reserve Y for non empty set,
  a, b for Function of Y,BOOLEAN,
  G for Subset of PARTITIONS(Y),
  A, B for a_partition of Y;

theorem
  All(Ex('not' a,A,G),B,G) '<' Ex(Ex('not' a,B,G),A,G)
proof
  'not' Ex(All(a,A,G),B,G) = All(Ex('not' a,A,G),B,G) by Th20;
  hence thesis by Th13;
end;
