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Transactions of the American Mathematical Society

Published by the American Mathematical Society since 1900, Transactions of the American Mathematical Society is devoted to longer research articles in all areas of pure and applied mathematics.

ISSN 1088-6850 (online) ISSN 0002-9947 (print)

The 2020 MCQ for Transactions of the American Mathematical Society is 1.48.

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Well-quasi-ordering infinite graphs with forbidden finite planar minor
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by Robin Thomas PDF
Trans. Amer. Math. Soc. 312 (1989), 279-313 Request permission

Abstract:

We prove that given any sequence ${G_1},{G_2}, \ldots$ of graphs, where ${G_1}$ is finite planar and all other ${G_i}$ are possibly infinite, there are indices $i,j$ such that $i < j$ and ${G_i}$ is isomorphic to a minor of ${G_j}$ . This generalizes results of Robertson and Seymour to infinite graphs. The restriction on ${G_1}$ cannot be omitted by our earlier result. The proof is complex and makes use of an excluded minor theorem of Robertson and Seymour, its extension to infinite graphs, Nash-Williams’ theory of better-quasi-ordering, especially his infinite tree theorem, and its extension to something we call tree-structures over ${\text {QO}}$-categories, which includes infinitary version of a well-quasi-ordering theorem of Friedman.
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Additional Information
  • © Copyright 1989 American Mathematical Society
  • Journal: Trans. Amer. Math. Soc. 312 (1989), 279-313
  • MSC: Primary 05C99; Secondary 04A20
  • DOI: https://doi.org/10.1090/S0002-9947-1989-0932450-9
  • MathSciNet review: 932450