Proof done.

So, proof is done. It was challenging problem. Firstly, I thought it would take just a few minutes along with a few lines to write down the proof, but finally I spent 3 hours to prove it. Now its done.

Progress on problem

Solution has been found and claim is written down (for me this is the hardest part). So tomorrow I want to do the proof and the problem will be solved!

Starting Solving a problem

I started to solve the problem on page:
https://wwwcgi.cdf.toronto.edu/~heap/cgi-bin/Solvent/
wiki.pl?Problem_Solving_Home_Page/SumProducts
under name Persik (page called Persik Solution) and the problem is about sums. Hope, I will progress fast.

Last week coming

Last week starts tomorrow. Just one more test left, no problem sets and no assignments, and this means I have to study only with a book and lecture notes, with no actual problems and I don't like it. I like theory and practice....I hope, test won't be very difficult. I am starting to study for it much earlier then before, I start...now! So I have a week to look through the material. I see no difficulties in languages/regular expressions for me. Moreover, I am looking forward to solving one of the problems (as mentioned on courSe LOG handout).

A3!

Oh, I don't believe, I have done A3. I still have some questions. In Q2, where you are offered to prove/disprove 4 statements, could I use the fact mentioned in the book without proving it or I have to prove it? : (1+0)* = (1*0*)*. Because in this case R2 = R4: R2 = (0 + (10*1))* = (0*(10*1)*)* = R4. And then only one statement can be proved and another will be proven automatically.
To be on the safe side, I decided to prove both.

Something

We are studying regular expressions both in CSC236 and CSC207 simultaniously, so it's much easier to understand something new, when you do theoretical and practical stuff together. I did not that bad in the test#2, but I hope I'll do much better in test#3. By the way, I still can not understand, why do we really need to study in so much detail all this theoretical material (I mean the whole course in general, all this proofs and little things. Will we need them ever? :), but, since I am too young and don't understand a lot of things, I am not disappointed that much :)

Before T2

Test2 is fastly approaching, but due to so much tests and assignments during last 2 weeks, I am not sure if remember everything for the test. If the proof of correctness of recursive program is not that hard(probably because we did one for A2), but the same proof for program with loops is not good for me. I still do not completely understand what is the loop invariant and how to prove that the loop terminates (here comes the book to help me, unfortunately). I have much time on Thursday, so I'll try to do my best.