Yufa Shen

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Note The integral sum number of complete bipartite graphs K r; s Abstract A graph G =(V; E) is said to be an integral sum graph (sum graph) if its vertices can be given a labeling with distinct integers (positive integers), so that uv ∈ E if and only if u + v ∈ V. The integral sum number (sum number) of a given graph G, denoted by (G) ((G)), was deÿned as(More)
A graph G is said to be chromatic-choosable if ch(G) = χ(G). Ohba has conjectured that every graph G with 2χ(G) + 1 or fewer vertices is chromatic-choosable. It is clear that Ohba's conjecture is true if and only if it is true for complete multipartite graphs. In this paper we show that Ohba's conjecture is true for complete multipartite graphs K 4,3 * t,2(More)