Abstract
K. Wagner conjectured that if G1, G2, ... is any countable sequence of finite graphs, then there exist i, j with j > i ≥ 1 such that Gi is isomorphic to a minor of Gj. Kruskal proved this when G1, G2, ... are all trees. We prove a strengthening of Kruskal's result-Wagner's conjecture is true for all sequences in which G1 is planar. We hope to show in a future paper that Wagner's conjecture is true in general, and the results of this paper will be needed for that proof.
Original language | English (US) |
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Pages (from-to) | 227-254 |
Number of pages | 28 |
Journal | Journal of Combinatorial Theory, Series B |
Volume | 48 |
Issue number | 2 |
DOIs | |
State | Published - Apr 1990 |
Externally published | Yes |
All Science Journal Classification (ASJC) codes
- Theoretical Computer Science
- Discrete Mathematics and Combinatorics
- Computational Theory and Mathematics