digraph non_distinguishable {
	s1 -> s1 [label="a / 0"];
	s2 -> s1 [label="a / 0"];
	s3 -> s3 [label="a / 1"];

	s1 -> s3 [label="b / 0"];
	s2 -> s2 [label="b / 1"];
	s3 -> s2 [label="b / 1"];
}