[拓樸]幾題拓樸空間(Topological Space)
想請教幾題有關拓樸空間基本的証明
1.prove that every countable first-countable space is second countable
2.Is it true that every aeparable first-countable space is second countable?
prove or find counterexample
3.Prove that if X has the property that every open cover of X that consists
of basic open sets has a countable subcover ,then X is Lindelof
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