let Al be QC-alphabet ; :: thesis: for x being bound_QC-variable of Al
for A being non empty set
for J being interpretation of Al,A
for v being Element of Valuations_in (Al,A)
for S being Element of CQC-Sub-WFF Al
for xSQ being second_Q_comp of [S,x] holds
( ( for a being Element of A holds J,(v . (NEx_Val (v,S,x,xSQ))) . (x | a) |= S ) iff for a being Element of A holds J,(v . (NEx_Val (v,S,x,xSQ))) . (x | a) |= S `1 )
let x be bound_QC-variable of Al; :: thesis: for A being non empty set
for J being interpretation of Al,A
for v being Element of Valuations_in (Al,A)
for S being Element of CQC-Sub-WFF Al
for xSQ being second_Q_comp of [S,x] holds
( ( for a being Element of A holds J,(v . (NEx_Val (v,S,x,xSQ))) . (x | a) |= S ) iff for a being Element of A holds J,(v . (NEx_Val (v,S,x,xSQ))) . (x | a) |= S `1 )
let A be non empty set ; :: thesis: for J being interpretation of Al,A
for v being Element of Valuations_in (Al,A)
for S being Element of CQC-Sub-WFF Al
for xSQ being second_Q_comp of [S,x] holds
( ( for a being Element of A holds J,(v . (NEx_Val (v,S,x,xSQ))) . (x | a) |= S ) iff for a being Element of A holds J,(v . (NEx_Val (v,S,x,xSQ))) . (x | a) |= S `1 )
let J be interpretation of Al,A; :: thesis: for v being Element of Valuations_in (Al,A)
for S being Element of CQC-Sub-WFF Al
for xSQ being second_Q_comp of [S,x] holds
( ( for a being Element of A holds J,(v . (NEx_Val (v,S,x,xSQ))) . (x | a) |= S ) iff for a being Element of A holds J,(v . (NEx_Val (v,S,x,xSQ))) . (x | a) |= S `1 )
let v be Element of Valuations_in (Al,A); :: thesis: for S being Element of CQC-Sub-WFF Al
for xSQ being second_Q_comp of [S,x] holds
( ( for a being Element of A holds J,(v . (NEx_Val (v,S,x,xSQ))) . (x | a) |= S ) iff for a being Element of A holds J,(v . (NEx_Val (v,S,x,xSQ))) . (x | a) |= S `1 )
let S be Element of CQC-Sub-WFF Al; :: thesis: for xSQ being second_Q_comp of [S,x] holds
( ( for a being Element of A holds J,(v . (NEx_Val (v,S,x,xSQ))) . (x | a) |= S ) iff for a being Element of A holds J,(v . (NEx_Val (v,S,x,xSQ))) . (x | a) |= S `1 )
let xSQ be second_Q_comp of [S,x]; :: thesis: ( ( for a being Element of A holds J,(v . (NEx_Val (v,S,x,xSQ))) . (x | a) |= S ) iff for a being Element of A holds J,(v . (NEx_Val (v,S,x,xSQ))) . (x | a) |= S `1 )
thus ( ( for a being Element of A holds J,(v . (NEx_Val (v,S,x,xSQ))) . (x | a) |= S ) implies for a being Element of A holds J,(v . (NEx_Val (v,S,x,xSQ))) . (x | a) |= S `1 ) :: thesis: ( ( for a being Element of A holds J,(v . (NEx_Val (v,S,x,xSQ))) . (x | a) |= S `1 ) implies for a being Element of A holds J,(v . (NEx_Val (v,S,x,xSQ))) . (x | a) |= S )

proof

assume A1: for a being Element of A holds J,(v . (NEx_Val (v,S,x,xSQ))) . (x | a) |= S ; :: thesis: for a being Element of A holds J,(v . (NEx_Val (v,S,x,xSQ))) . (x | a) |= S `1
let a be Element of A; :: thesis: J,(v . (NEx_Val (v,S,x,xSQ))) . (x | a) |= S `1
( J,(v . (NEx_Val (v,S,x,xSQ))) . (x | a) |= S iff J,(v . (NEx_Val (v,S,x,xSQ))) . (x | a) |= S `1 ) by Def2;
hence J,(v . (NEx_Val (v,S,x,xSQ))) . (x | a) |= S `1 by A1; :: thesis: verum

end;

thus ( ( for a being Element of A holds J,(v . (NEx_Val (v,S,x,xSQ))) . (x | a) |= S `1 ) implies for a being Element of A holds J,(v . (NEx_Val (v,S,x,xSQ))) . (x | a) |= S ) :: thesis: verum

proof

assume A2: for a being Element of A holds J,(v . (NEx_Val (v,S,x,xSQ))) . (x | a) |= S `1 ; :: thesis: for a being Element of A holds J,(v . (NEx_Val (v,S,x,xSQ))) . (x | a) |= S
let a be Element of A; :: thesis: J,(v . (NEx_Val (v,S,x,xSQ))) . (x | a) |= S
( J,(v . (NEx_Val (v,S,x,xSQ))) . (x | a) |= S iff J,(v . (NEx_Val (v,S,x,xSQ))) . (x | a) |= S `1 ) by Def2;
hence J,(v . (NEx_Val (v,S,x,xSQ))) . (x | a) |= S by A2; :: thesis: verum

end;