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

theorem Th14:
  for D being non empty set, M being Matrix of D st [i,j] in
  Indices M holds M*(i,j)=(M.i).j
proof
  let D be non empty set, M be Matrix of D;
  assume [i,j] in Indices M;
  then ex p being FinSequence of D st p=M.i & M*(i,j)=p.j by MATRIX_0:def 5;
  hence thesis;
end;
