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morrowasted
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*philosophy majors/logicians* a little bit of help please
#14029975 - 02/26/11 11:33 AM (13 years, 7 days ago) |
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I am currently taking Symbolic Logic II. I normally am able to figure out my schoolwork, but I am stumped right now, and I was wondering if anyone else with experience could help. It is a proof in predicate logic

note that the proof is not necessarily going to be 12 lines, I just put space there to make it obvious that the bottom line is the conclusion. the only non provisional premise is line (1).
PA = provisional assumption IP = indirect proof QE = quantifier exchange EO = existential out AO = universal out
thanks in advance to anyone who can help.
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morrowasted
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Re: *philosophy majors/logicians* a little bit of help please [Re: morrowasted]
#14030339 - 02/26/11 12:52 PM (13 years, 7 days ago) |
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is this correct? i feel like it is strange to use CP so whimsically, but i cant find anything technically wrong with my method
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teknix
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Re: *philosophy majors/logicians* a little bit of help please [Re: morrowasted]
#14030727 - 02/26/11 02:25 PM (13 years, 7 days ago) |
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What does it all mean?
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morrowasted
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Re: *philosophy majors/logicians* a little bit of help please [Re: teknix]
#14030972 - 02/26/11 03:29 PM (13 years, 7 days ago) |
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it doesn't mean much of anything yet at least, not to you. it's just a bunch of variables and operators and logical inference rules
symbolic logic is similar to math (thats kind of a misleading statement, since the system of mathemetics we all know and love is basically just symbolic logic with an extremely abbreviation system of notation, but it is a helpful comparison for beginners)). you have formulas, and variables, and so forth. but in predicate logic, your variables stand for written statements instead of numerical values.
logic is about the form of your symbols, not their content. none of what you see means anything until those symbols become recognizable to you.
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deCypher



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Re: *philosophy majors/logicians* a little bit of help please [Re: morrowasted]
#14031116 - 02/26/11 03:57 PM (13 years, 7 days ago) |
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It would help if we knew what rules are allowed in this program...
-------------------- We are all in the gutter, but some of us are looking at the stars.
 
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morrowasted
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Re: *philosophy majors/logicians* a little bit of help please [Re: morrowasted]
#14031153 - 02/26/11 04:03 PM (13 years, 7 days ago) |
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The argument, written in english, would read like this:
Quote:
For any X, if X is an R or an M, then X is a D.
Therefore, for any X, if X is an R, then X is a D, and, if X is an M, then X is a D.
seems obvious. it is. but the point of logic is to prove things, because oftentimes arguments that are "obviously" convincing are completely invalid.
Quote:
It would help if we knew what rules are allowed in this program...
Any derivable rule with the exception of Universal Generalization.
I try to stick with Existential Instantiation/Out, Universal Instantiation, Quantifier Exchange, Indirect Proof, Conditional Proof, Modus Ponens, Double Negation, Contraposition, Modus Tollens, Simplification, Addition, Conjunction, DeMorgans, Arrow Connective Exchange (annotated by AR), Disjunctive Syllogism, and Hypothetical Syllogism
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teknix
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Re: *philosophy majors/logicians* a little bit of help please [Re: morrowasted]
#14031181 - 02/26/11 04:10 PM (13 years, 6 days ago) |
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Is this like Kernel level programming?
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teknix
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Re: *philosophy majors/logicians* a little bit of help please [Re: teknix]
#14031197 - 02/26/11 04:14 PM (13 years, 6 days ago) |
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So 18 is = 17?
Whats the diff between 10 and 16?
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Poid
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Re: *philosophy majors/logicians* a little bit of help please [Re: teknix]
#14031589 - 02/26/11 05:38 PM (13 years, 6 days ago) |
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Quote:
teknix said: Whats the diff between 10 and 16?
6?
-------------------- Well I try my best to be just like I am, but everybody wants you to be just like them. -- Bob Dylan  fireworks_god said:It's one thing to simply enjoy a style of life that one enjoys, but it's another thing altogether to refer to another person's choice as "wrong" or to rationalize their behavior as being pathological or resulting from some sort of inadequacy or failing so as to create a sense of superiority or separation as yet another projection of a personal fear or control issue.
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deCypher



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Re: *philosophy majors/logicians* a little bit of help please [Re: morrowasted]
#14032484 - 02/26/11 08:14 PM (13 years, 6 days ago) |
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How'd you get from 6 to 7? Isn't the negation of (P -> Q) (P & ~Q), not (P -> ~Q)?
-------------------- We are all in the gutter, but some of us are looking at the stars.
 
