Weinberg bounds over nonspherical graphs
SCIE
SCOPUS
- Title
- Weinberg bounds over nonspherical graphs
- Authors
- Chen, BF; Kwak, JH; Lawrencenko, S
- Date Issued
- 2000-04
- Publisher
- JOHN WILEY & SONS INC
- Abstract
- Let Aut(G) and E(G) denote the automorphism group and the edge set of a graph G, respectively. Weinberg's Theorem states that 4 is a constant sharp upper bound on the ratio \Aut(G)\/\E(G)\ over planar (or spherical) 3-connected graphs G. We have obtained various analogues of this theorem for nonspherical graphs, introducing two Weinberg-type bounds for an arbitrary closed surface Sigma, namely: W-P(Sigma) and W-T (Sigma) (=) (def) (G) (sup) \Aut(G)\/\E(G)\, where supremum is taken over the polyhedral graphs G with respect to C for W-P(Sigma) and over the graphs G triangulating Sigma for W-T (Sigma). We have proved that Weinberg bounds are finite for any surface; in particular: W-P = W-T = 48 for the projective plane, and W-T = 240 for the torus. We have also proved that the original Weinberg bound of 4 holds over the graphs G triangulating the projective plane with at least 8 vertices and, in general, for the graphs of sufficiently large order triangulating a fixed closed surface Sigma. (C) 2000 John Wiley & Sons, Inc.
- Keywords
- automorphism group; 3-connected graph; surface; triangulation; PROJECTIVE PLANE; TRIANGULATIONS
- URI
- https://oasis.postech.ac.kr/handle/2014.oak/20069
- DOI
- 10.1002/(SICI)1097-0118(200004)33:4<220::AID-JGT3>3.0.CO;2-Z
- ISSN
- 0364-9024
- Article Type
- Article
- Citation
- JOURNAL OF GRAPH THEORY, vol. 33, no. 4, page. 220 - 236, 2000-04
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