theorem
  F is commutative associative & F is having_a_unity implies
  F"**"(i|->(F.(d1,d2))) = F.(F"**"(i|->d1),F"**"(i|->d2))
proof
  reconsider T1 = i|->d1, T2 = i|->d2 as Element of i-tuples_on D;
  i|->(F.(d1,d2)) = F.:(T1,T2) by FINSEQOP:17;
  hence thesis by Th35;
end;
