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Please Help I'm begging you. please!
Logic equations

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Please Help I'm begging you. please!

asdf1234
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Posted 11/05/09 - 01:04 PM: Subject: Please Help I'm begging you. please!	#1
I know I shouldn't do this, but please help me someone. I have an exam tomorrow on this, but I have no idea how to solve them. I spent the past 3 days studying the rules, equations, etc. and tried to solve numerous practice questions in the book but I still don't know how to approach these questions.. my prof said 5 of these seven questions will be on my exam tomorrow. At this rate I'm most certainly failing the course. Please, anybody who is good with this please help me. I will really really really appreciate it. Please save me!! 1) (p ? q) & (r ? s) ~q v ~r t ? (p & r) /? ~t 2) (p v q) ? r r ? (s & t) /? p ? t 3) p ? (q & r) ~q p v s /? p ? t 4) p /? q v ~q 5) p ? (q ? r) q ? ( r ? s) ~s /? p ? r 6) ~(p ? ~q) p ? (r v ~s) ~s /?p ? r 7) (p ? q) v (r ? s) p v ~r /? (r & ~q) ? s

rigelrover
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Posted 11/05/09 - 01:18 PM:	#2
Don't you have a calculator?
I am more interested in questions than answers; dialog than dictation. If we can reasonably believe that there is not just a breach, but a fundamentally unclosable gap between the individual mind and the ultimate nature of the reality; the primordial thing in itself, then 'true' mystery does exist.

asdf1234
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Posted 11/05/09 - 02:01 PM: Subject: umm	#3
... you can't do that with calculator. The questions are actually 1) (p -> q) & (r -> s) ~q v ~r t ? (p & r) /... ~t 2) (p v q) -> r r ->(s & t) /... p -> t 3) p -> (q & r) ~q p v s /... p -> t 4) p /... q v ~q 5) p -> (q <-> r) q -> ( r -> s) ~s /... p -> r 6) ~(p <-> ~q) p -> (r v ~s) ~s /...p -> r 7) (p -> q) v (r -> s) p v ~r /... (r & ~q) -> s

asdf1234
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Posted 11/05/09 - 02:02 PM: Subject: oops	#4
The first question mark is "->." I promise $300 to whoever can provide the answers. Edited by Incision on 11/05/09 - 05:53 PM. Reason: capitalization, punctuation

frank2010
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Posted 11/05/09 - 02:22 PM:	#5
What does the slash mean? and the dots?

Cadrache
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Posted 11/05/09 - 02:29 PM:	#6
It is not worth 300$. By us giving you the answers - how do you suppose your economy will decline? Gads... the snowball effect. Worst then the housing crash. What are those symbols? Every and all known professors give you a cheet sheet with all them lovely modus ponens and what-not. Don't get confused with the variable. Look at the signs themselves. P ^ Q (or P&Q) will follow the same modus operati as R&T or even B&W. Then finally... we can't bloody well tell you the answer to begin with. Are you looking for truth tables? Or are you merely supposed to simplify each system? Or are you supposed to simply by way of modus pollens and then find the truth table? That's likely all the help you are going to get.
"...There was a writer who asked why it was that when we find positive experiences we say that only the physical facts are real, but in negative experiences we believe that reality is subjective. He made an example of those who say that in birth only the pain is real, the joy a subjective point of view, but that in death it is the emotional loss that is the reality." - Tony Ballantyne, Recursion. _____________________________________________ Truth is want. - The internal state of matters. Truth is Need. - The external state of affairs.

rigelrover
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Posted 11/05/09 - 02:31 PM:	#7
[quote=asdf1234]... you can't do that with calculator. Are you sure? I was able to do it on mine.
I am more interested in questions than answers; dialog than dictation. If we can reasonably believe that there is not just a breach, but a fundamentally unclosable gap between the individual mind and the ultimate nature of the reality; the primordial thing in itself, then 'true' mystery does exist.

Cadrache
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Posted 11/05/09 - 03:37 PM:	#8
yawn Can you at least post you real name and Social Security number so that we don't have to bother with wasting money on hiring somebody encapable of the job?
"...There was a writer who asked why it was that when we find positive experiences we say that only the physical facts are real, but in negative experiences we believe that reality is subjective. He made an example of those who say that in birth only the pain is real, the joy a subjective point of view, but that in death it is the emotional loss that is the reality." - Tony Ballantyne, Recursion. _____________________________________________ Truth is want. - The internal state of matters. Truth is Need. - The external state of affairs.

xzJoel
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Posted 11/05/09 - 03:43 PM:	#9
asdf1234 wrote: ... you can't do that with calculator. The questions are actually 1) (p -> q) & (r -> s) ~q v ~r t ? (p & r) /... ~t I see a ? between "t" and "(p & r)". I'll pretend like the ? is "if and only if" or the biconditional. 1. \| (P > Q) & (R > S) 2. \| ~Q v ~R 3. \| T iff (P & R) Prove ~T ____________________ So let's talk. You've got to prove ~T. Where, if anywhere, does it appear in the proof? Line 3. Does it appear as a T or a ~T? As a T. What connectors are in line 3? A biconditional. How do you seperate out one of the parts of a biconditional? How do you negate one of the parts of the biconditional? With that in mind, let's see if we can prove ~(P & R). What do we have to work with? One disjunction and one conjunction that has conditionals as its conjuncts. What rules, if any, come to mind? (P > Q) & (R > S) P v R therefore? Do you have something of that form? Can you make something look like that? Is it possible to turn line 1 into something that you can work with? Do you know a rule that lets you turn (P > Q) into (~Q > ~P)? If using the above transformations and rules, you are able to get a line with (~P v ~R), what does that let you make that is useful? Answer these questions and you'll be well on your way to solving #1. If you need help, ask, but since this is a test, it wouldn't be polite of me to just give you all of the answers. _____________________ So then he left never to return. It appears like he may have meant that line 3 is T > ( P & R). This, of course, changes the analysis so far as the biconditional is concerned, but it rather simplifies the problem and permits a use of ~(P&R) to give us ~T through a much more famous rule. Edited by xzJoel on 11/05/09 - 03:50 PM
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Posted 11/05/09 - 08:24 PM:	#10
Thank you, xzJoel, for trying to help. Everyone else: shame on you. This is the logic homework subforum. It was perfectly reasonable of asdf1234 to ask for -- and expect -- constructive advice on how to solve these problems.
"The key to being a good manager is keeping the people who hate me away from those who are still undecided." --Casey Stengel

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