Blowing up the power of a singular cardinal
Moti Gitik
Abstract
Suppose that kappa is a singular cardinal of cofinality omega and GCH holds. Assume that for every n<omega the set of alphas with o(alpha)>= alpha+n is unbounded in kappa.Then there is a cardinal preserving extension satisfying 2kappa=kappa++ and GCH below kappa. By a result of W. Mitchell and the author the assumptions are optimal.
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