A countable intersection of open dense sets in a complete metric space (or locally compact Hausdorff space) is dense; equivalently, such a space is not a countable union of nowhere-dense closed sets. Baire 1899. Underlies the…
A countable intersection of open dense sets in a complete metric space (or locally compact Hausdorff space) is dense; equivalently, such a space is not a countable union of nowhere-dense closed sets. Baire 1899. Underlies the…