A note on the list vertex arboricity of toroidal graphs

Abstract The vertex arboricity a ( G ) of a graph G is the minimum number of colors required to color the vertices of G such that no cycle is monochromatic. The list vertex arboricity a l ( G ) is the list-coloring version of this concept. In this note, we prove that if G is a toroidal graph, then a l ( G ) ≤ 4 ; and a l ( G ) = 4 if and only if G contains K 7 as an induced subgraph.