theorem Th40: :: CQC_THE2:40

for A being QC-alphabet
for p, q being Element of CQC-WFF A
for x being bound_QC-variable of A holds
( (Ex (x,(p 'or' q))) => ((Ex (x,p)) 'or' (Ex (x,q))) is valid & ((Ex (x,p)) 'or' (Ex (x,q))) => (Ex (x,(p 'or' q))) is valid )