## Abstract We give a detailed algebraic characterization of when a graph __G__ can be imbedded in the projective plane. The characterization is in terms of the existence of a dual graph __G__\* on the same edge set as __G__, which satisfies algebraic conditions inspired by homology groups and inte
An algebraic characterization of planar graphs
β Scribed by Dan Archdeacon; C. Paul Bonnington; Charles H. C. Little
- Publisher
- John Wiley and Sons
- Year
- 1995
- Tongue
- English
- Weight
- 773 KB
- Volume
- 19
- Category
- Article
- ISSN
- 0364-9024
No coin nor oath required. For personal study only.
β¦ Synopsis
Abstract
A cycle in a graph is a set of edges that covers each vertex an even number of times. A cocycle is a collection of edges that intersects each cycle in an even number of edges. A bicycle is a collection of edges that is both a cycle and a cocycle. The cycles, cocycles, and bicycles each form a vector space over the integers modulo two when addition is defined as symmetric difference of sets. In this paper we examine the relationship between the leftβright paths in a planar graph and the cycle space, cocylce space, and bicycle space. We show that planar graphs are characterized by the existence of a diagonalβa double cover by tours that interacts with the cycle space, cocycle space, and bicycle space in a special manner. This generalizes a result of Rosenstiehl and Read that characterized those planar graphs with no nonempty bicycles. Β© 1995 John Wiley & Sons, Inc.
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