
theorem Th21:
  for V being RealUnitarySpace, I being Basis of V, v being VECTOR
  of V holds v in Lin(I)
proof
  let V be RealUnitarySpace;
  let I be Basis of V;
  let v be VECTOR of V;
  v in the UNITSTR of V by STRUCT_0:def 5;
  hence thesis by Def2;
end;
