| 摘 要： | Let T be a tree with v vertices. It is said to be graceful if we can label the vertices with numbers 1,2,……,v in such a manner that the differences of any two adjacent vertices will again form the set {1,2,…,v-1}.Ringel conjectured, in1963, that every tree has a such labelling 1]. Ringel's conjecture remains unsettled. In this article, we shall investigate a class of graceful trees. Definition The,T_λ~((n)) is a tree with v_n vertices. Its vertices are v_i(j=0,1,…,n+1);v_(?)(j_o=1,2,…,n;j_1=1,2,…,k_1;……; j=1,2,…,k,≤λ), where λ,n,k_1,
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