Supercompactness and failures of GCH

Sy-David Friedman ; Radek Honzik

Fundamenta Mathematicae, Tome 219 (2012), p. 15-36 / Harvested from The Polish Digital Mathematics Library

Résumé

Let κ < λ be regular cardinals. We say that an embedding j: V → M with critical point κ is λ-tall if λ < j(κ) and M is closed under κ-sequences in V. Silver showed that GCH can fail at a measurable cardinal κ, starting with κ being κ⁺⁺-supercompact. Later, Woodin improved this result, starting from the optimal hypothesis of a κ⁺⁺-tall measurable cardinal κ. Now more generally, suppose that κ ≤ λ are regular and one wishes the GCH to fail at λ with κ being λ-supercompact. Silver’s methods show that this can be done starting with κ being λ⁺⁺-supercompact (note that Silver’s result above is the special case when κ = λ). One can ask if there is an analogue of Woodin’s result for λ-supercompactness. We answer this question in the following strong sense: starting with the GCH and κ being λ-supercompact and λ⁺⁺-tall, we preserve λ-supercompactness of κ and kill the GCH at λ by directly manipulating the size of $2^{λ}$ (i.e. we do not force the failure of GCH at λ as a consequence of having $2^{κ}$ large enough). The direct manipulation of $2^{λ}$, where λ can be a successor cardinal, is the first step toward understanding which Easton functions can be realized as the continuum function on regular cardinals while preserving instances of λ-supercompactness.

Détail

Publié le : 2012-01-01

Zbl 1284.03234

EUDML-ID : urn:eudml:doc:286462