Published online by Cambridge University Press: 09 April 2009
If (X, τ) is a topological space, is a family of subsets of X, then the expansion of τ by
is the topology τ(
) on X having τ ∪
as a subbase. If (X, τ) has property
, when does (X, τ(
)) have property
? In this paper we answer this question for the property
of dimension. We apply our techniques to first countability and related properties.