Abstract
We show that the problem of the existence of universal graphs with specified forbidden subgraphs can be systematically reduced to certain critical cases by a simple pruning technique which simplifies the underlying structure of the forbidden graphs, viewed as trees of blocks. As an application, we characterize the trees T for which a universal countable T-free graph exists.
Original language | English |
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Pages (from-to) | 293-333 |
Number of pages | 41 |
Journal | Journal of Combinatorial Theory. Series B |
Volume | 97 |
Issue number | 3 |
DOIs | |
State | Published - May 2007 |
Keywords
- Forbidden subgraph
- Graph
- Model theory
- Tree
- Universal graph