theorem Th80:
for
Al being
QC-alphabet for
p being
Element of
CQC-WFF Al for
x being
bound_QC-variable of
Al for
A being non
empty set for
J being
interpretation of
Al,
A st ( for
v being
Element of
Valuations_in (
Al,
A)
for
vS,
vS1,
vS2 being
Val_Sub of
A,
Al st ( for
y being
bound_QC-variable of
Al st
y in dom vS1 holds
not
y in still_not-bound_in p ) & ( for
y being
bound_QC-variable of
Al st
y in dom vS2 holds
vS2 . y = v . y ) &
dom vS misses dom vS2 holds
(
J,
v . vS |= p iff
J,
v . ((vS +* vS1) +* vS2) |= p ) ) holds
for
v being
Element of
Valuations_in (
Al,
A)
for
vS,
vS1,
vS2 being
Val_Sub of
A,
Al st ( for
y being
bound_QC-variable of
Al st
y in dom vS1 holds
not
y in still_not-bound_in (All (x,p)) ) & ( for
y being
bound_QC-variable of
Al st
y in dom vS2 holds
vS2 . y = v . y ) &
dom vS misses dom vS2 holds
(
J,
v . vS |= All (
x,
p) iff
J,
v . ((vS +* vS1) +* vS2) |= All (
x,
p) )