Abstract
Lindelof numbers of sets Z subset of beta(lambda) \ lambda are examined in G delta-topologies (and in G mu- topologies). The results are in a close connection to measurable and mu-strongly compact cardinal numbers.
Those numbers are characterized by means of extensions of weakly complete filters, by tau-compactness of sets of certain complete ultrafilters and by Lindelof numbers of the set of uniform ultrafilters in G mu-topologies. Some known results about mu-strongly compact cardinals are reproved using set-theoretical methods. (c) 2023 Elsevier B.V.
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