theorem Th26: :: HEYTING1:26

for A being set
for a being Element of DISJOINT_PAIRS A
for u, w being Element of (NormForm A) st ( for b being Element of DISJOINT_PAIRS A st b in u holds
b \/ a in DISJOINT_PAIRS A ) & u "/\" ((Atom A) . a) [= w holds
(Atom A) . a [= (StrongImpl A) . (u,w)