reserve D for non empty set,
  i,j,k for Nat,
  n,m for Nat,
  r for Real,
  e for real-valued FinSequence;

theorem Th31:
  for i for R being Element of i-tuples_on REAL holds mlt(i|->1,R) = R
proof
  let i;
  let R be Element of i-tuples_on REAL;
  thus mlt(i|->1,R) = 1*R by RVSUM_1:63
    .= R by RVSUM_1:52;
end;
