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The subspace of weak P -points of *

Salvador García-Ferreira, Y. F. Ortiz-Castillo (2015)

Commentationes Mathematicae Universitatis Carolinae

Let W be the subspace of * consisting of all weak P -points. It is not hard to see that W is a pseudocompact space. In this paper we shall prove that this space has stronger pseudocompact properties. Indeed, it is shown that W is a p -pseudocompact space for all p * .

Tightness and π-character in centered spaces

Murray Bell (1999)

Colloquium Mathematicae

We continue an investigation into centered spaces, a generalization of dyadic spaces. The presence of large Cantor cubes in centered spaces is deduced from tightness considerations. It follows that for centered spaces X, πχ(X) = t(X), and if X has uncountable tightness, then t(X) = supκ : 2 κ ⊂ X. The relationships between 9 popular cardinal functions for the class of centered spaces are justified. An example is constructed which shows, unlike the dyadic and polyadic properties, that the centered...

Two spaces homeomorphic to S e q ( p )

Jerry E. Vaughan (2001)

Commentationes Mathematicae Universitatis Carolinae

We consider the spaces called S e q ( u t ) , constructed on the set S e q of all finite sequences of natural numbers using ultrafilters u t to define the topology. For such spaces, we discuss continuity, homogeneity, and rigidity. We prove that S ( u t ) is homogeneous if and only if all the ultrafilters u t have the same Rudin-Keisler type. We proved that a space of Louveau, and in certain cases, a space of Sirota, are homeomorphic to S e q ( p ) (i.e., u t = p for all t S e q ). It follows that for a Ramsey ultrafilter p , S e q ( p ) is a topological group....

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