Abstract
This paper establishes the consistency of a countably complete, uniform, ℵ1-dense ideal on ℵ2. As a corollary, it is consistent that there exists a uniform ultrafilterD on ω2 such that |ω ω21 D|=ω1. A general “transfer” result establishes the consistency of countably complete uniform ideal K on ω2 such thatP(ω2)/K≅P(ω1)/ {countable sets}.
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Foreman, M. An ℵ1-dense ideal on ℵ2 . Israel J. Math. 108, 253–290 (1998). https://doi.org/10.1007/BF02783051
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DOI: https://doi.org/10.1007/BF02783051