2018 | OriginalPaper | Chapter
External Topological Phenomena
Authors : Thierry Giordano, David Kerr, N. Christopher Phillips, Andrew Toms
Published in: Crossed Products of C*-Algebras, Topological Dynamics, and Classification
Publisher: Springer International Publishing
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Complementing the internal finite modelling property of local finiteness is the external property of local embeddability into finite groups, which is the topological (i.e., purely group-theoretic, since our groups are discrete) analogue of soficity. The group G is said to be LEF (locally embeddable into finite groups) if for every finite set F ⊆ G there is a finite group H and a map σ : G → H such that σ(st) = σ(s)σ(t) for all s, t ∊ F and σ|F is injective. This notion was introduced by Gordon and Vershik in [33].