摘要
ErdOs,Gimbel and Straight （1990） conjectured that if ω（G）〈5 and z（G）〉3,then z（G）≥Z（G）-2. But by using the concept of edge cochromatic number it is proved that if G is the line graph of a connected triangle-free graph with ω（G）〈5 and G≠K4, then z（G）≥X（G）-2.
ErdOs,Gimbel and Straight （1990） conjectured that if ω（G）〈5 and z（G）〉3,then z（G）≥Z（G）-2. But by using the concept of edge cochromatic number it is proved that if G is the line graph of a connected triangle-free graph with ω（G）〈5 and G≠K4, then z（G）≥X（G）-2.
基金
Supported by the Natural Science Foundation of Gansu Province (3ZS051-A25-025).
