reserve i,j,k for Nat;

theorem Th5:
  for K being commutative left_unital non empty multLoopStr holds
  the_unity_wrt the multF of K = 1.K
proof
  let K be commutative left_unital non empty multLoopStr;
  reconsider e=1.K as Element of K;
  e is_a_unity_wrt the multF of K by Th4;
  hence thesis by BINOP_1:def 8;
end;
