CSC165H1 SLOG2 BY MINGYU LIU

Mingyu Liu @ CSC165H1 SLOG2

In the lecture of this week, Professor Danny Heap continues to teach us about language of math which mainly concentrates on conjunction, disjunction, negation and Demorgan's laws. i will start with the first topic which the Professor has covered in the lecture. Conjunction is news to me; therefore, my primary aim is to understand it by knowing its definition which is combining two statements by claiming they are both true. For instance, there are for two statements which are both true. The first statement says that car 'X' is red and the second statement has a saying which is car 'X' is a Ferrari; therefore, the conjunction of these two statements is called Car 'X' is a Ferrari and red. This is a case which is told by using human language, but using mathematical language is far more different to express. in human language,  we use 'and' to combine two statements while we use symbol '^' to combine statements in Math. This means that 'statement 1' and 'statement 2' is the same as 'statement 1' ^ 'statement 2'.

After the introduction of conjunction, professor also talks about disjunction which we use 'v' to describe it in Math and 'or' in human language. i understand it in a different way which is that treating disjunction as a set of 'union'. For example, 'Statement 1' V 'Statement 2' equals to 'Statement 1' U 'Statement 2'. Negation is what I grasp well in this week's lecture which using 'not' and the symbol '-\' to prove statements that are negative. For example,'Not all red cars are Ferrari'can be written in this way: '-\(Axec,R(x)=>F(x)).

Professor also teaches us some useful tips which are changing 'not all... ' In 'There is one that is not... 'and 'there does not exist... 'to 'all...are not'. These tips are useful because we can understand what the question requires us to do both quickly and efficiently; therefore, the way of solving the problem is just change the word simply.

There are no difficulties of this week's lecture, but the exercise of TUT is a little bit difficult for me. For instance, question number two of exercise which makes me encounter some problems which is that I initially write all the answers to get true, but the correct answers are different. After the teaching of TA, I find out during TUT.

In conclusion,lectures and tutorials of this week continue the topic of how to change human language into mathematical expression. Professor does superb work to help me understand the lecture and TA  helps me to resolve the problems of exercise with patience. Next week, I will continue to collaborate hard in both lecture and tutorial.

Second slog
Mingyu Liu