# Need Some Help with SD

1. Nov 4, 2007

### Kwiatkowski18

My teacher threw us a couple of questions on SD that I know hardly anything about. The first one one to come up with correct answers receives an additional 10% on our next paper. I would really like to answer them all myself, but I don't have the information about SD to do them as I have never taken a Phil course regarding Logics. So please, if anyone could solve these for me, that would be wicked.

Legend: >=horeshoe = is triplebar

1. Prove that the following derivability claim holds in SD.
{(t > a) & (~t > b), a > ~l} deriviation: l > b

2. SHow that the following set of sentences is inconsistent in SD.
{(a v ~c) > ~b), ~b = (q & ~q), ~c v a}

3. Show that the members of the following pair of sentences are equivalent in SD.
a = b ~a = ~b

4. Show that the following argument is valid in SD.
(b & (e v g))
(b & g) = h
(h > f) & ~e
____________
c > f

Thanks guys/girls.

2. Nov 4, 2007

### Staff: Mentor

Do not post the same topic in more than one forum. We do not supply answers to schoolwork here. If you are having trouble solving a problem and show what you have done so far and where you are stuck, someone might give you suggestions on what you might do to try to solve it yourself.

3. Nov 4, 2007

### Kwiatkowski18

Sorry about the double post. But it isnt technically for marks as it isnt in our curriculum. It's just for bonus marks if someone can come up with it. The teacher says he doesnt care how we came up with it, he just wants to see if anyone could come up with it.

4. Nov 4, 2007

### Staff: Mentor

That's fine, but you still need to show what you've tried so far. Or at least explain where you are stuck so someone has some starting point to work with you on the problems.

I'm sure when your teacher said he doesn't care how you come up with the answers, he didn't maen to just ask someone for the answers, I think he hoped you would would attempt to reason it out.

5. Nov 4, 2007

### Kwiatkowski18

Obviously, without any prior knowledge on the subject, he wouldn't have expected us to get our own answers. He sent us on a treasure hunt. Some kids are going to other professors in the morning but I want to beat them all and hopefully get the answers tonight from here so I can lock up the extra percent on my next paper.

6. Nov 4, 2007

### Staff: Mentor

Well, good luck then.

I had an insane history teacher in the 10th grade. We never opened our book the entire year. Each class he'd talk about his vacuum cleaner or his health or the cost of car repairs. Once a week our assignment was to have a full page of writing on any subject. The first time I chose a subject and did a lot of research and it was a great paper. He told us to place the papers on our desk and he walked down the isle and wrote either "A" or "F" without reading them. He wrote "F" on my paper and started to walk off and I told him he didn't even read it. He said I left the last two lines blank, so it wasn't a full page. From then on I just turned in a full page of words that said nothing and got straight A's. I even got bonus points for extra assignments like "draw a fence in Africa". I drew a fence and a giraffe standing next to it.

The point is, I didn't learn anything that year.

Last edited: Nov 4, 2007
7. Nov 4, 2007

Thank you.