Graphs 2-cell embedded in non-orientable surfaces and their coding sequences

Coding sequences are a simple and natural means of representing graphs. In applying coding sequences to graphs in non-orientable surfaces, we clarify on what it means for a graph to be 2-cell embedded in the Mbius band and in the projective plane; in particular, examples are given of the degenerate situation where the complement of a face in the projective plane is not a true Mbius band. Taking the matter of degeneracy into account, via coding sequences, we give rigorous proofs of Euler characteristic formulas for non-orientable surfaces. The matter of degeneracy had not been previously considered in this context. 2008 Pushpa Publishing House.

Graphs 2-cell embedded in non-orientable surfaces and their coding sequences Academic Article