let FMT be non empty FMT_Space_Str ; :: thesis: for x being Element of FMT
for A being Subset of FMT holds
( x in A ^Fob iff for W being Subset of FMT st W in U_FMT x holds
W meets A )

let x be Element of FMT; :: thesis: for A being Subset of FMT holds
( x in A ^Fob iff for W being Subset of FMT st W in U_FMT x holds
W meets A )

let A be Subset of FMT; :: thesis: ( x in A ^Fob iff for W being Subset of FMT st W in U_FMT x holds
W meets A )

thus ( x in A ^Fob implies for W being Subset of FMT st W in U_FMT x holds
W meets A ) :: thesis: ( ( for W being Subset of FMT st W in U_FMT x holds
W meets A ) implies x in A ^Fob )
proof
assume x in A ^Fob ; :: thesis: for W being Subset of FMT st W in U_FMT x holds
W meets A

then ex y being Element of FMT st
( y = x & ( for W being Subset of FMT st W in U_FMT y holds
W meets A ) ) ;
hence for W being Subset of FMT st W in U_FMT x holds
W meets A ; :: thesis: verum
end;
assume for W being Subset of FMT st W in U_FMT x holds
W meets A ; :: thesis: x in A ^Fob
hence x in A ^Fob ; :: thesis: verum