Slog for Week 4

    In week 4, the professor Larry Zhang went over bi-implication, transitivity, and mixed quantifiers. At the beginning of the lecture, he began the lecture with explanation of why p => q equals to ㄱp  or q: because two statement have the same truth table. His explanation made me understood since I had not understood why those statements are equivalent. By knowing the concept, I have become to be flexible in many other questions related to it. Now I am familiar with De Morgan's Law, implication law, and so on.

   Also before I listened the lecture on Tuesday, I was not sure why the order of universal quantification and existential quantification makes difference, but now I have the idea why switching x and y, which are quantified, makes different statements. For example, the statements of 'For every women, there is a man who is her soul mate,' and 'There is a man, every woman is his soul mate.' have exactly different meaning by only switching the place of x and y. 

  Even though I understand most of lecture, there was the part I can hardly understood. In mixed quantifiers, the professor went over two mathematical examples, but I could not follow since I have no idea from the beginning of the example. I expected to get the ideas of similar questions from the tutorial, but we just did problems about bi-implication that I already had plenty of ideas.

   I might going to try to find the similar examples from the past tests that the professor put on the lecture slide, and to be able to solve them with many practices.