What is the contrapositive of this statement

wanderlust
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What is the contrapositive of this statement

Postby wanderlust » Wed Dec 01, 2010 2:06 pm

A-->B+C
Thanks!!

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icouldbuyu
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Re: What is the contrapositive of this statement

Postby icouldbuyu » Wed Dec 01, 2010 2:08 pm

wanderlust wrote:A-->B+C
Thanks!!

not b or not c--->not a

musicfor18
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Re: What is the contrapositive of this statement

Postby musicfor18 » Wed Dec 01, 2010 2:08 pm

wanderlust wrote:A-->B+C
Thanks!!


Contrapositive:

If not BOTH B and C, not A.

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Ginj
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Re: What is the contrapositive of this statement

Postby Ginj » Wed Dec 01, 2010 2:09 pm

icouldbuyu wrote:
wanderlust wrote:A-->B+C
Thanks!!

not b or not c--->not a


This one.

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TommyK
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Re: What is the contrapositive of this statement

Postby TommyK » Wed Dec 01, 2010 2:20 pm

.
Last edited by TommyK on Wed Dec 01, 2010 4:00 pm, edited 1 time in total.

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ScottRiqui
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Re: What is the contrapositive of this statement

Postby ScottRiqui » Wed Dec 01, 2010 2:29 pm

I think both answers given so far are equivalent, since

~(B AND C) == (~B OR ~C)

Arlington
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Re: What is the contrapositive of this statement

Postby Arlington » Wed Dec 01, 2010 2:31 pm

Yep, they are logically equal.

wanderlust
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Re: What is the contrapositive of this statement

Postby wanderlust » Wed Dec 01, 2010 2:40 pm

ScottRiqui wrote:I think both answers given so far are equivalent, since

~(B AND C) == (~B OR ~C)


but ~(B AND C) =/=~B and ~C

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ScottRiqui
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Re: What is the contrapositive of this statement

Postby ScottRiqui » Wed Dec 01, 2010 2:49 pm

wanderlust wrote:
ScottRiqui wrote:I think both answers given so far are equivalent, since

~(B AND C) == (~B OR ~C)


but ~(B AND C) =/=~B and ~C



I guess it depends on how you convert musicfor18's text (If not BOTH B and C) into symbols.

I read it as ~(B AND C), rather than (~B AND ~C).

To me, the "BOTH" qualifier means that B and C go together in the parentheses with an AND, and that the NOT notation applies to the entire parenthetical statement.

SchopenhauerFTW
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Re: What is the contrapositive of this statement

Postby SchopenhauerFTW » Wed Dec 01, 2010 2:55 pm

Original: A --> B+C

Contrapositive: ~B or ~C --> ~A


If B is absent but C is there, then A is absent. If B is there but C is absent, then A is absent. If both B and C are absent, then A is absent. I wouldn't write ~B and ~C --> ~A because all it takes is for either B or C to be absent to have A be absent.

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robotclubmember
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Re: What is the contrapositive of this statement

Postby robotclubmember » Wed Dec 01, 2010 3:39 pm

SchopenhauerFTW wrote:Original: A --> B+C

Contrapositive: ~B or ~C --> ~A


If B is absent but C is there, then A is absent. If B is there but C is absent, then A is absent. If both B and C are absent, then A is absent. I wouldn't write ~B and ~C --> ~A because all it takes is for either B or C to be absent to have A be absent.


Ignore everything else you've seen up to now and just focus on this, as it is actually correct. Only half of the other people's replies won't fuck you over on test day, lol.

thegarciab0y
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Re: What is the contrapositive of this statement

Postby thegarciab0y » Wed Dec 01, 2010 3:53 pm

SchopenhauerFTW wrote:Original: A --> B+C

Contrapositive: ~B or ~C --> ~A


If B is absent but C is there, then A is absent. If B is there but C is absent, then A is absent. If both B and C are absent, then A is absent. I wouldn't write ~B and ~C --> ~A because all it takes is for either B or C to be absent to have A be absent.


I'm glad somebody got it correct. LGB and/or conditional statements, look it up.

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icouldbuyu
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Re: What is the contrapositive of this statement

Postby icouldbuyu » Wed Dec 01, 2010 3:58 pm

musicfor18 wrote:
wanderlust wrote:A-->B+C
Thanks!!


