Abstract
A space X is sequentially separable if there is a countable D ⊂ X such that every point of X is the limit of a sequence of points from D. Neither “sequential + separable” nor “sequentially separable” implies the other. Some examples of this are presented and some conditions under which one of the two implies the other are discussed. A selective version of sequential separability is also considered.
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Bella, A., Bonanzinga, M. & Matveev, M. Sequential + separable vs sequentially separable and another variation on selective separability. centr.eur.j.math. 11, 530–538 (2013). https://doi.org/10.2478/s11533-012-0140-5
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DOI: https://doi.org/10.2478/s11533-012-0140-5