Flows and joins of metric spaces

By Igor Mineyev. 2005

79 citations recorded by the source corpus.

We introduce the functor ◦ which assigns to every metric space X its symmetric join ◦X. As a set, ◦X is a union of intervals connecting ordered pairs of points in X. Topologically, ◦X is a natural quotient of the usual join of X with itself. We define an Isom(X)–invariant metric d∗ on ◦X. Classical concepts known for H n and negatively curved manifolds are defined in a precise way for any hyperbolic complex X, for example for a Cayley graph of a Gromov hyperbolic group. We define a double difference, a cross-ratio and horofunctions in the compactification ¯ X = X ⊔ ∂X. They are continuous, Isom(X)–invariant, and satisfy sharp identities. We characterize the translation length of a hyperbolic isometry g ∈ Isom(X). For any hyperbolic complex X, the symmetric join ◦ ¯ X of ¯ X and the (generalized) metric d∗ on it are defined. The geodesic flow space F(X) arises as a part of ◦ ¯ X. (F(X), d∗) is an analogue of (the total space of) the unit tangent bundle on a simply connected negatively curved manifold. This flow space is defined for any hyperbolic complex X and has sharp properties. We also give a construction of the asymmetric join X ◦ Y of two metric spaces. These concepts are canonical, i.e. functorial in X, and involve no “quasi”-language. Applications and relation to the Borel conjecture and others are discussed. AMS Classification numbers Primary: 20F65, 20F67, 37D40, 51F99, 57Q05 Secondary: 57M07, 57N16, 57Q91, 05C25

Subfields: Geometry and Topology, Mathematical Physics

View Paper: https://www.semanticscholar.org/paper/0006862669163993d91ead9a438eac415d81037a

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In Geometry and Topology

  1. Anna Wienhard
  2. Andr'es Sambarino
  3. Michael Kapovich
  4. B. Leeb
  5. J. Porti
  6. Olivier Y Guichard
  7. W. Lück
  8. Rafael Potrie

In Mathematical Physics

  1. Anna Wienhard
  2. Andr'es Sambarino
  3. Michael Kapovich
  4. B. Leeb
  5. Rafael Potrie
  6. J. Porti
  7. W. Lück
  8. Arthur Bartels

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