How weak is weak extent ?
نویسنده
چکیده
We show that the extent of a Tychonoff space of countable weak extent can be arbitrary big. The extent of X is e(X) = sup{|F | : F ⊂ X is closed and discrete} while we(X) = min{τ : for every open cover U of X there is A ⊂ X such that |A| ≤ τ and St(A,U) = X} is the weak extent of X (also called the star-Lindelöf number of X). Also we show that the extent of a normal space with countable weak extent is not greater than c.
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