theorem :: ZF_REFLE:20

for W being Universe
for L being DOMAIN-Sequence of W st omega in W & ( for a, b being Ordinal of W st a in b holds
L . a c= L . b ) & ( for a being Ordinal of W st a <> {} & a is limit_ordinal holds
L . a = Union (L | a) ) holds
for H being ZF-formula ex phi being Ordinal-Sequence of W st
( phi is increasing & phi is continuous & ( for a being Ordinal of W st phi . a = a & {} <> a holds
for f being Function of VAR,(L . a) holds
( Union L,(Union L) ! f |= H iff L . a,f |= H ) ) )