Czasopismo
Tytuł artykułu
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Abstrakty
The main results of the paper are:
Proposition 0.1. A group G acting coarsely on a coarse space (X,𝓒) induces a coarse equivalence g ↦ g·x₀ from G to X for any x₀ ∈ X.
Theorem 0.2. Two coarse structures 𝓒₁ and 𝓒₂ on the same set X are equivalent if the following conditions are satisfied:
(1) Bounded sets in 𝓒₁ are identical with bounded sets in 𝓒₂.
(2) There is a coarse action ϕ₁ of a group G₁ on (X,𝓒₁) and a coarse action ϕ₂ of a group G₂ on (X,𝓒₂) such that ϕ₁ commutes with ϕ₂.
They generalize the following two basic results of coarse geometry:
Proposition 0.3 (Shvarts-Milnor lemma [5, Theorem 1.18]). A group G acting properly and cocompactly via isometries on a length space X is finitely generated and induces a quasi-isometry equivalence g ↦ g·x₀ from G to X for any x₀ ∈ X.
Theorem 0.4 (Gromov [4, p. 6]). Two finitely generated groups G and H are quasi-isometric if and only if there is a locally compact space X admitting proper and cocompact actions of both G and H that commute.
Proposition 0.1. A group G acting coarsely on a coarse space (X,𝓒) induces a coarse equivalence g ↦ g·x₀ from G to X for any x₀ ∈ X.
Theorem 0.2. Two coarse structures 𝓒₁ and 𝓒₂ on the same set X are equivalent if the following conditions are satisfied:
(1) Bounded sets in 𝓒₁ are identical with bounded sets in 𝓒₂.
(2) There is a coarse action ϕ₁ of a group G₁ on (X,𝓒₁) and a coarse action ϕ₂ of a group G₂ on (X,𝓒₂) such that ϕ₁ commutes with ϕ₂.
They generalize the following two basic results of coarse geometry:
Proposition 0.3 (Shvarts-Milnor lemma [5, Theorem 1.18]). A group G acting properly and cocompactly via isometries on a length space X is finitely generated and induces a quasi-isometry equivalence g ↦ g·x₀ from G to X for any x₀ ∈ X.
Theorem 0.4 (Gromov [4, p. 6]). Two finitely generated groups G and H are quasi-isometric if and only if there is a locally compact space X admitting proper and cocompact actions of both G and H that commute.
Słowa kluczowe
Kategorie tematyczne
- 20H15: Other geometric groups, including crystallographic groups
- 54D40: Remainders
- 54E35: Metric spaces, metrizability
- 54C55: Absolute neighborhood extensor, absolute extensor, absolute neighborhood retract (ANR), absolute retract spaces (general properties)
- 18B30: Categories of topological spaces and continuous mappings
- 54D35: Extensions of spaces (compactifications, supercompactifications, completions, etc.)
- 54F45: Dimension theory
Czasopismo
Rocznik
Tom
Numer
Strony
149-158
Opis fizyczny
Daty
wydano
2008
Twórcy
autor
- Department of Mathematics, University of Tennessee, Knoxville, TN 37996, U.S.A.
autor
- Department of Mathematics, University of Tennessee, Knoxville, TN 37996, U.S.A.
autor
- Department of Mathematics, University of Tennessee, Knoxville, TN 37996, U.S.A.
Bibliografia
Typ dokumentu
Bibliografia
Identyfikatory
Identyfikator YADDA
bwmeta1.element.bwnjournal-article-doi-10_4064-cm111-1-13
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