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ShroomScape
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Re: *philosophy majors/logicians* a little bit of help please [Re: Poid]
#14032745 - 02/26/11 09:08 PM (13 years, 6 days ago) |
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Quote:
Poid said:
Quote:
teknix said: Whats the diff between 10 and 16?
6?
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morrowasted
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Re: *philosophy majors/logicians* a little bit of help please [Re: deCypher]
#14033831 - 02/26/11 11:56 PM (13 years, 6 days ago) |
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Quote:
deCypher said: How'd you get from 6 to 7? Isn't the negation of (P -> Q) (P & ~Q), not (P -> ~Q)?
actually, yes, I think you you are correct, the Arrow Exchange rule is only applicable to the main connective in a given formula. but if you'll notice on the dependency list, line 7 (the erroneous line) is never referenced in the remainder of the proof
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morrowasted
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Re: *philosophy majors/logicians* a little bit of help please [Re: teknix]
#14033858 - 02/27/11 12:01 AM (13 years, 6 days ago) |
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Quote:
teknix said: Is this like Kernel level programming?
yes
but I am not advanced enough in my knowledge of computer technology to do anything like that yet
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deCypher



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Re: *philosophy majors/logicians* a little bit of help please [Re: morrowasted]
#14033873 - 02/27/11 12:04 AM (13 years, 6 days ago) |
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Okay... how'd you get from 12 to 13?
-------------------- We are all in the gutter, but some of us are looking at the stars.
 
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morrowasted
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Re: *philosophy majors/logicians* a little bit of help please [Re: deCypher]
#14033912 - 02/27/11 12:15 AM (13 years, 6 days ago) |
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Disjunctive Syllogism on lines 6 and 12
i)~(Ra -> Da) v ~(Ma -> Da) ii)~~(Ra -> Da) _______________________ iii)|:. ~(Ma -> Da)
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deCypher



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Re: *philosophy majors/logicians* a little bit of help please [Re: morrowasted]
#14033927 - 02/27/11 12:20 AM (13 years, 6 days ago) |
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Word... don't see any problems with your proof then.
-------------------- We are all in the gutter, but some of us are looking at the stars.
 
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andrewss
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Re: *philosophy majors/logicians* a little bit of help please [Re: deCypher]
#14033957 - 02/27/11 12:27 AM (13 years, 6 days ago) |
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symbolic logic... fuck dat shiz
-------------------- Jesus loves you.
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teknix
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Re: *philosophy majors/logicians* a little bit of help please [Re: ShroomScape]
#14034741 - 02/27/11 08:03 AM (13 years, 6 days ago) |
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Quote:
ShroomScape said:
Quote:
Poid said:
Quote:
teknix said: Whats the diff between 10 and 16?
6?

Haha, wouldn't it be -6?
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morrowasted
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Re: *philosophy majors/logicians* a little bit of help please [Re: andrewss]
#14035296 - 02/27/11 11:08 AM (13 years, 6 days ago) |
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Quote:
andrewss said: symbolic logic... fuck dat shiz 
i love it
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Re: *philosophy majors/logicians* a little bit of help please [Re: teknix]
#14035870 - 02/27/11 01:03 PM (13 years, 6 days ago) |
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Quote:
teknix said:
Quote:
ShroomScape said:
Quote:
Poid said:
Quote:
teknix said: Whats the diff between 10 and 16?
6?

Haha, wouldn't it be -6?
--------------------
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