theorem
  Product(n |-> a) = a |^ n
proof
  defpred P[Nat] means Product($1 |-> a) = a |^ $1;
A1: for n being Nat st P[n] holds P[n+1] by Lm2;
A2: P[0] by Lm1;
  for n being Nat holds P[n] from NAT_1:sch 2(A2,A1);
  hence thesis;
end;
