The natural extension of MacLane's combinatorial approach to planar imbeddings is seen to yield a combinatorial formulation of imbedding of a graph in a pseudosurface. This leads to a combinatorially defined parameter for all graphs, called the imbedding index. A generalization of the Heaword inequality is then proved for this parameter.
ASJC Scopus subject areas
- Theoretical Computer Science
- Discrete Mathematics and Combinatorics
- Computational Theory and Mathematics