
theorem
  for L being Z_Lattice, L1, L2 being Z_Sublattice of L holds
  0.L1 in L2
  proof
    let L be Z_Lattice, L1, L2 be Z_Sublattice of L;
    L1 is Submodule of L & L2 is Submodule of L by ThSL1;
    hence thesis by ZMODUL01:34;
  end;
