Normality and
AbstractThe main result of this paper is that if κ is not a weakly Mahlo cardinal, then the following two conditions are equivalent:1. is κ+-complete.2. is a prenormal ideal.Our result is a generalization of an announcement made in [Z]. We say that is selective iff for every -function f: κ → κ there is a set X ∈ such that f∣(κ − X) is one-to-one. Our theorem provides a positive partial answer to a question of B. Wȩglorz from [BTW, p. 90], viz.: is every selective ideal with κ+-complete, isomorphic to a normal ideal?The theorem is also true for fine ideals on [λ]<κ for any κ ≤ λ, i.e. if κ is not a weakly Mahlo cardinal then the Boolean algebra is λ+-complete iff is a prenormal ideal (in the sense of [λ/<κ).
2019 ◽
Vol 27
(3)
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pp. 259-278
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2013 ◽
Vol 30
(2)
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pp. 277-295
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1970 ◽
Vol 2
(3)
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pp. 401-413
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1966 ◽
Vol 24
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pp. 118-119
1988 ◽
Vol 46
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pp. 394-395
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