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
  for p being FinSequence of REAL st len p = 3 holds
  p is 3-element FinSequence of REAL
  proof
    let p being FinSequence of REAL;
    assume len p = 3;
    then p = <* p.1,p.2,p.3 *> by FINSEQ_1:45;
    hence thesis;
  end;
