defpred S1[ Element of QC-WFF F1()] means ( $1 is Element of CQC-WFF F1() implies P1[$1] );
A2: for p being Element of QC-WFF F1() st S1[p] holds
S1[ 'not' p]
proof
let p be Element of QC-WFF F1(); :: thesis: ( S1[p] implies S1[ 'not' p] )
assume A3: S1[p] ; :: thesis: S1[ 'not' p]
assume 'not' p is Element of CQC-WFF F1() ; :: thesis: P1[ 'not' p]
then p is Element of CQC-WFF F1() by Th8;
hence P1[ 'not' p] by A1, A3; :: thesis: verum
end;
A4: for p, q being Element of QC-WFF F1() st S1[p] & S1[q] holds
S1[p '&' q]
proof
let p, q be Element of QC-WFF F1(); :: thesis: ( S1[p] & S1[q] implies S1[p '&' q] )
assume A5: ( S1[p] & S1[q] ) ; :: thesis: S1[p '&' q]
assume p '&' q is Element of CQC-WFF F1() ; :: thesis: P1[p '&' q]
then ( p is Element of CQC-WFF F1() & q is Element of CQC-WFF F1() ) by Th9;
hence P1[p '&' q] by A1, A5; :: thesis: verum
end;
A6: for k being Nat
for P being QC-pred_symbol of k,F1()
for l being QC-variable_list of k,F1() holds S1[P ! l]
proof
let k be Nat; :: thesis: for P being QC-pred_symbol of k,F1()
for l being QC-variable_list of k,F1() holds S1[P ! l]

let P be QC-pred_symbol of k,F1(); :: thesis: for l being QC-variable_list of k,F1() holds S1[P ! l]
let l be QC-variable_list of k,F1(); :: thesis: S1[P ! l]
assume A7: P ! l is Element of CQC-WFF F1() ; :: thesis: P1[P ! l]
reconsider k = k as Nat ;
reconsider l = l as QC-variable_list of k,F1() ;
A8: { (l . j) where j is Nat : ( 1 <= j & j <= len l & l . j in fixed_QC-variables F1() ) } = {} by Th7, A7;
{ (l . i) where i is Nat : ( 1 <= i & i <= len l & l . i in free_QC-variables F1() ) } = {} by A7, Th7;
then l is CQC-variable_list of k,F1() by A8, Th5;
hence P1[P ! l] by A1; :: thesis: verum
end;
A9: for x being bound_QC-variable of F1()
for p being Element of QC-WFF F1() st S1[p] holds
S1[ All (x,p)]
proof
let x be bound_QC-variable of F1(); :: thesis: for p being Element of QC-WFF F1() st S1[p] holds
S1[ All (x,p)]

let p be Element of QC-WFF F1(); :: thesis: ( S1[p] implies S1[ All (x,p)] )
assume A10: S1[p] ; :: thesis: S1[ All (x,p)]
assume All (x,p) is Element of CQC-WFF F1() ; :: thesis: P1[ All (x,p)]
then p is Element of CQC-WFF F1() by Th13;
hence P1[ All (x,p)] by A1, A10; :: thesis: verum
end;
A11: S1[ VERUM F1()] by A1;
for p being Element of QC-WFF F1() holds S1[p] from QC_LANG1:sch 1(A6, A11, A2, A4, A9);
hence for r being Element of CQC-WFF F1() holds P1[r] ; :: thesis: verum