defpred S1[ set ] means P1[$1 `1 ,$1 `2 ];
deffunc H1( set ) -> set = F5(($1 `1),($1 `2));
A3: F2() = { [o,H1(o)] where o is Element of [:F1(),F1():] : S1[o] }
proof
thus F2() c= { [o,F5((o `1),(o `2))] where o is Element of [:F1(),F1():] : P1[o `1 ,o `2 ] } :: according to XBOOLE_0:def 10 :: thesis: { [o,H1(o)] where o is Element of [:F1(),F1():] : S1[o] } c= F2()
proof
let y be object ; :: according to TARSKI:def 3 :: thesis: ( not y in F2() or y in { [o,F5((o `1),(o `2))] where o is Element of [:F1(),F1():] : P1[o `1 ,o `2 ] } )
assume y in F2() ; :: thesis: y in { [o,F5((o `1),(o `2))] where o is Element of [:F1(),F1():] : P1[o `1 ,o `2 ] }
then consider o1, o2 being Element of F1() such that
A4: y = [[o1,o2],F5(o1,o2)] and
A5: P1[o1,o2] by A1;
reconsider p = [o1,o2] as Element of [:F1(),F1():] by ZFMISC_1:87;
A6: p `1 = o1 ;
p `2 = o2 ;
hence y in { [o,F5((o `1),(o `2))] where o is Element of [:F1(),F1():] : P1[o `1 ,o `2 ] } by A4, A5, A6; :: thesis: verum
end;
let y be object ; :: according to TARSKI:def 3 :: thesis: ( not y in { [o,H1(o)] where o is Element of [:F1(),F1():] : S1[o] } or y in F2() )
assume y in { [o,F5((o `1),(o `2))] where o is Element of [:F1(),F1():] : P1[o `1 ,o `2 ] } ; :: thesis: y in F2()
then consider o being Element of [:F1(),F1():] such that
A7: y = [o,F5((o `1),(o `2))] and
A8: P1[o `1 ,o `2 ] ;
reconsider o1 = o `1 , o2 = o `2 as Element of F1() by MCART_1:10;
o = [o1,o2] by MCART_1:21;
hence y in F2() by A1, A7, A8; :: thesis: verum
end;
reconsider x = [F3(),F4()] as Element of [:F1(),F1():] by ZFMISC_1:87;
A9: S1[x] by A2;
thus F2() . (F3(),F4()) = F2() . x
.= H1(x) from ALTCAT_2:sch 3(A3, A9)
.= F5(F3(),F4()) ; :: thesis: verum