## Abstract A __covering__ is a graph map Ο: __G__ β __H__ that is an isomorphism when restricted to the star of any vertex of __G__. If __H__ is connected then |Ο^β1^(__v__)| is constant. This constant is called the __fold number__. In this paper we prove that if __G__ is a planar graph that cover
On the Parity of Colourings and Flows
β Scribed by Andrew J. Goodall; Dominic J.A. Welsh
- Publisher
- Elsevier Science
- Year
- 2002
- Tongue
- English
- Weight
- 53 KB
- Volume
- 84
- Category
- Article
- ISSN
- 0095-8956
No coin nor oath required. For personal study only.
β¦ Synopsis
We extend a result of Tarsi and show that the chromatic polynomial and flow polynomial evaluated at 1+k are up to sign the same modulo k 2 for any integer k such that |k| \ 2.
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