Compositions of Regular Coverings and Their Applications
by
J. Šiagiová
Bratislava

Although a composition of two regular coverings need not be regular in general, there are some interesting examples in topological graph theory where a composition of two regular coverings of graphs \pi₁: \Gamma₁ --> \Gamma₀ and \pi₂: \Gamma₂ --> \Gamma₁ is again a regular covering. In such a case all three coverings \pi₁, \pi₂ and \pi₁ o \pi₂ are realizable by voltage assignments, say, \alpha, \beta, and \gamma, in groups H, K, and G, respectively. We give an explicit formula for the group G and a voltage assignment \gamma in terms of H, K, \alpha, and \beta, and illustrate it on an example of graph coverings related to the degree-diameter problem.

Date received: May 26, 2000

Copyright © 2000 by the author(s). The author(s) of this document and the organizers of the conference have granted their consent to include this abstract in Atlas Conferences Inc. Document # cafd-23.