Generic Representations of Finitely Generated Groups on Fraisse Structures

نویسنده

  • CHRISTIAN ROSENDAL
چکیده

For finitely generated groups Γ and ultrahomogeneous countable relational structures M we study the space Rep(Γ,M) of all representations of Γ by automorphisms on M equipped with the topology it inherits seen as a closed subset of Aut(M)Γ. When Γ is the free group Fn on n generators this space is just Aut(M)n, but is in general significantly more complicated. We prove that when Γ is finitely generated abelian and M the random structure of a finite relational language or the random ultrametric space of a countable distance set there is a generic point in Rep(Γ,M), i.e., there is a comeagre set of mutually conjugate representations of Γ on M. This is analogous to results of Hrushovski, Herwig, and Herwig–Lascar for the case Γ = Fn.

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تاریخ انتشار 2007