Diagram

[sgorginian]

Here's how I put the chain per the constraints, please let me know if its right. If so, then I'll do the logic chain and reply here on how that goes. thank you!

1. If G services on finance, then H serves on incentive.

Gf --> Hi

2. If L serves on finance, then M and U both service on incentive.

Lf --> Mi
Lf --> Ui

3. W services on a different committee than from the one which Z serves

Wi --> Zf , Zi --> Wf
Wf --> Zi , Zf --> Wi

4. U serves on a different committee from the one which G serves.

Ui --> Gf , Gi --> Uf
Gf --> Ui , Uf --> Gi

5. If Z serves on the finance committee, so does H.

If Zf --> Hf
If -Hf --> -Zf [if there are only two committees to be on, why can't you say for this Hi --> Zi. I see how its not what the constraint says, but it truly is the contra+ of this statement.]

[noah]

These all look correct, though for the first two you did not write out the contrapositive. Also, if there are only two committees, and if everyone must serve on one, then there's no difference between saying someone is not on finance and saying that the person IS on incentive.

Good luck with the game and tell me how it goes.

[jrdn_pearl]

fyi...if anyone has trouble with this game it is in the LG strategy guide. the double arrow makes or breaks this game!! wow, i set up the sketch fine except for the double arrow and i had alot of trouble.

[noah]

Good point. I personally dislike double arrows, as I find it hard to remember to read them in both directions, so I put an "X" at each end, or a small circle. That way when I see it, I know to pay attention. If I see an arrow, I may think that I should not read up that arrow, as usually you don't.

[Rachel.Jay.Shapiro]

I'm having a hard time understanding why the following conditions

"Wharton serves on a different committee from the one on which Zhu serves"
and
"Upchurch serves on a different from the one on which Guzman serves"

imply biconditionality. If, for example, Wharton's serving on finance necessitates Zhu's serving on incentives, and Zhu's serving on finance necessitates Wharton's serving on incentives (the contrapositive), why is there a need for the two additional conditional statements? What makes these statements different from the following: "Wharton and Zhu cannot serve on the same committee", which I believe would not result in biconditionality. Are there typical biconditional statements that can be expected in binary grouping games?

Please explain! Thank you!!

[noah]

Hi Rachel!

Let me see if I can clear it up:

"Wharton serves on a different committee from the one on which Zhu serves"
and
"Upchurch serves on a different from the one on which Guzman serves"

imply biconditionality. If, for example, Wharton's serving on finance necessitates Zhu's serving on incentives, and Zhu's serving on finance necessitates Wharton's serving on incentives (the contrapositive), why is there a need for the two additional conditional statements?

The issue is that you also have to be ready to know the consequences of Wharton serving on finance and Zhu serving on incentives. I might be wrong, but it seems like you're saying: If I know that Wf --> Zi, then I already know that Zi --> Wf, and while that's true in this case (because the rules tells us they can't serve on the same committee), in other situations, that would not be true. For example, what if the rule were simply "If W serves on finance, Z must serve on incentives"? Would you know that Z on incentives requires W on finance? No -- they could both be on incentives.

To give you another example, if I say "If H is on the team, then Q is not" can I infer "If Q is not, H is on the team"? No, I can't -- it's possible they're both off the team. If I were to try to make the H and Q example similar to the Zhu and Wharton one, I'd have to change it to "H and Q must do different things after school, and the only choices in our poor town are to be on the team or off it." Does that makes sense?

What makes these statements different from the following: "Wharton and Zhu cannot serve on the same committee", which I believe would not result in biconditionality.

Those are the same thing, and the one you've written also ends up requiring a double arrow. If this game were about whether you're on the committee or not, then the interpretation would be different. Note, I don't like double arrows, as I've trained myself not to read "against" the arrow, so I put circles or Xs at each end of the line.

Are there typical biconditional statements that can be expected in binary grouping games?

This is a typical one -- it's more common in situations in which the game is not about in or out, but whether the elements are sent to this or that option (i.e. varsity or junior varsity, instead of on the team or off).

Does that clear it up?

[laura.mirlyn]

I have trouble understanding why on rule 1 "if Guzman serves on the finance committee, then Hawking serves on the incentives" Guzman and Hawking could be together in the incentives committee?

I know that:
Gf -->Hi contrapositive - Hf-->Gi

Isn't the contrapositive that if H is in finance then G will be in incentives, so how they both could be in the incentives at the same time??

can somebody help me please!

[stacksdoe]

I have trouble understanding why on rule 1 "if Guzman serves on the finance committee, then Hawking serves on the incentives" Guzman and Hawking could be together in the incentives committee?

I know that:
Gf -->Hi contrapositive - Hf-->Gi

Isn't the contrapositive that if H is in finance then G will be in incentives, so how they both could be in the incentives at the same time??

can somebody help me please!

Hi Laura,

I'm not sure what your asking, but ill try and make an attempt: So your absolutely correct in your interpretation of the first rule.
If Gf then Hi and with the contrapositive: if Hf then Gi. This is why in question number 1, answer choice A is incorrect. However, if your asking how can they both be in the incentives group? I can certainly answer that. They both can be in the incentive group because the rule never tells us what happens when H is incentive, thus, Hi doesn't not prevent Gi. We only know two things what happens when Gf and what happens Hf (via the contrapositive as you and I both have pointed out. To assume that Hi prevents Gf is to make a reasoning error, known as denying the antecedent or as kaplan and other lsat material likes to call it Mistaken Negation. Nothing about your original rule and it's contrapositive prevents H and G both being on incentives.
I hope this makes sense.

[dontmesswmeow]

For this type of IN & OUT game,

is it the quickest efficient way to draw the In & out diagram that is taught in Manhattan prep courses?

I was jut wondering if that's the case.

I find it useful and the most accurate way to solve problems in this type of game but at the same time it is daunting to draw it under time constraint.

[ohthatpatrick]

Generally speaking, In/Out games require that we spend a little more time setting up our rules/diagram.

The PAYOFF, though, is that the questions should take LESS time than average. After all, at least of few of them will usually be questions for which the diagram tells us all we need to know, and tells us quickly.

So don't worry that the setup takes longer. It's just a different allocation of time. We spend more on the setup, less on the questions.

Whenever I see I'm doing In/Out, I let out a little "Ugh" because I'm lazy and I know I need to do more than average work with setting up the rules/diagram, (it feels like "Great, I have to do this mindless busy work"). But I'm not worried about getting through the game in time as a result.

There are several different methods to setting up In/Out games, so you might find that a different one from the one we show in our books works better for you.

Generally, the more efficient the method is, the weirder it is to learn and get to a brain-dead level of familiarity.

The less efficient methods are easier to get into because they basically just have us do what we always do (when you see a conditional statement, write it conditionally on your page and write its contrapositive .... when you have multiple conditionals, see if they chain together)

Try to get enough reps at one given method that you feel at ease with the logic of how to set up the diagram. And remind yourself "it's worth it", because you'll be able to dominate at least a few of the questions, if you have a good diagram.

[AnthonyR976]

Can somebody at Manhattan Prep post the diagram for this? I'm having trouble on a few questions and want to first ensure my diagram is correct. Thanks!