In this article it is shown that every 4-connected graph that does not contain a minor isomorphic to the octahedron is isomorphic to the square of an odd cycle.
On the Excluded Minors for Quaternary Matroids
✍ Scribed by J.F. Geelen; J.G. Oxley; D.L. Vertigan; G.P. Whittle
- Publisher
- Elsevier Science
- Year
- 2000
- Tongue
- English
- Weight
- 221 KB
- Volume
- 80
- Category
- Article
- ISSN
- 0095-8956
No coin nor oath required. For personal study only.
✦ Synopsis
This paper strengthens the excluded-minor characterization of GF(4)-representable matroids. In particular, it is shown that there are only finitely many 3-connected matroids that are not GF(4)-representable and that have no U 2, 6 -, U 4, 6 -, P 6 -, F & 7 -, or (F & 7 )*-minors. Explicitly, these matroids are all minors of S(5, 6, 12) with rank and corank at least 4, and P" 8 , the matroid that can be obtained from S(5, 6, 12) by deleting two elements, contracting two elements, and then relaxing the only pair of disjoint circuit-hyperplanes.
📜 SIMILAR VOLUMES
## Abstract Let __G__ be the unique 4‐connected simple graph obtained by adding an edge to the Octahedron. Every 4‐connected graph that does not contain a minor isomorphic to __G__ is either planar or the square of an odd cycle. © 2007 Wiley Periodicals, Inc. J Graph Theory 57: 124–130, 2008
We give a simple proof of the fact (which follows from the Robertson Seymour theory) that a graph which is minimal of genus g cannot contain a subdivision of a large grid. Combining this with the tree-width theorem and the quasi-wellordering of graphs of bounded tree-width in the Robertson Seymour t
dedicated to the memory of gian-carlo rota ## 1. THE UNIMODALITY CONJECTURE Although Gian-Carlo Rota did not publish much in matroid theory, his influence on the subject is pervasive (see ). Among the many conjectures bearing his name in matroid theory, the unimodality conjecture is perhaps the mo
In this paper we study the question of existence of a basis consisting only of cycles for the lattice Z(M) generated by the cycles of a binary matroid M. We show that if M has no Fano dual minor, then any set of fundamental circuits can be completed to a cycle basis of Z(M); moreover, for any one-el
We present a new direct proof of the Folkman-Lawrence topological representation theorem for oriented matroids of rank 3.