mathematics, Faculty of ScienceKhon Kaen UniversityKhon KaenThailand

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