It is shown that, if t is an integer !3 and not equal to 7 or 8, then there is a unique maximal graph having the path P t as a star complement for the eigenvalue ร2: The maximal graph is the line graph of K m,m if t ยผ 2mร1, and of K m,m รพ1 if t ยผ 2m. This result yields a characterization of L(G ) wh
Excluding a bipartite circle graph from line graphs
โ Scribed by Sang-il Oum
- Publisher
- John Wiley and Sons
- Year
- 2009
- Tongue
- English
- Weight
- 215 KB
- Volume
- 60
- Category
- Article
- ISSN
- 0364-9024
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โฆ Synopsis
Abstract
We prove that, for a fixed bipartite circle graph H, all line graphs with sufficiently large rankโwidth (or cliqueโwidth) must have a pivotโminor isomorphic to H. To prove this, we introduce graphic deltaโmatroids. Graphic deltaโmatroids are minors of deltaโmatroids of line graphs and they generalize graphic and cographic matroids. ยฉ 2008 Wiley Periodicals, Inc. J Graph Theory 60: 183โ203, 2009
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