Some non-multiplicative properties are -invariant
Vladimir Vladimirovich Tkachuk (1997)
Commentationes Mathematicae Universitatis Carolinae
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A cardinal function (or a property ) is called -invariant if for any Tychonoff spaces and with and linearly homeomorphic we have (or the space has () iff ). We prove that the hereditary Lindelöf number is -invariant as well as that there are models of in which hereditary separability is -invariant.