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Just finished Test 3. Unfortunately, I left it with some regret, as I ran out of time while writing again. I knew exaclty what I needed to write, if only I had 2 more minutes...

The typos on the cartesian product question led to quite some delay and confusion. I had to rerun through the process several times and didn't have enough time to check my final answer. I believe I wouldn't have ran out of time if there weren't any typo.

I always disliked it when ppl kept writing when the time's up, and I never ever did it myself. But I *might* (leaving it a bit ambiguous for obvious reasons) have been guilty of it this time.... I came in a bit late, some ppl didn't have the typo in their tests (doesn't justify anything, as there are also others' tests that had the typos).
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I went to Danny's office hr. My understanding of the pumping lemma and its application in the last post is incorrect. I'm glad I went.
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As I mentioned in my first post, I thought I disliked the theory part of CSC because it was of little value to my practical mindset, and that I was weak in the skills needed in theory. Also in my first post, I mentioned the possibility that this course might change my mind. Indeed it has.

This class, in combination with significant changes in my work ethic and overall responsibility, changed my mind to a very large extent.
Working with classmates also helped change my mind: I worked with fellow students who struggled.
I also worked with brilliant fellow students whom I'm sure are significantly smarter than I am. They also struggled (albeit for a shorter time, and understands almost instantaneously with explanation) on some topics. Interestingly, it is somewhat comforting and motivating to know that brilliant people also struggle to understand some topics sometimes.

The way Danny structures and teaches the topic is just fantastic - it really helped narrow the "gap" between my intuitive thought process and the rigorous theory topics. This was never done so well in any other course I've taken that had theory components.

I think that, besides providing us with greater understanding of the rigorous topics themselves, from the way this course is taught I've also learnt approaches that would allow me to work better with other theory topics -> a very valuable and well executed course.

I look forward to csc300 with Danny next term.
And since I've decided to go to Shanghai where my father is working, to spend time with my family this summer instead of taking summer courses, I hope I can catch another Heap course in the fall, intro to database hopefully.

Pumping Lemma, CFGs

The end of the term is very close. Time passes way too fast...

I realized that the pumping lemma could be difficult so I did some pre-reading before the lecture. Unfortunately, I still don't really get it after the lecture. The test is this friday, so I'm going to be going over it right after I finish this.

Unfortunately I think I'm also rather unclear, or have a lack of intuitive understanding of the regularity of a language. Is it generally any language that requires some "memory" to represent as a regex or FSA?

Context-free Grammars are interesting.
It's obvious that we've only seen the tip of the iceberg in this area, and I'm quite interested in how the theory can be extended and applied in practical usage. Unfortunately (or maybe fortunately,) I won't have to get too deep into this, as I'm not planning to take compilers or programming language courses.

***edit
After looking at the course notes and lecture notes. I find the lecture notes much clearer intuitively. But the course notes has great stuff too. With the combination of going through both I *think* I understand how proof of regularity by the pumping lemma works now.

For languages which have some pumping length for which the pumping lemma holds for all strings in the language, it is regular.
For languages which have arbitrarily large pumping lengths, and so no single pumping length works for all strings in the language, the language is not regular.

I hope that understanding is correct.

Test 1

Test 1 didn't go as well as I expected.
Even though i had the right induction insights, I had lots of mistakes in the write up. With one question completely missing the base cases. I also got marks off for not stating the conclusion... I thought the conclusion was implicitly obvious if we stated P(n) clearly... The course notes are like this too iirc.

The test ended with me not having enough time to finish write ups.
I think I spent too much time thinking of the insight, and had to rush through the write up. I Need more practice.

Had to miss class this Monday to complete a music essay. Apparently I missed the lecture about preconditions, and PS4 is on preconditions. I have no idea what it's about, and lecture notes aren't posted yet. so I must attend the evening lecture this week.

Unwinding

My blog was apparently flagged by a spam filtering system implemented by blogger.com... They say the system is inherently fuzzy... I wonder if it uses fuzzy logic and whether I will learn about it in later CSC theory courses.

I really like the way Danny first discussed and showed how the sum of the Fibonacci sequence up to n is equal to F(n+2) - 1. Then in the next lecture, showed us how to unwind T(n) of zpf(n), where the same sequence of Fibonacci sums showed up. The way he structures the course is really helping me learn more than I would have otherwise.

I am still feeling unclear about how to get from unwinding to a closed form, how and if unwinding helps in proofs. I was feeling the same about PSI, PCI, PWO as well, but now I feel quite comfortable with them. I'm sure with a bit of time and practice I will feel comfortable and clear about it

Written the first term test today. It was not too bad, but I wish I had time to finish the subset question... I believe I was on the right track . If I had 10 more minutes I might have finished a correct proof. I suppose I spent more time than I should have on the other questions, which are pretty straightforward.

In response to Danny's comment on my test structure concern post: I thought the test was structured quite well and fairly. Although personally I felt that I spent more time looking for insight than I'd have been comfortable with, and possibly more time than Danny intended. Not so used to doing the problems with such a short time constraint. All the practice I had in a1 and problem sets have days-long time constraints. I will be keeping that in mind while I do problems from now on, and perhaps not taking such a leisurely pace.