theorem Th42: :: AFINSQ_2:43

for n being Nat
for D being non empty set
for F being XFinSequence of D
for b being BinOp of D st n in dom F & ( b is having_a_unity or n <> 0 ) holds
b . ((b "**" (F | n)),(F . n)) = b "**" (F | (n + 1))