Contrapositive:

If not BOTH B and C, not A.



No offense, but how did you get a 167?

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homestyle28
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Re: What is the contrapositive of this statement

Postby homestyle28 » Wed Dec 01, 2010 3:59 pm

DeMorgan's Law FTW!

~(A&B) ::~A v ~B
~(AvB) ::~A & ~B

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NYC_7911
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Re: What is the contrapositive of this statement

Postby NYC_7911 » Wed Dec 01, 2010 4:02 pm

icouldbuyu wrote:
musicfor18 wrote:
wanderlust wrote:A-->B+C
Thanks!!


Contrapositive:

If not BOTH B and C, not A.



No offense, but how did you get a 167?


Huh? As noted above, he (or she) isn't wrong. It's just worded differently. Not B or not C is the same as "not both."

tsutsik
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Re: What is the contrapositive of this statement

Postby tsutsik » Wed Dec 01, 2010 4:07 pm

icouldbuyu wrote:
musicfor18 wrote:
wanderlust wrote:A-->B+C
Thanks!!


Contrapositive:

If not BOTH B and C, not A.



No offense, but how did you get a 167?


As was already pointed out, the answer isn't wrong. The natural way to read 'If not BOTH B and C, not A' is with the negation having wide scope in the antecedent: ~(B & C) --> ~A.

That's the right answer.

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robotclubmember
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Re: What is the contrapositive of this statement

Postby robotclubmember » Wed Dec 01, 2010 5:29 pm

tsutsik wrote:
icouldbuyu wrote:
musicfor18 wrote:
wanderlust wrote:A-->B+C
Thanks!!


Contrapositive:

If not BOTH B and C, not A.



No offense, but how did you get a 167?


As was already pointed out, the answer isn't wrong. The natural way to read 'If not BOTH B and C, not A' is with the negation having wide scope in the antecedent: ~(B & C) --> ~A.

That's the right answer.


Agreed, but it's still a very trippy way to say it. Most books won't say it this way, because even if people at the 90th percentile will understand it, it's a mindfuck for people under the 90th percentile.

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JazzOne
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Re: What is the contrapositive of this statement

Postby JazzOne » Wed Dec 01, 2010 8:33 pm

icouldbuyu wrote:
musicfor18 wrote:
wanderlust wrote:A-->B+C
Thanks!!


Contrapositive:

If not BOTH B and C, not A.



No offense, but how did you get a 167?

No offense, but how can you be so oblivious?

musicfor18
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Re: What is the contrapositive of this statement

Postby musicfor18 » Wed Dec 01, 2010 8:45 pm

My answer, although completely correct, is probably not as well worded as the other. Basically, though, if either B or C is absent, A is absent.

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moopness
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Re: What is the contrapositive of this statement

Postby moopness » Wed Dec 01, 2010 8:59 pm

JazzOne wrote:
icouldbuyu wrote:
musicfor18 wrote:
wanderlust wrote:A-->B+C
Thanks!!


Contrapositive:

If not BOTH B and C, not A.



No offense, but how did you get a 167?

No offense, but how can you be so oblivious?

benito
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Re: What is the contrapositive of this statement

Postby benito » Thu Dec 02, 2010 1:30 am

I love it when someone says something as condescending as "how did you get a 167" based on information they are mistaken on themselves......there was nothing wrong at all with person's explanation at all, clearly earned their 167

pressplay
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Re: What is the contrapositive of this statement

Postby pressplay » Thu Dec 02, 2010 2:12 am

Wow. The first reply was adequate. The rest was pure entertainment. :)

dakatz
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Re: What is the contrapositive of this statement

Postby dakatz » Thu Dec 02, 2010 2:17 am

Truly amazing that an incredibly simple question which was fully answered in the 1st response needs 22 responses and unnecessary namecalling.

Brock2010
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Re: What is the contrapositive of this statement

Postby Brock2010 » Thu Dec 02, 2010 2:22 am

dakatz wrote:Truly amazing that an incredibly simple question which was fully answered in the 1st response needs 22 responses and unnecessary namecalling.


+ One hundred thousand trillion

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D. H2Oman
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Re: What is the contrapositive of this statement

Postby D. H2Oman » Thu Dec 02, 2010 2:28 am

If not B and C ----> A




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