theorem
  All('not' Ex(a,A,G),B,G) '<' Ex('not' Ex(a,B,G),A,G)
proof
  'not' Ex(Ex(a,A,G),B,G) = All('not' Ex(a,A,G),B,G) by BVFUNC_2:19;
  hence thesis by Th43;
end;
