我们证明最大度Δ≥5的图的无圈色数至多是a(G)≤L(Δ-1)2/2」,这个结果比目前公认的最小上界a(G)=Δ(0-1)/2要小。同时得出两个新的结论:对任意Δ=5的图G,有a(G)≤8;对任意Δ=6的图G,有a(G)≤12。
Any graph with maximum degree Δ≥5 has acyclic chromatic number at most a(G)≤L(Δ-1)2/2」 is proved.This result is less than the best general upper bound a(G)≤Δ(Δ-1)/2.and two new conclvsions are drew as follows:a(G)≤8,if any graph of Δ=5;a(G)≤12,if any graph of Δ=6.