Article ID | Journal | Published Year | Pages | File Type |
---|---|---|---|---|
4658274 | Topology and its Applications | 2015 | 9 Pages |
Abstract
We consider the question: Can a normal dense subspace of a product of separable metric spaces contain a closed discrete subset whose cardinality is greater than c? We prove that if Y is a normal dense convex subspace of a product of real lines, then e(Y)â¤c, but every product â{Mα:α<2Ï} of non-trivial separable metric spaces contains a perfectly normal dense subspace Z, so the answer is “yes” since for such a subspace we have 2Ïâ¤2|Z| and, by Hajnal-Juhász inequality, |Z|â¤2e(Z). (The subspace Z which we construct actually has a closed discrete subset of cardinality Ï.)
Related Topics
Physical Sciences and Engineering
Mathematics
Geometry and Topology
Authors
D.P. Baturov,