A graph is antipodal if, for every vertex c', there exists exactly one vertex V which is not closer to r than every vertex adjacent to 6. In this paper we consider the problem of characterizing tope graphs of oriented matroids, which constitute a broad class of antipodal graphs. One of the results i
Spatial Graphs and Oriented Matroids: the Trefoil
β Scribed by J. L. Ramirez Alfonsin
- Publisher
- Springer
- Year
- 1999
- Tongue
- English
- Weight
- 165 KB
- Volume
- 22
- Category
- Article
- ISSN
- 0179-5376
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π SIMILAR VOLUMES
We consider the cocircuit graph G M of an oriented matroid M, which is the 1-skeleton of the cell complex formed by the span of the cocircuits of M. As a result of Cordovil, Fukuda, and Guedes de Oliveira, the isomorphism class of M is not determined by G M , but it is determined if M is uniform and
An element e of a 3-connected matroid M is essential if neither the deletion M\e nor the contraction M/e is 3-connected. Tutte's Wheels and Whirls Theorem proves that the only 3-connected matroids in which every element is essential are the wheels and whirls. In this paper, we consider those 3-conne
## Abstract A homomorphism from an oriented graph __G__ to an oriented graph __H__ is a mapping $\varphi$ from the set of vertices of __G__ to the set of vertices of __H__ such that $\buildrel {\longrightarrow}\over {\varphi (u) \varphi (v)}$ is an arc in __H__ whenever $\buildrel {\longrightarrow}