theorem
  All('not' Ex(a,A,G),B,G) '<' Ex(Ex('not' 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 Th46;
end;
