let T be non empty TopSpace; :: thesis: [#] T is F_sigma

reconsider F = {([#] T)} as Subset-Family of T ;

( F is closed & [#] T = union F ) by Th20, ZFMISC_1:25;

hence [#] T is F_sigma ; :: thesis: verum

reconsider F = {([#] T)} as Subset-Family of T ;

( F is closed & [#] T = union F ) by Th20, ZFMISC_1:25;

hence [#] T is F_sigma ; :: thesis: verum