On \sigma-weights
by
Joseph T. H. Lo
St Edmund Hall, Oxford, U.K.
Coauthors: P. M. Gartside (University of Pittsburgh), R. W. Knight (University of Oxford)

For a topological space X, we define a \sigma-base to be a collection B of open sets of X, such that every open set of X is the countable union of elements of B. The \sigma-weight of X, \sigmaw(X), is the smallest cardinal of a \sigma-base for X. We consider conditions under which \sigmaw(X) <= \aleph₁.

Topology Atlas Preprint

Date received: May 18, 2001