let Al be QC-alphabet ; for A being non empty set
for x being bound_QC-variable of Al
for v being Element of Valuations_in (Al,A)
for p being Element of Funcs ((Valuations_in (Al,A)),BOOLEAN) holds
( (FOR_ALL (x,p)) . v = TRUE iff for v1 being Element of Valuations_in (Al,A) st ( for y being bound_QC-variable of Al st x <> y holds
v1 . y = v . y ) holds
p . v1 = TRUE )
let A be non empty set ; for x being bound_QC-variable of Al
for v being Element of Valuations_in (Al,A)
for p being Element of Funcs ((Valuations_in (Al,A)),BOOLEAN) holds
( (FOR_ALL (x,p)) . v = TRUE iff for v1 being Element of Valuations_in (Al,A) st ( for y being bound_QC-variable of Al st x <> y holds
v1 . y = v . y ) holds
p . v1 = TRUE )
let x be bound_QC-variable of Al; for v being Element of Valuations_in (Al,A)
for p being Element of Funcs ((Valuations_in (Al,A)),BOOLEAN) holds
( (FOR_ALL (x,p)) . v = TRUE iff for v1 being Element of Valuations_in (Al,A) st ( for y being bound_QC-variable of Al st x <> y holds
v1 . y = v . y ) holds
p . v1 = TRUE )
let v be Element of Valuations_in (Al,A); for p being Element of Funcs ((Valuations_in (Al,A)),BOOLEAN) holds
( (FOR_ALL (x,p)) . v = TRUE iff for v1 being Element of Valuations_in (Al,A) st ( for y being bound_QC-variable of Al st x <> y holds
v1 . y = v . y ) holds
p . v1 = TRUE )
let p be Element of Funcs ((Valuations_in (Al,A)),BOOLEAN); ( (FOR_ALL (x,p)) . v = TRUE iff for v1 being Element of Valuations_in (Al,A) st ( for y being bound_QC-variable of Al st x <> y holds
v1 . y = v . y ) holds
p . v1 = TRUE )
hence
( (FOR_ALL (x,p)) . v = TRUE iff for v1 being Element of Valuations_in (Al,A) st ( for y being bound_QC-variable of Al st x <> y holds
v1 . y = v . y ) holds
p . v1 = TRUE )
by A1; verum