Adjacent Vertex Distinguishing Total Colorings of Outer 1-Planar Graphs

Qin Chen1
1College of Science, China Jiliang University, Hangzhou 310018, P.R. China

Abstract

An adjacent vertex distinguishing total coloring of a graph \(G\) is a proper total coloring of \(G\) such that no pair of adjacent vertices are incident to the same set of colors. The minimum number of colors required for an adjacent vertex distinguishing total coloring of \(G\) is denoted by \(\chi”_a(G)\). In this paper, we prove that if \(G\) is an outer 1-planar graph with at least two vertices, then \(\chi”_a(G) \leq \max\{\Delta + 2, 8\}\). Moreover, we also prove that when \(\Delta \geq 7\), \(\chi”_a(G) = \Delta + 2\) if and only if \(G\) contains two adjacent vertices of maximum degree.

Keywords: Adjacent vertex distinguishing total coloring, Outer 1-planar graph, Maximum degree.