reserve a,b,c,d,e,f for Real,
        k,m for Nat,
        D for non empty set,
        V for non trivial RealLinearSpace,
        u,v,w for Element of V,
        p,q,r for Element of ProjectiveSpace(V);
reserve o,p,q,r,s,t for Point of TOP-REAL 3,
        M for Matrix of 3,F_Real;

theorem
  |{p,q,0.TOP-REAL 3}| = 0
  proof
    |{p,q,0.TOP-REAL 3}| = |(p, q <X> 0.TOP-REAL 3)| by EUCLID_5:def 5
                        .= |(p,0.TOP-REAL 3)| by Th42;
    hence thesis by EUCLID_2:32;
  end;
