reserve U1,U2,U3 for Universal_Algebra,
  n,m for Nat,
  x,y,z for object,
  A,B for non empty set,
  h1 for FinSequence of [:A,B:];
reserve h1 for homogeneous quasi_total non empty PartFunc of
    (the carrier of U1)*,the carrier of U1,
  h2 for homogeneous quasi_total non empty PartFunc of
    (the carrier of U2)*,the carrier of U2;

theorem Th13:
  for p being 1-sorted-yielding FinSequence holds len Carrier p = len p
proof
  let p be 1-sorted-yielding FinSequence;
  dom Carrier p = dom p by Def13;
  hence thesis by FINSEQ_3:29;
end;
