Enumeration of projective-planar embeddings of graphs

Seiya Negami
1986 Discrete Mathematics  
It will be shown that the number of equivalence classes of embeddings of a 3-connected nonplanar graph into a projective plane coincides with the number of isomorphism classes of planar double coverings of the graph and a combinatorial method to determine the number will be developed.
doi:10.1016/0012-365x(86)90217-7 fatcat:vhb2ffxdizhztaq6rwrwgzhvce