reserve

  k,n for Nat,
  x,y,X,Y,Z for set;

theorem
  for P1,P2 being IncProjStr st the IncProjStr of P1 = the
IncProjStr of P2 for A1 being POINT of P1, A2 being POINT of P2 st A1 = A2 for
  L1 being LINE of P1, L2 being LINE of P2 st L1 = L2 holds A1 on L1 implies A2
  on L2;
