CSC165 SLOG week 12

This week’s lectures are all about computable function except the one on Friday. On Friday’s lecture, we did a problem on diagonals. The problems requires students to think a lot. For the computable function we learned, I don’t fully understand all of them yet, but I plan to study later since there are final exams coming and the computable function will not be in the exam.

On the other hand, I am little worried about managing time in the final exams because in the two term tests, I felt the exam time was pretty tight for me, I spent lots of time thinking questions and there will be more questions in the final exam, and proofs always take me lots of time to think. Especially in the first term test, I think I would have done much better if I had more time.

Meanwhile, we still have the last assignment that is due on next Monday. My partner and I finished most of it but there’s just the last challenging question on computable function left. This is the last full week of school, there will be only one lecture on next week, then the week after will be the final exam.

CSC165 SLOG week 11

This week we have problems without algorithms and contradictory program. There is less content than before because of the fall break. This week’s content is a litter confusing for me; I understand some of it, but there are also some parts that I am not sure. For example, the uncomputable function sounds reasonable and I understand it, but I don’t feel like I can master it right now.  

Meanwhile, I start to work on assignment 2 since assignment always takes a long time to think. For the last question in the assignment, I don’t really know how to it because it is a new type of question to me, but it says I should emulate the technique from the course notes. Also, the proof that involves limits is new to me, I am not sure on how to use n and B in those question. So I decide to read the course note in this weekend in order to have a better understanding of those questions. 

As the term approaching to its end, it’s time to begin reviewing, though there is still lots of work from different subject to do.

I just found out Celina posted some examples from lecture with her own explanation in her slog which helps me understand computability better.
http://celinasopiniononcsc165.blogspot.ca/2014/12/week-11-halt-computability-and-many.html?showComment=1417581487045#c3131525499275371659

CSC165 SLOG week 10

For the definition of big O and big Omega, I didn’t understand when it first introduced, but in the tutorial, the TA explained again and it got much clear. It was just the quiz from last week was a little bit hard and I did bad on it. So, the tutorial is pretty helpful for me. A big part of this week’s lecture is about the proof of big O and big Omega, they are understandable, but in Friday’s lecture, I felt like I spent all my time copying notes and there was no time left for me to think and learn. However, this always happens to me, I want to listen to the lecture but I worry that I will forget everything after without notes or sometimes I don’t even understand the lecture. Maybe I should change the way I listen to lecture but I don’t know how. For now, sometimes I review the notes from lecture if I have time.

On the other hand, the term test result came out; I did worse than I expected and I will take my test next week since I don’t know why I lost points in the first question and I want to see how I did in the other question so that I can figure out the questions that I didn’t get them right. I sometimes do worse in test than I expect maybe because my speed is relatively slow and I always run out of time in test, but I can’t find a good way to improve my speed. Though I guess that doing more practice probably helps, I can hardly ever achieve.

The notation in lecture said that assignment 3 will be posted during the weekend, so I plan to start it early since the questions in assignment will be hard and it will probably take lots of time to finish it. Hopefully, I can do some parts of it in the long weekend but I still have my csc108 assignment. 

A student's slog reminds me that when picking variables in proofs such as big-oh, we need to be careful of the restriction, since it may cause the whole proof to be wrong.
http://looralicsc165slog.blogspot.ca/2014/11/week-9.html?showComment=1417562128900#c4582345074674066364

CSC165 SLOG week 9

The content of this week’s lecture is not a lot, because of the term test. The term test is little bit harder than I expected, and the last question is almost the same question as the one in assignment 2. I was somehow upset about the test since I didn’t completely solve the last question out in the test. Though I did the question on assignment by myself, I just couldn’t think of how I did it, and I didn’t finish it within the time limit. I hope I can get some part marks for those questions. Also, the second question in the test was also a hard question and I didn’t finish that question. But anyways, I am still glad that I finished all my term tests.

