S-spaces can exist under MA
An S-space is a hereditarily separable not Lindelöf regular space. Various examples of S-spaces were constructed using some combinatorial consequences of the axiom of constructibility. It was not known whether S-spaces can exist under Martin's axiom. The author proves, in a remarkable way, that ConZF\(C\to Con(ZFC+Martin's axiom+\exists S\)-space).
scientific article; zbMATH DE number 3846430
scientific article