exercise 4.9 tut501 answers

Morning. Also pasted in MyUnisa

I have a problem with exercise 4.9 answers from tut501. Maybe my Weiner sentences are different. See below.
1. (Tet(a) & Small(a)) | (Cube(b) & ~Cube(b))
2. Cube(a) & (~Cube(a) | ~Small(a)) & Small(a)
3. Larger(a, b) & (Larger(a, a) | ~Larger(a, b))
4. a # b & ~LeftOf(a, b) & ~RightOf(a, b) & ~FrontOf(a, b) & ~BackOf(a, b)
5. LeftOf(a, b) & LeftOf(b, c) & LeftOf(c, d)
6. Larger(a, b) & Larger(b, c) & Larger(c, a)
7. Between(a, b, c) & LeftOf(a, b) & LeftOf(b, c)
8. ~[(Cube(a) | ~Small(a)) & (Cube(a) | ~Medium(a))] & Cube(a)
9. ~[Dodec(b) & Larger(b, c)] & [Medium(b) | Tet(b)]
10. ~[FrontOf(a, b) | ~LeftOf(b, c)] & Between(b, c, a)

If I paste these into Boole, my answers are for TT-possible
1. Yes
2. No
3. Yes
4. Yes
5. Yes
6. Yes
7. Yes
8. No
9. Yes
10. Yes

In tut501 6 and 7 are not the same answers, but the logic is the same. So how can the answers for TT-possible be different?

HELLO.

Is all that are taking this module still living? Even if just.

I'm alive...barely...this subject is probably the hardest of all my subjects this year... still busy with question 2.2 and 2.3 of assignment 2. But if anyone has any hints/help/nudges to get me to the correct answer I'd be super grateful

Sorry I can't help with your problem Kiolb...

I am also struggling terribly with questions 2.2 and 2.3 of Assignment 2.Why has the due date of assignment 2 been brought forward?
It was initially 7 June, then on myUnisa it was brought forward to 6 June...then, when i checked today, it's actually now due for 5 June (which is tomorrow).
I feel like maybe I am just going to leave questions 2.2 and 2.3 out... but then again it's worth 22 marks altogether... that's like almost 50% of the assignment.

Ok, so I've done questions 2.1 and 2.3.
I found 2.3 quite a bit easier than 2.2 which I'm still stuck on.

Can't seem to figure out how to get A -> ~B

Annoying.

Check page 165. It gives you the proof for de morgan, which helped me tremendously with Q2.
Also look at page 49 of Tut 501.

how to get A -> ~B
assume B, then use 2 and 3 to introduce a contradiction.

Hope that helps. Spent two weeks on this assignment.

Cobus Neethling

Q 2.2
I can get from A -> ~B, but battling from ~B -> A

The other questions are done.

Found a solution from ~B -> A

Read pg 160 LPL
Prove A from premise 1

Do as Cobus said. Proof done.

No matter how hard I try, I just cannot get my head around formal proofs. Informal proofs I can do eyes shut, or explain why it's true, but just structuring them kills me. Anybody got a suggestion? Q1 + Q3 were 1..2..3, but Q2, all of them were x(

I resorted to doing as many of the exercises in the textbook as I could. Until it clicked. Then I went back to the assignment. I used the hints and solutions I downloaded from the website to help me. It made a big difference. I will definitely do the same for the next assignment.

Cobus Neethling