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'every'

V

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'every'
« on: May 24, 2005, 10:32:44 AM »
Prep 45 Game 3, Albums

Rule:  Raimundo appears in every photograph that Yakira does not appear in.


So:  NO Y ------> R
contra:  NO R --------> Y

But, you could have a Y and and R together right or no?  If so, can somebody please explain why and provide an example of whatever to help me make sense of this b.c. when I first saw this, I 'assumed' ( shame on me) that Y and R are NEVER together only later to have discovered in this game through the questions that YES INDEED, they can be together.

Thank you much in advance. 

Vicky :)

Atlas429

Re: 'every'
« Reply #1 on: May 24, 2005, 10:41:41 AM »
Prep 45 Game 3, Albums

Rule:  Raimundo appears in every photograph that Yakira does not appear in.


So:  NO Y ------> R
contra:  NO R --------> Y

But, you could have a Y and and R together right or no?  If so, can somebody please explain why and provide an example of whatever to help me make sense of this b.c. when I first saw this, I 'assumed' ( shame on me) that Y and R are NEVER together only later to have discovered in this game through the questions that YES INDEED, they can be together.

Thank you much in advance. 

Vicky :)

Not sure how to diagram this but if Y isn't in a photo then R MUST be in that photo, according to the rules.

This doesn't mean that if Y is in the photo R can't be in it too. They can both be in the same photo together. If the rule said something like "R and Y cannot appear in the same photo" then (obviously) you couldn't have them together.

Like I said, I have no idea how to diagram this but if you think about it for a second or two it makes sense.

EDIT: So you could have:
IN:R   OUT:Y    (rule 1)
IN:Y   OUT:R
IN YR  OUT:

Notice, as far the rule goes, at least one of these people is in the photo all the time.

V

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Re: 'every'
« Reply #2 on: May 24, 2005, 10:46:13 AM »
Prep 45 Game 3, Albums

Rule:  Raimundo appears in every photograph that Yakira does not appear in.


So:  NO Y ------> R
contra:  NO R --------> Y

But, you could have a Y and and R together right or no?  If so, can somebody please explain why and provide an example of whatever to help me make sense of this b.c. when I first saw this, I 'assumed' ( shame on me) that Y and R are NEVER together only later to have discovered in this game through the questions that YES INDEED, they can be together.

Thank you much in advance. 

Vicky :)

Not sure how to diagram this but if Y isn't in a photo then R MUST be in that photo, according to the rules.

This doesn't mean that if Y is in the photo R can't be in it too. They can both be in the same photo together. If the rule said something like "R and Y cannot appear in the same photo" then (obviously) you couldn't have them together.

Like I said, I have no idea how to diagram this but if you think about it for a second or two it makes sense.


okay that sorta makes some sense.  thank you!

Atlas429

Re: 'every'
« Reply #3 on: May 24, 2005, 10:59:17 AM »
Thanks, hope I didn't confuse you more.

Re: 'every'
« Reply #4 on: May 24, 2005, 11:11:33 AM »
Hi, V.

Look at it this way: 

Assume R is in EVERY photo, period.

If this were true, the stated rule could still be true, because R would be in every photo Y is not in. 

However, R would also be in every photo containing Y, too.  There's no conflict between these two ideas.


I think what you're doing is making an "incorrect negation" of the Rule.  Just because No Y -> R doesn't mean that Y -> No R.

Remember, "incorrect negations" and "incorrect reversals" can never be deduced from an In-Then conditional.  Only the Contrapositive (which is both a negation AND a reversal) can be accurately deduced.   

V

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Re: 'every'
« Reply #5 on: May 24, 2005, 11:46:37 AM »
Hi, V.

Look at it this way: 

Assume R is in EVERY photo, period.

If this were true, the stated rule could still be true, because R would be in every photo Y is not in. 

However, R would also be in every photo containing Y, too.  There's no conflict between these two ideas.


I think what you're doing is making an "incorrect negation" of the Rule.  Just because No Y -> R doesn't mean that Y -> No R.