For the assignment 2 that we just finished, 1.2 and 1.3 were pretty tough questions, I spent lots of time on them. When I checked the solution for a2, these two parts were the only two that I got different from my a2. Hopefully I will have a better mark on my a2 compared to the mark of my test.

On the other hand, this week’s tutorial cleared the maximum slice part in last week’s lecture that I didn’t understand, though I think I still can’t solve those kind of question perfectly. In Friday’s lecture, proving statements to belong to big O is relatively easier than the content in previous lectures, and I can understand all of them and it taught me a new way to prove. 

By going to other students' slog, I found out that reading over the course slides in both Danny and Larry's section helps.
http://looralicsc165slog.blogspot.ca/2014/11/week-8.html?showComment=1417560888394#c2367418532350368305

CSC165 Slog week 8

This week is a super busy week, since 165 assignment 2 and 108 assignment 2 are due next week and term test will be on Wednesday; when this two things come together, it really brings me lots of pressure and drives me crazy; and also I still have an economics test on Monday night. The assignment takes a long time to think and to do, and especially when I am stuck on a question. And right now I am struggling and stuck on Claim 1.2 and 1.3 in the assignment, they are challenging questions to prove. I really hope the test and assignments can be separated into different times, so that I can do better on both test and assignment. On the other hand, this week’s lecture is confusing, I do not understand many of the parts such as big-Oh of polynomials and non-polynomials. Also, sometimes there are lots of notes to take, and I can’t follow the lecture very well when being busy taking notes. Even though we have course notes but it does not include all the notes in class, so I think it would be helpful if the notes from class can be posted on the course page. For now, I really need to catch up on these things. This chapter is hard and proof is new to me, so it is really needed to study and I don’t have enough time, but I will try my best. Even though I don’t get a chance to go out or do anything about Halloween, Happy Halloween!!!

CSC165 Slog week 7

This week’s lecture is a little bit confusing for me. I don’t fully understand the content. Some proofs I found a way to prove it; it might be wrong because it’s different from the solution, but I don’t know why, and I just did not think in that way. Sometimes I try to do proof, but my answer is always different from the solution, and I don’t understand why I am wrong. Maybe that’s because I haven’t done a lot of proof and don’t know the how to do it in the right way and I don’t fully understand all the concepts so can’t apply them. In Friday’s lecture, the penny piles was also a little confusing, I didn’t really understand the purpose of doing it, and there were some open questions that couldn’t be solved. On the other hand, the new assignment that was just posted seems to be very hard, I didn’t understand many of the questions when I took a look at it. Also, when I did the first assignment, I felt like I spent lots of time on finding and typing symbols in computer; so I hope maybe we could change another way to write assignment. And just found out that the due date is around the CSC165 test and I got another test and assignment due in those couple days, so I need to start the assignment early, and this makes me feel lots of pressure. And proof is hard!

Also, I found out that verifying proof is the hardest thing to do since it really needs students to fully understand the whole statement rather than just doing algebra to prove a statement without thinking deeply.

When I went on other students' slog, I found a person who also has the same view as me.
http://cs1t8.blogspot.ca/2014/11/week-7.html#comment-form

Problem Solving: Folding

Folding

Fold a strip of paper. Some of the creases point vertex up, some down. Predict the sequence of ups and down for any numbers of times you carry out the folding operation.

Plan: We decided that one of us would fold the paper until we could not clearly see the pattern and the other would record, then predict the sequence of the pattern based on the patterns we have.

The Pattern we have from the first fold to the fifth.

 U

UUD

UUDUUDD

UUDUUDDUUUDDUDD

UUDUUDDUUUDDUDDUUUDUUDDDUUDDUDD

At first, we thought about creating an equation for the pattern, but we did not succeed on that. Then we thought since we folded the paper in half each time, it might have something to do with symmetric. So we started to stare at the pattern we have. As I compared the first letter to the last one, the second to the second last, and so on, I found out the pattern!

