Week 7: Reviewing Proofs + algorithm running time+ asymptotic notation

This week, I have started doing some general proofs from the practice questions, finally figured out how to conclude the ideas I've got about proofs so far.

After doing couple proof questions, there are some "tricks"  have been generated:

- the structure helps and matters!
Always start from constructing a general structure (how are you gonna prove, what methods would you use,...)before actually doing the proof.

- consider using NEGATION INTRODUCTION when you know that there is an exception
- pick a reasonable number when seeing existential quantifier
- ...



reviewed in lectures:

- split by cases
- negation introduction
- conjunction introduction
- disjunction introduction
- implication introduction (direct/ contrapositive)
- equivalence introduction

Speaking of algorithms, Larry introduced two sorting algorithm: bubble sort and merge sort. With larger input, the advantage of merge over bubble becomes larger. One important concept is that the running time is not actually the time, it's the number of steps to execute the algorithm. However, I did not understand how Larry applied the concept of running time to the big-Oh during lecture until I checked Timothy's slog. I like the way he applies the course content to real-life experiments(e.g.running sorting code on his potato and toaster):
http://timothylock.me/sLOG/2014/10/25/week-7-consulting-the-sorting-hat/

My listening of English is not good, so I did not catch all the explanations. Therefore, Timothy's slog is a saver to me because he is good at understanding the materials and converting the materials into his words. I've seen some other slogs online, none of them explains as clearly and interestingly as he does.