Remember, "incorrect negations" and "incorrect reversals" can never be deduced from an In-Then conditional.  Only the Contrapositive (which is both a negation AND a reversal) can be accurately deduced.   



Hi Amanda,

Thanks for jumping in and for your perspective.  It's a nice way to view it definately.  My only concern now is this.  There's a list of sufficient terms in PS's Bible that enumerates:

IF
When
Every
Whevever
All
Any
People who
In order to



So when I saw the 'every' I immediately jumped on making it into an if/then statment?  Was this not right of me for this particular game?  In other words, are you implying for me to not have made that statement into an if/then clause?  Is my if/then clause correct and its contra too?
Again:  NO Y -----> R
Contra:  NO R ------> Y

Here are the rules of this game, basically seven friends that can be alone or together in a photograph:

1.  Wendy appears in every photograph that Selma appears in.
2.  Selma appears in every photograph that Umiko appears in.
3.  Raimundo appears in every photograph that Yakiro does not appear in. 
4.  Neither Ty nor Raimundo appears in any photograph that Wendy appears in.



If you don't mind me asking then, how would you approach this game Amanda H.?

Re: 'every'
« Reply #6 on: May 24, 2005, 12:40:40 PM »
So when I saw the 'every' I immediately jumped on making it into an if/then statment?  Was this not right of me for this particular game?  In other words, are you implying for me to not have made that statement into an if/then clause?  Is my if/then clause correct and its contra too?
Again:  NO Y -----> R
Contra:  NO R ------> Y

Here are the rules of this game, basically seven friends that can be alone or together in a photograph:


1.  Wendy appears in every photograph that Selma appears in.
2.  Selma appears in every photograph that Umiko appears in.
3.  Raimundo appears in every photograph that Yakiro does not appear in. 
4.  Neither Ty nor Raimundo appears in any photograph that Wendy appears in.



If you don't mind me asking then, how would you approach this game Amanda H.?

You can properly consider each one of those an "if/then" statement.

1. If Selma is in a photo, Wendy is in it.
2. If Umiko is in a photo, Selma is in it.
3. If Yakiro is NOT in a photo, Raimundo is in it.
4. If Wendy is in a photo, neither Ty nor Raimundo is in it.

1. S -> W           contra: !W -> !S
2. U -> S           contra: !S -> !U
3. !Y ->R           contra: !R -> Y
3. W -> !T & !R     contra  T or R -> !W


There are a lot of deductions that can be made here.  For instance, if !Y, then R, so !W (rule 3).  Or if S, then W, so !T & !R.  If U, then S, then W...and so on.  You can make similar deductions from the contrapositives.  This is probably one of those games (though I haven't seen it) that relies heavily on you making the proper deductions before you get started on the questions.
 

V

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Re: 'every'
« Reply #7 on: May 24, 2005, 04:11:56 PM »
So when I saw the 'every' I immediately jumped on making it into an if/then statment?  Was this not right of me for this particular game?  In other words, are you implying for me to not have made that statement into an if/then clause?  Is my if/then clause correct and its contra too?
Again:  NO Y -----> R
Contra:  NO R ------> Y

Here are the rules of this game, basically seven friends that can be alone or together in a photograph:


1.  Wendy appears in every photograph that Selma appears in.
2.  Selma appears in every photograph that Umiko appears in.
3.  Raimundo appears in every photograph that Yakiro does not appear in. 
4.  Neither Ty nor Raimundo appears in any photograph that Wendy appears in.



If you don't mind me asking then, how would you approach this game Amanda H.?

You can properly consider each one of those an "if/then" statement.

1. If Selma is in a photo, Wendy is in it.
2. If Umiko is in a photo, Selma is in it.
3. If Yakiro is NOT in a photo, Raimundo is in it.
4. If Wendy is in a photo, neither Ty nor Raimundo is in it.

