meet F c= D

proof

A1: meet F c= union F by Th2;
let x be object ; :: according to TARSKI:def 3 :: thesis: ( not x in meet F or x in D )
assume x in meet F ; :: thesis: x in D
then x in union F by A1;
hence x in D ; :: thesis: verum

end;

hence meet F is Subset of D ; :: thesis: verum