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  • Productively Lindelöf spaces of countable tightness
    Medini, Andrea ; Zdomskyy, Lyubomyr, 1983-
    Michael asked whether every productively Lindelöf space is powerfully Lindelöf. Building of work of Alster and De la Vega, assuming the Continuum Hypothesis, we show that every productively Lindelöf ... space of countable tightness is powerfully Lindelöf. This strengthens a result of Tall and Tsaban. The same methods also yield new proofs of results of Arkhangel'skii and Buzyakova. Furthermore, assuming the Continuum Hypothesis, we show that a productively Lindelöf space ▫$X$▫ is powerfully Lindelöf if every open cover of ▫$X^\omega$▫ admits a point-continuum refinement consisting of basic open sets. This strengthens a result of Burton and Tall. Finally, we show that separation axioms are not relevant to Michael's question: if there exists a counterexample (possibly not even ▫$\mathsf{T}_0$▫), then there exists a regular (actually, zero-dimensional) counterexample.
    Source: Houston journal of mathematics. - ISSN 0362-1588 (Vol. 43, no. 4, 2017, str. 1263-1272)
    Type of material - article, component part ; adult, serious
    Publish date - 2017
    Language - english
    COBISS.SI-ID - 18179673

source: Houston journal of mathematics. - ISSN 0362-1588 (Vol. 43, no. 4, 2017, str. 1263-1272)
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