Type: Article

Ordering Frechet-Urysohn filters

García-Ferreira, S.; Rivera-Gomez, J. E;

Abstract:

A free filter F on the natural numbers omega is called Frechet-Urysohn (FU) if the space omega boolean OR {F} with just one accumulation point is a Frechet-Urysohn space, where the neighborhoods of F are of the form {F} boolean OR F for F is an element of T. The Frechet filter and the countable FAN-filter are the known examples of FU-filters, but we know that there are 2(c)-many pairwise non-equivalent FU-filters. In this article, we shall order this kind of filters by using the Rudin-Keisler order of filters.