Inventiones mathematicae

, Volume 117, Issue 1, pp 373–389

Equivalence of the strengthened Hanna Neumann conjecture and the amalgamated graph conjecture

Authors

  • Warren Dicks
    • Departament de MatemàtiquesUniversitat Autònoma de Barcelona
Article

DOI: 10.1007/BF01232249

Cite this article as:
Dicks, W. Invent Math (1994) 117: 373. doi:10.1007/BF01232249

Summary

We show that Walter Neumann's strengthened form of Hanna Neumann's conjecture on the best possible upper bound for the rank of the intersection of two subgroups of a free group is equivalent to a conjecture on the best possible upper bound for the number of edges in a bipartite graph with a certain weak symmetry condition. We illustrate the usefulness of this equivalence by deriving relatively easily certain previously known results.

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Copyright information

© Springer-Verlag 1994