up:: Lattice Let be a Distributive and Limited lattice. Given , we seek to prove that, to any such that and implies that . We have that 1) Therefore, , by the Partial Ordering induces by the lattice. 2) Therefore, . Thus, , and every point in has a unique complement. References Notas para um Curso de Física-Matemática, João Carlos Alves Barata. Cap. 02