1. S -> W           contra: !W -> !S
2. U -> S           contra: !S -> !U
3. !Y ->R           contra: !R -> Y
3. W -> !T & !R     contra  T or R -> !W


There are a lot of deductions that can be made here.  For instance, if !Y, then R, so !W (rule 3).  Or if S, then W, so !T & !R.  If U, then S, then W...and so on.  You can make similar deductions from the contrapositives.  This is probably one of those games (though I haven't seen it) that relies heavily on you making the proper deductions before you get started on the questions.
 


hey dx5000,

Thanks for setting up those if/then statements.  That's what I did.  And indeed, you're correct it is definately one of those games that you HAVE TO make key deductions before getting started on the questions like combining W, S, and U and then with rule 4 with what can and cannot happen b.c. of the W or NO W.

Anyway, I just want to especially THANK YOU for giving me your input and confirming what I did do right.  I erred with confusing rule 3 but I know why now.  Finally eh.!  Thank you again dx5000!  :)  :)   :)

Re: 'every'
« Reply #8 on: May 24, 2005, 05:29:48 PM »
Hi, V.

Look at it this way: 

Assume R is in EVERY photo, period.

If this were true, the stated rule could still be true, because R would be in every photo Y is not in. 

However, R would also be in every photo containing Y, too.  There's no conflict between these two ideas.


I think what you're doing is making an "incorrect negation" of the Rule.  Just because No Y -> R doesn't mean that Y -> No R.

Remember, "incorrect negations" and "incorrect reversals" can never be deduced from an In-Then conditional.  Only the Contrapositive (which is both a negation AND a reversal) can be accurately deduced.   



Hi Amanda,

Thanks for jumping in and for your perspective.  It's a nice way to view it definately.  My only concern now is this.  There's a list of sufficient terms in PS's Bible that enumerates:

IF
When
Every
Whevever
All
Any
People who
In order to



So when I saw the 'every' I immediately jumped on making it into an if/then statment?  Was this not right of me for this particular game?  In other words, are you implying for me to not have made that statement into an if/then clause?  Is my if/then clause correct and its contra too?
Again:  NO Y -----> R
Contra:  NO R ------> Y

Here are the rules of this game, basically seven friends that can be alone or together in a photograph:

1.  Wendy appears in every photograph that Selma appears in.
2.  Selma appears in every photograph that Umiko appears in.
3.  Raimundo appears in every photograph that Yakiro does not appear in. 
4.  Neither Ty nor Raimundo appears in any photograph that Wendy appears in.



If you don't mind me asking then, how would you approach this game Amanda H.?



Hey, V.

You were NOT wrong in making the "Every" statement into an If-Then Conditional.

You were right about the If-Then Conditional (No Y -> R), and you were also therefore right about the Contrapositive of the If-Then Conditional (No R -> Y).

(And the word "Every" does in fact denote an I.T.C.) 


So yes:  No Y -> R, and No R -> Y. 


You were ONLY wrong in inferring the Incorrect NEGATION of the original ITC (Y -> No R, R -> No Y).  This is apparently why you thought Y and R could never be together.

However, as noted, we cannot assume that the negation or reversal of an ITC is necessarily true.  This is why, for all we know, Y and R can peacefully coexist.  All we know from the ITC (and the contrapositive) is that if one is NOT there, the other one WILL be.  It's also possible that both will appear together.   


Look at it this way.  It's a presidential campaign.  At EVERY campaign, the Vice-President will appear if the President doesn't.  (No P -> VP).  If the VP doesn't appear, the President will.  (No VP -> P).  Obviously, you want at least one of the two to appear at every campaign event.

However, does the fact that at LEAST one will appear at every campaign event mean that they cannot BOTH appear?  Of course not.  They could also both appear together.   

In other words, requiring that at least one appears at every event (or in every picture) does not preclude both from appearing at various events (or in various pictures).

V

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Re: 'every'
« Reply #9 on: May 25, 2005, 08:52:04 AM »
Thank you very much Amanda for your thoughts.  I genuinely appreciate it and esp. the example with the pres.  Further, confirming my if/then and contra set ups.

One last thought if I may.  Is is safe to conclude that if I am given another type of rule set with the following restrictions and / or conditions with word choices of 'every' and / or 'any', to set it up with if/ then and contra?