2014年9月26日星期五

Slog for Week Sept. 21

  •  What’s new for this week?


This week we are going further with the topic negation and the application of conjunction and disjunction (‘and’ and ‘or’). Besides, other concepts about tautology, satifability and unsatisfiability are introduced in our class.


  •  Challenge



As I’m reading the commutative, associative and distributive approach of logic (PPT the last second slide), I’m wondering is statement (Q V┎ Q) a true statement or not? Besides, I’m still confusing why the statement P ∧ (Q ∨ ┐Q) is equivalent to P? It means P, and  Q or not Q. If (Q V┎ Q) is a true statement, then I think P ∧ (Q ∨ ┐Q) should be interpreted as P and Q or P and not Q. Why isn’t it?

2014年9月18日星期四

Slog for Week Sept. 14

-What’s something new I learned this week?

    This week we learned some concepts about existential claims, contrapositive and converse of statements, but mainly focus on implication of statements. Through this week’s classes, I was trained to easily understand a given statement and its implication as well.

-Challenge

In Wednesday’s class, we were going further on the topic of implication, converse and contrapositive. I'm still confused about the question on the slide, under the subtitle Numerical Example:


For the first given situation, if n is a multiple of 4, why the converse doesn't give us any information? The first sentence of this question has already defined P(n) is n and Q(n) is n^2. So, for the converse, we start at the Q(n) first, if n is multiple of 4 (such that 4t for t is a subset of N), then we can know Q(n) must be a multiple of 4 because Q(n) = n^2 = (4t)^2 = 16t^2, which indicates that Q(n) is true and P(n) is true as well. However, in the class professor Heap told us to consider the case of 2, but I think this case is impossible for this situation because if n = 2, then it is not a multiple of 4, which is contradicting with the given condition and seems illogical. These are all the reasons why I stuck on this question for a long time.


-Tutorial

    The tutorial exercise for this week is mainly focus on implication. It is not very challenging for me, but I think we had wasted lots of time on discussing some very silly questions during the tutorial time. However, the exercise gives me an opportunity to practice the knowledge I learned from class and I think it is very necessary. I also found that drawing a Vane Graph is a efficient way to understand the implication of a statement.