8,465 research outputs found

    Woodin for strong compactness cardinals

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    We give the definition of Woodin for strong compactness cardinals, the Woodinised version of strong compactness, and we prove an analogue of Magidor's identity crisis theorem for the first strongly compact cardinal.Comment: 20 pages, fixed proof of Theorem 4.1, minor corrections and addition

    Indiscernible Sequences for Extenders, and the Singular Cardinal Hypothesis

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    We prove several results giving lower bounds for the large cardinal strength of a failure of the singular cardinal hypothesis. The main result is the following theorem: Theorem: Suppose κ\kappa is a singular strong limit cardinal and 2κ>=λ2^\kappa >= \lambda where λ\lambda is not the successor of a cardinal of cofinality at most κ\kappa. (i) If \cofinality(\kappa)>\gw then o(κ)≥λo(\kappa)\ge\lambda. (ii) If \cofinality(\kappa)=\gw then either o(κ)≥λo(\kappa)\ge\lambda or \set{\ga:K\sat o(\ga)\ge\ga^{+n}} is cofinal in κ\kappa for each n\in\gw. In order to prove this theorem we give a detailed analysis of the sequences of indiscernibles which come from applying the covering lemma to nonoverlapping sequences of extenders
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