The inequality |X|≤2χ(X) has been proved to be true for both the class of Lindelöf spaces (Arhangel'skii, 1969 ) and that of H-closed spaces (Dow and Porter, 1982 ), by different arguments. We present a common weakening of the Lindelöf and H-closed properties which allows us to give a unified proof of these two theorems.
|Titolo:||A useful common weakening of Lindelöf and H-closed|
|Data di pubblicazione:||2019|
|Appare nelle tipologie:||1.1 Articolo in rivista|