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Set-theoretic constructions of nonshrinking open covers
Authors:Amer Bešlagić  Mary Ellen Rudin
Institution:Mathematics Department, University of Wisconsin-Madison, Madison, WI 53706, USA
Abstract:A family {Mα|α?A} is a shrinking of a cover {Oα|α?A} of a topological space if {Mα|α?A} also covers and Mα?Oα for all α?A.?++ implies that there is a normal space such that every increasing open cover of it has a clopen shrinking but there is an open cover having no closed shrinking.? implies that there is a P-space (i.e. a space having a normal product with every metric space), which has an increasing open cover having no closed shrinking. This space is used in 17] to show that any space which has a normal product with every P-space is metrizable.
Keywords:54D18  54A35  03E45
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