 reserve L for non empty LattStr;
 reserve v100,v102,v2,v1,v0,v3,v101 for Element of L;
 reserve L for WA_Lattice;
 reserve x,y,z,u for Element of L;

theorem Lemacik1:
  x [= z & y [= z implies x "\/" y [= z
  proof
    assume x [= z & y [= z; then
    x "/\" z = x & y "/\" z = y by LATTICES:4;
    hence thesis by defW33;
  end;
