In this paper we enumerate the rooted dual loopless nonseparable near-triangular maps on the sphere and the projective plane with the valency of root-face and the number of inner faces as parameters. Explicit expressions of enumerating functions are derived for such maps on the sphere and the projective plane. A parametric expression of the generating function is obtained for the rooted 2-connected triangular maps on the projective plane, from which asymptotics evaluations are derived.
结合边连通度,探讨了独立集中具有最小特定度和的点的上可嵌入图.得到了下列结果.(1)设G是一个2-边连通简单图且满足条件：对任意一个G的3-独立集I,x_i,x_j∈I(i,j=1,2,3),d(x_i,x_j)≥3(1≤i≠j≤3)sum from i=1 to 3 d(x_i)≥v+1 (v=V(G)),则G是上可嵌入的；(2)设G是一个3-边连通简单图且满足条件：对任意一个G的6-独立集I,x_i,x_j∈I(i,j=1,2,3,4,5,6),d(x_i,x_j)≥3(1≤i≠j≤6)sum from i=1 to 6 d(x_i)≥v+1(v=|V(G)|),则G是上可嵌入的.
In this paper, we show that for a locally LEW-embedded 3-connected graph G in orientable surface, the following results hold： 1） Each of such embeddings is minimum genus embedding; 2） The facial cycles are precisely the induced nonseparating cycles which implies the uniqueness of such embeddings; 3） Every overlap graph O（G, C） is a bipartite graph and G has only one C-bridge H such that C U H is nonplanar provided C is a contractible cycle shorter than every noncontractible cycle containing an edge of C. This extends the results of C Thomassen＇s work on LEW-embedded graphs.
