A Simpler Proof of the Excluded Minor Theorem for Higher Surfaces
β Scribed by Carsten Thomassen
- Publisher
- Elsevier Science
- Year
- 1997
- Tongue
- English
- Weight
- 223 KB
- Volume
- 70
- Category
- Article
- ISSN
- 0095-8956
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β¦ Synopsis
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 theory, we obtain a simpler proof of the generalized Kuratowski theorem for each fixed surface. The proof requires no previous knowledge of graph embeddings.
1997 Academic Press We define the grid J k as a finite subgraph of the hexagonal tiling of the Euclidean plane. We let J 1 be a cycle of length 6. For each k 2, we define J k as the union of J k&1 and all those 6-cycles in the hexagonal grid which intersect J k&1 . Clearly, J k is a subdivision of a 3-connected graph when k>1. With this notation [8,9] imply article no. TB971761 306 0095-8956Γ97 25.00
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