Flow extension with inactive free generators
ProvedOAI.FreeGroupFactorMain.FiniteActive.extension_at_timeThroughout, is the group von Neumann algebra of a discrete group acting on , with canonical trace , left-regular unitaries , and . Let be finite, arbitrary, and let with . Let be finitely supported with self-adjoint, let () be finitely supported real functions on , and let solve with , where is the evaluation of the word in the tuple . Let be the tuple consisting of on and on . For every there is a -preserving ultraweakly continuous -automorphism of such that is the evaluation of in , for every word .
Together with moment preservation, this extends the flow automorphisms of the paper to infinitely many inactive generators.
Formalization Note The statement is verbatim from OpenAI's Lean development, with the listed Definitions imported in place of the upstream modules; the definitions are supporting code for this statement.
import Mathlib import Definitions.Def_FreeGroupFactorProof18 namespace OAI noncomputable section universe uA uι uκ open Set Metric Filter open scoped NNReal Topology BigOperators ContDiff ENNReal attribute [local instance] Classical.propDecidable namespace FreeGroupFactorMain.FiniteActive section open UnitaryEvaluation open scoped ENNReal end open UnitaryEvaluation
theorem extension_at_time {ι : Type uι} {κ : Type uκ} [Fintype ι] [DecidableEq ι] [DecidableEq κ]
(h : ι → FreeGroup ι →₀ ℝ) (l : ℤ →₀ ℂ)
(hS : IsSelfAdjoint (laurentValue (generatorUnitary (none : Option (ι ⊕ κ))) l))
(X : ℝ → ι → Ambient ι κ) (hU : ∀ t i, X t i ∈ unitary (Ambient ι κ))
(hX₀ : X 0 = fun i => groupUnitary (FreeGroup.of (some (Sum.inl i))))
(hX : ∀ t, HasDerivAt X (PolynomialFlow.field
(laurentValue (generatorUnitary (none : Option (ι ⊕ κ))) l) h (X t)) t) (t : ℝ) :
∃ Φ : Ambient ι κ ≃⋆ₐ[ℂ] Ambient ι κ,
(∀ T, canonicalTrace (Φ T) = canonicalTrace T) ∧
@Continuous _ _ (groupUltraweakTopology (FreeGroup (Option (ι ⊕ κ))))
(groupUltraweakTopology (FreeGroup (Option (ι ⊕ κ)))) Φ ∧
∀ g, Φ (groupUnitary g) = wordHom
(extendUnitary (fun j => ⟨tuple (X t) j,tuple_unitary (X t) (hU t) j⟩)
(generatorUnitary none)) g := by
sorry
end FreeGroupFactorMain.FiniteActive
end
end OAI