Chainability and Hemmingsen's Theorem

Taras Banakh, L'viv National University
Paul Bankston, Marquette University
Brian Raines, Baylor University
Wim Ruitenburg, Marquette University

Topology and its Applications, Vol. 153, No. 14 (August 1, 2006): 2462-2468. DOI.

Abstract

On the surface, the definitions of chainability and Lebesgue covering dimension ⩽1 are quite similar as covering properties. Using the ultracoproduct construction for compact Hausdorff spaces, we explore the assertion that the similarity is only skin deep. In the case of dimension, there is a theorem of E. Hemmingsen that gives us a first-order lattice-theoretic characterization. We show that no such characterization is possible for chainability, by proving that if κis any infinite cardinal and