Two embeddings of a graph in a surface S are said to be ``equivalent'' if they are identical under an homeomorphism of S that is orientation-preserving for orientable S. Two graphs cellularly embedded simultaneously in S are said to be ``jointly embedded'' if the only points of intersection involve
Two maps with large representativity on one surface
β Scribed by R. Bruce Richter; Gelasio Salazar
- Publisher
- John Wiley and Sons
- Year
- 2005
- Tongue
- English
- Weight
- 120 KB
- Volume
- 50
- Category
- Article
- ISSN
- 0364-9024
No coin nor oath required. For personal study only.
β¦ Synopsis
Abstract
We show that, for each orientable surface Ξ£, there is a constant c~Ξ£~ so that, if G~1~ and G~2~ are embedded simultaneously in Ξ£, with representativities r~1~ and r~2~, respectively, then the minimum number cr(G~1~, G~2~) of crossings between the two maps satisfies
This refines earlier estimates by Negami. Furthermore, we provide a counterexample to a conjecture of Archdeacon and Bonnington by exhibiting, for each k, embeddings G~1~ and G~2~ in the double torus so that, if we force all the vertices of G~1~ to be in the same face of G~2~, then the number of crossings between G~1~ and G~2~ is at least kβΒ·βcr(G~1~, G~2~). Β© 2005 Wiley Periodicals, Inc.
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