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Fibers of continuous real-valued functions on psi-spaces

机译:psi空间上连续实值函数的光纤

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We consider continuous real-valued functions with domain either a psi-space (studied by S. Mrowka, J. Isbell, and others) or a generalized psi-space introduced by A. Dow and J. Vaughan. A cardinal kappa >= omega is called a rich cardinal provided for every infinite, maximal almost disjoint family M of countably infinite subsets of kappa (MADF) and for every continuous f : psi(kappa, M) -> R defined on the associated space psi = psi (kappa.M) there exists r is an element of R such that vertical bar f(-1)(r)vertical bar = vertical bar psi vertical bar. Dow and Vaughan proved that omega is a rich cardinal if and only if a = c, where a is the smallest cardinality of a MADF on omega. We prove that a = c if and only if, for all omega <= kappa <= c, kappa is a rich cardinal, if and only if for every n < omega, omega(n), is a rich cardinal. We prove every kappa > c is rich using a set-theoretic hypothesis weaker than GCH. (C) 2015 Published by Elsevier B.V.
机译:我们考虑具有psi空间(由S. Mrowka,J。Isbell等研究)或由A. Dow和J. Vaughan引入的广义psi空间的具有域的连续实值函数。一个基数kappa> =ω被称为丰富基数,它是由kappa的无数无限子集(MADF)的每个无限,最大几乎不相交的族M以及在相关空间上定义的每个连续f:psi(kappa,M)-> R所提供的psi = psi(kM),存在r是R的一个元素,使得竖线f(-1)(r)竖线=竖线psi竖线。陶氏和沃恩证明,当且仅当a = c时,欧米茄才是丰富的基数,其中a是欧米茄MADF的最小基数。我们证明,当且仅当对于所有Ω<= kappa <= c,kappa是一个丰富的基数,并且当且仅当对于每一个n c都丰富。 (C)2015由Elsevier B.V.发布

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