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 Th38:
  |(p,p <X> q)| = 0
  proof
    thus |(p,p <X> q)| = |{p,p,q}| by EUCLID_5:def 5
                 .= 0 by EUCLID_5:31;
  end;