We divided the pattern into the first half, the middle and the second half.

U

UUD

UUDUUDD

UUDUUDDUUUDDUDD

UUDUUDDUUUDDUDDUUUDUUDDDUUDDUDD

The first pattern depends on the way you hold the paper, and in this exercise the first pattern would be U since we folded the right end first then unfolded the entire strip.

For the first half, just simply copy the whole previous pattern.

The middle part is always the same as the first pattern.

For the second half, reverse of the first half and change each letter to the other.

Anther way:

U

UUD

UUDUUDD

UUDUUDDUUUDDUDD

UUDUUDDUUUDDUDDUUUDUUDDDUUDDUDD

The middle part is always the same.

The letters in red are symmetrical. They copy the letter in red in the previous pattern as the first half of the pattern (only for red letter), and the second half is the reverse of the first half and it changes each letter to the other (only for red letter).

The rest in black are all in the pattern of UD.

CSC165 Slog week 6

The test result was posted this week and the class average is low 80s which surprised me. It makes me worry that will the difficulty for the next test rise. But the fact that I spent too much time on a difficult question which caused me did not have enough time for an easy question really upsets me, and it makes me realize that I need to mange my time more properly next time so that my mark would not be affected by this again. 

In the lecture of this week we continued on proof, focused on the structure of proof and also learned something new such as proving something false, trying to switch the direction to think and work and proof by cases. For this week’s lecture I understand most of it but there is just a little confusion on some slides and I think I will figure it out later. Because of the math mid-term, I had less time spent on cs, but I will spend more time studying cs after. However, I just found out that there will be an assignment 2 due at the end of October, this make me a little bit anxious because I still have another term test around that time and two other assignment from other classes.

Jacky was also struggling with proof at first, but he found a way to solve it out. Maybe I should try to practice proof in the way he suggested.
http://cs1t8.blogspot.ca/2014/10/week-6-slack.html#comment-form

CSC165 Slog week 5

In this week, I began to learn about proof started with the structure of proof and there was a mid-term on Wednesday. I didn’t do very well on the test because the time was tight, I didn’t finish the last part of the second last question which I believe I could do it if I spent couple more minutes, and did the last question wrong. Before the test, I felt lots of pressure because I was not very confident with this course since this is my first test and when doing the previous term test, I got many of the questions wrong. But I spent time working on it and figured it all out eventually; this helped me a lot on the test. On the other hand, for the proof I just learned, it seems to be fine for me and it is somehow like math. Since there was a test in this week, the content we learned is much less than the previous weeks and this gives me a chance to understand the new content more fully. Friday’s lecture was oaky for me, although I got lost in the last part.

CSC165 Slog week 4

Slog week 4

This week in csc165 I first learned about proof and the term test coming in next week made me feel somehow anxious. I feel like unprepared for the test because I haven’t done any exercise for this course and I didn’t spend enough time on it. Sometimes I feel like I've finished all the work because I don’t have any homework; however, it’s extremely important to review and preview. I planned to study for the test in weekend. 

This week conjunction, disjunction and negation were introduced. First, I found the idiom is interesting to read. Secondly, the silly English trick part is interesting but it requires to think more carefully when doing logic since the way people use "and" and "or" in daily life is little different than the way these two words are used in cs. Thirdly, the part of negating a statement by using rules is reasonable. By comparing the original statement and its negation; then translating them into English form, it can be seen that they are the opposite to each other.

On the other hand, the first assignment is due this week; I struggled with this assignment because of the same reason, the lack of exercise. But when I worked with my partner and we discussed, I felt much better and it helped me lot. At the same time, I also found out I didn’t know how to draw the Venn diagram for implication; my partner helped a bit and I do much better right now though I still need to practice more.

CSC165 Week3

Slog Week 3

This week I learned more about implication, symbols, negation, and also learned some new concepts such as bi-implication and transitivity. But I don’t fully understand the new things and therefore, I will need to spend some time on those things.  In the lecture, vacuous truth is an interesting idea that I seldom thought about before, and I have never thought of proving an idea in this way.

