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Definably compact groups over C((t)) are generically stable and have G^{00} = G^{0} of finite index

Establish that for every definably compact group G definable over the valued field C((t)) in the language of rings: (i) G is generically stable (i.e., admits a generically stable global type), and (ii) the smallest type-definable subgroup of G of bounded index, denoted G^{00}, equals the definable connected component G^{0}, and this subgroup has finite index in G.

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Background

Section 3 develops a weak Lie structure on definable groups over C((t)), enabling a definable topology and the notion of definable compactness for such groups via finitely many affine pieces. It also establishes that fsg groups are definably compact, paralleling results in p-adically closed fields.

Within this framework, the authors propose a revised version of a conjecture from Ling–Yao [1], asserting stronger structural properties of definably compact groups over C((t)), namely generic stability and the identification of G{00} with G{0} as a finite-index subgroup.

References

Conjecture 3.9. Let G be a definably compact group defined over C((t)). Then

  1. G is generically stable;
  2. G00 = Gº is a finite index subgroup of G.
A short note on model theory of C((t)) (2501.12545 - Zhang, 21 Jan 2025) in Conjecture 3.9, Section 3 (Topology on definable groups)