ON n-TOTAL CHROMATIC NUMBER OF A GRAPH AND ITS COMPLEMENT GRAPH
张忠辅, 孙良 · 中国科学通报：英文版 · 1991
Let G(V, E) be a simple graph, f: C→V(G) be an injection, and all vertices on the path whose length is no longer than n be assigned different colors, where C is a color set. Then f is called an n-coloring of G. If |C|=m, f is called m-n-coloring graph, G m-n-colorable if there exists a k-n-coloring of G for some k≤m.