At the same time, the assignment 1 came out and I am currently working on this. By doing the assignment, I realized there are some shortcomings in my way of studying. First of all, I need to spend more time reviewing the things I learned after every lecture. Second, it is also necessary to preview before lectures. Most importantly, I think I need do some homework regularly because when I was doing the assignment, I found out that with the lack of daily practice, I don't feel very confident about my work and encountered many problems that I didn’t notice before. On the other hand, I believe that practicing problem-solving questions are really helpful for tests and it would enforce memorization a lot. Since there isn’t any homework in csc165, I guess I have to search some other study materials by myself. I hope I can figure out a way to study CSC165.

Problem Solving

    E is the set of employees, F is the set of female employees, and L is the set of employees earning less than 55,000:

         ∀ χ ∈, if F(χ), then L(χ).

If the implication is true, what can you deduce the following sets:

1.      F, the set of female employees?

2.      L, the set of employees earning less than 55,000?

3.      ¯F, the set of non-female employees?

4.      ¯L, the set of employees earning at least 55,000?

If you could add a new employee, what gender and salary combination would you pick in order to falsify the implication?

The implication says in all employees, if they are female, then they earn less than 55,000.

1.      Therefore, in the first set, we can deduce that female employees earn less than 55,000.

2.      The set of employees earning less than 55,000 must contain female employees, but also they there could be male employees.

3.      For non-female employees, they could either earn more or less than 55,000.

4.      In the set of employees earning at least 55,000, there could only be male employees or no employees because the implication concludes that female employees earn less than 55,000, and therefore, there would be no female employees in this set.

If I could add a new employee, I would add a female who earns at least 55,000 in order to falsify the implication. Since this is a universal claim, to falsify this claim, we need to find at least one counter example, which is the female employee who earns at least 55,000. She is female, but she does not earn less than 55,000, and the statement is false.

The universally-quantified implication previously could be written:

∀ χ ∈, F(χ) => L(χ).

Reverse the direction, and you can have the inverse of the original implication.

∀ χ ∈, L(χ) => F(χ).

What connection is there between the truth of an implication and its converse?

         The converse of the implication states that in all employees, if they earn less than 55,000, then they are female. By comparing the implication and its converse, it can be known that they both mean that:

         F => L  If they are female, they earn less than 55,000.

         L => F  If they earn less than 55,000, then they are female.

     F ≠> ¯L  If they are female, they do not earn at least 55,000, which means they do not earn more than 55,000.

        ¯L ≠> F  If they earn at least 55,000, then they are not female, because if they are female, then they earn less than 55,000.

     ¯F => ¯L  If they are male, they earn at least 55,000 because the employees who earn less than 55,000 are female.

         ¯L=> ¯F  If they earn at least 55,000, then they are male.

CSC165 SLOG week2

CSC165 seems to be a pretty challenging course for me. Despite the fact that I am still trying to get used to the new way of teaching in university, in the same time I realize the importance of understanding each part of the course. Therefore, I felt really frustrated when I fell behind in the lecture this week. So I spent more time after class trying to figure out the parts that I didn’t understand, it helped a little bit; but more importantly, the tutorial helped me solve the problem a lot because of the slower speed of speaking and with more details. Also, the CS Help Center is a great place to go when having problems unsolved, which I went this week, though I found that everyone has to bring their own laptop because the computers there do not work.

The idea of implication that I learned this week is interesting because it seems to connect with people’s thinking and inertial thinking, but also it is a difficult material to cover fully, which makes me feel much less confident and worry about it. In the week 2 lecture, symbols are used frequently and it took me time to think of the meaning of those symbols every time when I used it. This increases my time of understanding and solving problems and the chance to fall behind in the lecture, I hope it will get better as I use more those symbols.