The influence of a small cardinal on the product of a Lindelöf space and the irrationals

Lawrence, L. Brian

doi:10.1090/S0002-9939-1990-1021211-4

The influence of a small cardinal on the product of a Lindelöf space and the irrationals
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Proc. Amer. Math. Soc. 110 (1990), 535-542 Request permission

Abstract:

It is unknown whether there is in ZFC a Lindelöf space whose product with the irrationals is nonnormal. We give some necessary conditions based on the minimum cardinality of $a{ \leq ^*}$ unbounded family in ${}^\omega \omega$.

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A normal space

for which

is not normal

73

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