Thursday, November 13, 2008

Week 10 - Nov 13, 2008

We got Test 2 back today and I got exactly what I thought I would get. Not bad but not as good as Test 1. The important thing is that I know what my mistakes are and I also know how to avoid them. That's all I have to say about Test 2.

In the lecture this week we saw DFSA (Deterministic Finite State Automata). Drawing states and arrows seems fun! 

I really liked that fact that you can represent a language using a DFSA quite easily. We saw how hard it was to express (L1 \intersection L2) using a regular expression but we came up with the DFSA for it fairly easily. L1 was the language that contained all binary strings with an even number of zeroes and L2 the language that contained all binary strings with an odd number of ones. 

We did not see a proof of the correctness of the DFSA but it's something we will see next week. The professor felt that it was too late for that proof and that it was better suited for the first hour of next week's lecture. Couldn't agree more!



2 comments:

Danny Heap said...

There are other languages that are easier to express with a regular expression than with a DFSA. Try L(1*0)*

Christos said...

Hm...I now see why they compliment each other so well hehehe. I was not able to find a DFSA for this regex.