theorem Th37:
  L is being_line & A in L & B in L & A <> B implies L = Line(A,B)
  proof
    assume
A1: L is being_line & A in L & B in L & A <> B;
    reconsider x1=A,x2=B as Element of REAL 2 by EUCLID:22;
    L = Line(x1,x2) by A1,EUCLID_4:10,EUCLID_4:11;
    hence thesis by Th4;
  end;
