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;
reserve pf for FinSequence of D;
reserve PQR for Matrix of 3,F_Real;

theorem Th72:
  Line(<*pf*>,1) = pf
  proof
    1 in Seg 1 by FINSEQ_1:1;
    then Line(<*pf*>,1) = ( <*pf*> ).1 by MATRIX_0:52;
    hence thesis;
  end;
