Original Article
Kyungpook Mathematical Journal 2005; 45(4): 455-470
Published online December 23, 2005
Copyright © Kyungpook Mathematical Journal.
Variants of Compactness in Pointfree Topology
Bernhard Banaschewski1, Sung Sa Hong2
1Department of Mathematics and Statistics, McMaster University, Hamilton, L8S 4K1, Canada
2Department of Mathematics, Sogang University, Seoul 121-742, Korea
This paper introduces compactness notions for frames which are expressed in terms of the convergence of suitably specified general filters. It establishes several preservation properties for them as well as their coreflectiveness in the setting of regular frames. Further, it shows that supercompact, compact, and Lindel"of frames can be described by compactness conditions of the present form so that various familiar facts become consequences of these general results. In addition, the Prime Ideal Theorem and the Axiom of Countable Choice are proved to be equivalent to certain conditions connected with the kind of compactness considered here.}
Keywords: frame, general filter in a frame, convergence of general filter, compactness conditions, coproducts and closed quotients of frames, lax retracts of frames