Week XI

The week is the last week for the problem set. And because this is the last one I expected a hard question on the problem set. But it wasn't actually. The question was : Prove that L, the set of binary strings of odd length, equals L(((0+1)(0+1))*(0+1)). Before trying to prove directly, I took a time to read lecture notes and discuss with my friends who were also doing this. I knew that the L will always have strings of odd length but I did not realize that I needed to prove this with two directions where set of binary strings of odd length is in L or L in the set of binary strings of odd length. (I visited TA's to comfirm the answer) I did not know why I need two directions but the TA showed me why. It sounded clear, reasonable and obvious.

The lecture was about NFSAs. Since I am very close to the end of the classes of this term, many assignments, tests are waiting for me. Because I need to cover them, honestly I really had not enough time to look up the lecture slides. The materials for this week seem to be very different from previous ones. I better go study for 236 too.