1 00:00:00,000 --> 00:00:02,000 Let's do some simple tests. 2 00:00:02,000 --> 00:00:06,000 We want to be able to get things like 1, 2, 3, 4 3 00:00:06,000 --> 00:00:09,000 and also 12-34. 4 00:00:09,000 --> 00:00:11,000 Let's try the first one. 5 00:00:11,000 --> 00:00:15,000 1, 2, 3, 4, we win. 6 00:00:15,000 --> 00:00:17,000 Oh, no problem there. 7 00:00:17,000 --> 00:00:20,000 How about this one, 12-34? 8 00:00:20,000 --> 00:00:25,000 Well, 1, 2--I can't take the hyphen here. 9 00:00:25,000 --> 00:00:29,000 But I could take this epsilon transition for free and then take the hyphen. 10 00:00:29,000 --> 00:00:31,000 That sounds good. 11 00:00:31,000 --> 00:00:34,000 Now I'm in state 4, and I see a 3. 12 00:00:34,000 --> 00:00:39,000 So probably there should be some sort of digit label on this edge. 13 00:00:39,000 --> 00:00:42,000 3, 4, and then back here, and I accept. 14 00:00:42,000 --> 00:00:46,000 Just to check our work, let's do something a little more complicated. 15 00:00:46,000 --> 00:00:51,000 1, 2, 3, hyphen, 3, 4. 16 00:00:51,000 --> 00:00:55,000 Free, free again, 17 00:00:55,000 --> 00:00:59,000 hyphen, 5, 6, free again, accepted. 18 00:00:59,000 --> 99:59:59,999 Excellent.