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图G的点荫度a(G)是用来染G的顶点集合的最少颜色数使得不产生单色圈.列表点荫度al(G)是这个概念在列表染色意义下的推广.本文证明了:若G是一个直径为2的可平面图,则al(G)≤2.“,”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 al (G) is the list version of this concept.In this paper,we prove that if G is a planar graph of diameter at most two,then al (G) ≤ 2.