On(ξ,1)-Critical Graphs and Upper Embeddability
Huang Yuan-qiu · Journal of Jishou University · 2010
Let G be a connected graph with ξ(G)=k≥1.If ξ(G\e)=k-1,G is called to be a(ξ,1)-critical graph.This paper gives the upper embeddability of the ξ-1-critical graphs,and shows that extension of a vertex and extension of a cycle dose not change the ξ-1-cirtical graphs.The new upper embeddable graphs are obtained,enriching the kind and seeking methods.