Chang models over derived models with supercompact measures
Takehiko Gappo, Sandra Müller, Grigor Sargsyan
TL;DR
The paper constructs Chang-type determinacy models over derived hod-derived models to obtain rich structure above $\Theta$ and, crucially, to realize $\omega_1$ with strong large-cardinal properties. By developing the Chang model over the derived model, $\mathsf{CDM}^{+}$, inside a symmetric collapse of a hod mouse, it proves $\mathsf{AD}^{+}+\mathsf{AD}_{\mathbb{R}}$ and establishes $\omega_1$ as $<{\delta}_{\infty}$-supercompact for a suitably large regular ${\delta}_{\infty}>\Theta$, with $\Theta$ regular and even measurable under stronger hypotheses. The construction relies on a directed system of genericity iterations yielding a robust direct-limit model $\mathcal{M}_{\infty}(\mathcal{Q},\eta)$ and club-filter-based ultrafilters, enabling $\Theta$-measurability and $\omega_1$-supercompactness within $\mathsf{CDM}^{+}$. These results extend Woodin's generalized Chang model by providing a determinacy framework with supercompactness properties tied to a derived-model backbone, offering weaker consistency-strength assumptions than traditional Woodin-limit frameworks and broadening the landscape of determinacy with large-cardinal features.
Abstract
Based on earlier work of the third author, we construct a Chang-type model with supercompact measures extending a derived model of a given hod mouse with a regular cardinal $δ$ that is both a limit of Woodin cardinals and a limit of ${<}δ$-strong cardinals. The existence of such a hod mouse is consistent relative to a Woodin cardinal that is a limit of Woodin cardinals. We argue that our Chang-type model satisfies $\mathsf{AD}_{\mathbb{R}} + Θ$ is regular + $ω_1$ is ${<}δ_{\infty}$-supercompact for some regular cardinal $δ_{\infty}>Θ$. This complements Woodin's generalized Chang model, which satisfies $\mathsf{AD}_{\mathbb{R}}+ω_1$ is supercompact, assuming a proper class of Woodin cardinals that are limits of Woodin cardinals.
