for p1, p2, q1, q2 being Point of (TOP-REAL 2) st ( p1 `1 = p2 `1 or p1 `2 = p2 `2 ) & LSeg (q1,q2) c= LSeg (p1,p2) & not q1 `1 = q2 `1 holds
q1 `2 = q2 `2