Second Blog, Friday September 26, 2014

 What’s something new you learned this week in class?

This week we learned about conjunctions, disjunctions, and negations.

A conjunction is when two or more things occur exist at once. For example, “I ate an apple and a banana”.

A disjunction is when at least one of two or more statements is true. Using the example “I ate an apple or a banana” does not exactly capture what a disjunction is. “Or” in how it is typically used in English is usually exclusive. “I ate an apple or a banana” is not inclusive – it will usually be interpreted as saying that I ate either an apple or a banana, one or the other.

A negation is used to indicate a thing is not true. For example “I did not eat an apple”.

 What’s something that challenged or frustrated you this week?

Understanding the difference between “or” used in English and “or” used in this class was confusing at first. It made more sense after the tutorial.

How condent do you feel about material covered this week?

Overall, I’m not very confident in how to interpret and write in “computer speak”. I find that it’s harder to interpret what something says than it is to translate a sentence into math/computer language.

How did your tutorial/test/assignment go this week?

The tutorials really helped, I had made a lot of mistakes in the homework assignments. I do not think I got full marks for the quiz, though. I still need to practice.

Creating and solving some problems.

To make this a little more fun, I’m going to try to come up with and solve examples with zombie themes.

Let M be the set of all Monsters. Z(x) are zombies.

Write out “All zombies are monsters”

∀ x ∈ M, Z(x).

Let B(x) be bunnies. Bunnies are clearly not monsters. Write out “No bunnies are monsters”.

∀ x ∈ M, ¬ B(x).

Let G(x) be ghosts. Write out “All ghosts are monsters”

∀ x ∈ M, G(x).

Write out “All ghosts and zombies are monsters”

(∀ x ∈ M, Z(x)) ∧ (∀ x ∈ M, G(x))

Fred or John, or both, may now be zombies. At least one of them was bitten. Let F(x) be Fred and J(x) be John. Express that one or both is now a monster.

(∃ x ∈ M, F(x)) ∨ (∃ x ∈ M, J(x))

These examples express all of the mathematical symbols we learned in class and how they can be used.

First Blog – Friday September 19, 2014

How did the tutorials go?

I found that the tutorial went well. We went over the problems that were assigned, and I fixed a few mistakes I made in the problems. The quiz was easier than I thought it would be.

How does this course relate to other classes? 

I’ve found that csc165 and csc108 have some overlapping material, and I think it’s helped to be in both of these classes. Symbols like quantifiers and symbols used in relating sets to one another have also appeared in my math classes.

What did you learn this week, what did you find challenging? 

I’ve never had any experience with Python or other programming languages before. In the first week, I found that the lecture slides titled “Computer language => Human Language” very confusing.  It just looked like a bunch of letters and numbers. It was also pretty intimidating to see that a lot of my classmates seemed to know the answers to the examples the professor was going through. But now, I recognize that it’s python code.

For example:

def q4(S1, S2):

’’’Return whether S1 and S2 have

intersection

’’’

for x in S1:

if x in S2 : return True

return False

I now know that “def” signifies that below we will define what the function “q4” will mean, and what it will return. In this case, we are telling python to return “true” if S1 and S2 intersect, but to return “false” if they don’t intersect. I realize that this is probably really basic stuff, but it’s something that looked completely alien 2 weeks ago.

What did you find interesting? 

I really liked the problem the “streetcar dilemma” the professor posted.

Week 2 Difficulties

Although I recognized a lot of what was being talked about in the lecture in week 2, I found it challenging to understand. I’ve had to take my time going over the lecture slides. The “if P then Q” statements are pretty straightforward, but unpacking a statement like “∀x ∈C,W(x)=> ∃y∈C,P(x,y)” takes some time.

“∀x ∈C,W(x)  ⇒ ∃y∈C,P(x,y)” means:

“A course is worthy only when it is a prerequisite of some course.”, but I find I have to slowly break it down symbol by symbol to fully understand it.

∀ – for all or for every

∈ “is an element of”

C refers to a course

W refers to being worthy, or worthiness

⇒ means “implies” or “if/then”

∃ means “there exists”

P refers to prerequisite

So, altogether, I see it saying something like this:

For every x that is a course (C), it is worthy only if (⇒) there exists y that is a course, that is a prerequisite (P) of x that is y.

Or more simply, “A course is only worth if there exists a course that is prerequisite for that course”.

It still takes me a while to do this. Overall, I feel pretty confident in the material I’ve learned, but I need to practice more to be faster at interpreting what is said.