Model completeness conjecture for the universally Baire Chang model

From papers

Assume MAX(UB)\mathbf{MAX}(\mathsf{UB}) and ()-UB(*)\text{-}\mathsf{UB}. Let Θ\Theta be the supremum of the ordinals α\alpha which are the surjective image of some ϕ:2ωOrd\phi:2^\omega\to\operatorname{Ord} existing in L(UB)L(\mathsf{UB}). Here LΘ(UBω1)L_\Theta(\mathsf{UB}^{\omega_1}) denotes the corresponding level of the constructible hierarchy with universally Baire predicates, and Δ1{ω1,NSω1,UB}\in_{\Delta_1}\cup\{\omega_1,\mathbf{NS}_{\omega_1},\mathsf{UB}\} is the indicated signature, where UB\mathsf{UB} detects which subsets of 2ω2^\omega are universally Baire.

Model completeness conjecture. The theory of LΘ(UBω1)L_\Theta(\mathsf{UB}^{\omega_1}) is model complete for the signature

Δ1{ω1,NSω1,UB}.\in_{\Delta_1}\cup\{\omega_1,\mathbf{NS}_{\omega_1},\mathsf{UB}\}.

This conjecture concerns improving the model-completeness consequences of Woodin-style axioms. It does not assert that Θ\Theta is regular in VV; the source notes that Θ\Theta could have cofinality ω2\omega_2, while conjecturally not ω1\omega_1, and that an argument of Woodin combined with other results should show that Θ\Theta is not regular in models of MM+++\mathsf{MM}^{+++}.

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Sources & referencesView supporting material

Primary source

Matteo Viale, “Absolute model companionship, forcibility, and the continuum problem”, arXiv:2109.02285 (2022).

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