Chang's conjecture may fail at supercompact cardinals
Résumé
We prove a revised version of Laver's indestructibility theorem which slightly improves over the classical result. An application yields the consistency of $(\kappa^+,\kappa)\notcc(\aleph_1,\aleph_0)$ when $\kappa$ is supercompact. The actual proofs show that $\omega_1$-regressive Kurepa-trees are consistent above a supercompact cardinal even though ${\rm MM}$ destroys them on all regular cardinals. This rather paradoxical fact contradicts the common intuition.
Domaines
Logique [math.LO]
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