theorem Th44:
  G is independent implies 'not' Ex(Ex(a,A,G),B,G) = All('not' Ex( a,B,G),A,G)
proof
  assume G is independent;
  then 'not' Ex(Ex(a,A,G),B,G) = 'not' Ex(Ex(a,B,G),A,G) by PARTIT_2:16;
  hence thesis by BVFUNC_2:19;
end;
