
theorem
  for x being object, L being Z_Lattice, L1 being Z_Sublattice of L holds
  x in L1 implies x in L
  proof
    let x be object, L be Z_Lattice, L1 be Z_Sublattice of L;
    A1: L1 is Submodule of L by ThSL1;
    assume x in L1;
    hence thesis by A1,ZMODUL01:24;
  end;
