On the double density spectra of compact spaces
摘要
The set dd(X) of densities of all dense subspaces of a topological space X is called the double density spectrum of X. In this note we present a couple of results that imply λ ∈ dd(X), provided that X is a compact Hausdorff space and λ is a cardinal satisfying certain conditions.
As a consequence of these, we prove that dd(X) = [d(X), w(X)] holds for any polyadic space X. This, in turn, implies that dd(G) = [d(G), w(G)] for any locally compact topological group G.