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Small u(kappa) at singular kappa with compactness at kappa++

Publication at Faculty of Arts |
2021

Abstract

We show that the tree property, stationary reflection and the failure of approachability at kappa(++) are consistent with u(kappa) = kappa(+) < 2(kappa), where. is a singular strong limit cardinal with the countable or uncountable cofinality. As a by-product, we show that if lambda is a regular cardinal, then stationary reflection at lambda(+) is indestructible under all lambda-cc forcings (out of general interest, we also state a related result for the preservation of club stationary reflection).