reserve L for non empty LattStr;
reserve v3,v101,v100,v102,v103,v2,v1,v0 for Element of L;

theorem Lemacik00:
  for v0,v1 being Element of QLTLattice1 st v1 = 0 holds
    v0 "/\" v1 = v1
  proof
    let v0,v1 be Element of QLTLattice1;
    assume
A1: v1 = 0;
    per cases;
    suppose v0 = v1;
      hence thesis by QLTEx1Def;
    end;
    suppose v0 <> v1;
      hence thesis by A1,QLTEx1Def;
    end;
  end;
