图G的孤立韧度定义为I(G)=min{|S|/i(G—S):S包含于V(G),i(G—S)≥2},若G不是完全图;否则,令I(G)=∞。论文给出了图的分数[a,b]因子的存在性与图的孤立韧度的关系。证明若δ(G)≥,(G)≥a-1+a/b,则图G^+有分数[a,b]-因子,其中a〈b均为正整数。进一步地,证明了该结果在一定意义下是最好的。
The isolated toughness of G is defined as I(G)=min{|S|/i(G-S):Slohtvin inV(G),i(G-S)≥2} if G is not complete Otherwise,set l(G)=∞.In this paper,the relationships between the isolated toughness and the existence of fractional [a, b]-faetors are given.h is proved that if δ(G)≥I(G)≥a-1+a/b,then G has a fractional [a,b]-faetor where a〈b.Furthermore ,it is showed that the results in this paper are best possible in some sense.