Setup and Rule Diagrams

[Robert Carroll]

Aaron,

The rule as stated does indeed say the following:

N R + S

Remember that "not reduced" isn't a group. The only group is the group of areas that are reduced. So when (part of) the rule says the following:

N R

This means that N and R can't both be reduced. If neither one were reduced, then they wouldn't be "together" in a group. This is what a Double-Not Arrow says - it does not forbid two variables from being together, but from being together in a group.

Compare these two:

A B

C D

The first say that each variable excludes the other. The latter is not the same! It says that the lack of one variable requires the other. The latter, not the former, is a rule that would forbid the two variables from both being out.

You don't have such a situation here. The correct contrapositive is two Double-Not Arrows:

N R

N S

That's different from this:

N R + S

because the last thing I just listed is not what the rule or its contrapositive says, and is thus not a valid inference in this game.

I think all the confusion can be traced to a misinterpretation of what a Double-Not Arrow means. It means "those two can't both be in a group together." If you remember that "Not Reduced" is not a group at all, then the misinterpretation should disappear. If N and R are both "Not Reduced," the Double-Not Arrow is perfectly satisfied, as all it cares about is that they are not in a group together.

Robert Carroll

[Dave Killoran]

Hi,

Thanks for the question! To start, this rule follows the parameters of the conditional relationship I discuss this post: http://blog.powerscore.com/lsat/bid/263 ... -Condition. Understanding this rule type is extremely important, so please read through that when you get a chance. Basically, the gist of the article is that this rule is two separate statements in one, and thus can be treated as one statement, or two.

When treated as one statement, you have "and" in the necessary condition. When taking the CP of that, it becomes "or," and the terms are negated. So, this original statement:

• R
  N +
  S

Which becomes the following when the contrapositive is taken:

• R
  or N
  S

That reverses and negates both terms (and "and" becomes "or" when that occurs).

That's a start, so please let me know if that helps. Thanks!

[LSAT2018]

For the Rule, if N is reduced, neither R nor S is reduced: N → Not R and Not S).
The contrapositive would be R or S → Not N.

Would it still apply if R and S were reduced? So R and S → Not N.

[Smithm2710]

Hi! I diagrammed/solved this game by listing out possible solutions based on the L, M, and R rule. I produced five solutions, but I’m not sure if one of them is correct based on the N/S rule. (The N/S rule being N S.)

Here are the five solutions I came up with - solution 5 is the one I was unsure of.

1. Reduced: G, L, M, N, W (Not: P, R, S)
2. Reduced: G, L, M, S, W (Not: N, P, R)
3. Reduced: G, L, R, S, W (Not: M, N, P)
4. Reduced: M, P, R, S, W (Not: L, N, G)
5. (?) Reduced: G, M, P, R, W (Not: L, N, S)

Does solution 5 above violate the N/S rule, or is it a viable solution?

Thanks!

[Jonathan Evans]

SmithM,

Good question!

Yes, your solution 5 does not violate any rules and is a possibility.

• You have exactly 2 of L, M, and R, in this case M & R,
• G by itself implies nothing, so no problem there.
• P implies no L. You haven't violated this rule.
• W implies nothing.

In other words, your solution works.

However, I would be cautious not to invest too much work in trying out possibilities at the outset. While you will often come up with several valid solutions, these solutions might not be of great value if you have to do the work again anyways during local/global questions. In addition, you might spend considerable time working through possibilities at the outset only to determine that there are substantially more that you have not considered.

In this case, there are not too many possibilities. If we only had the LMR restriction, we would have 30 total possible combinations; therefore we would expect to have significantly fewer possibilities given the other rules. I haven't figured out exactly how many there are, but this gives you an idea that this is probably a more restricted game.

In this case, you might draft up a template or two depending on which of L, M, and R you choose, since there are only three possible groups here. For instance, in both groups with R selected, you can exclude N. In both groups with L selected, you can exclude P.

Thus, you'd get:

• Template 1: L R G S W selected, M P N not selected
  
  Template 2: M R (3 of G P S W) selected, L N (1 of G P S W) not selected
  
  Template 3: M L (3 of G N S W) selected, R P (1 of G N S W) not selected

This would likely be as far as I'd go with any templates on this game. Notice that in template 3 you'd have to make sure you don't pick N and S together; in template 2, you'd have to be careful to remember that G and S together imply W.

I hope this helps!

[thecmancan]

Hi all.

On the explanations, there are a LOT of inferences playing different scenarios like if L is selected what happens, or when R is selected what happens.

Given that a lot of the questions can be solved quite easily with just the correct application of the rules, do you think that we should be trying to draw all these inferences under timed conditions?

The first try I did this 6 right out of 7 in 11 minutes. I, in no way, contemplated any of those sets of inferences before heading into the questions.

Were those included as just a very thorough and clear list of the various inferences that COULD be drawn but need not be under time pressure?

Thank you, I'm a big fan of the Bibles, podcast and Dave / Jon's reddit presence.

[Dave Killoran]

Hi all.

On the explanations, there are a LOT of inferences playing different scenarios like if L is selected what happens, or when R is selected what happens.

Given that a lot of the questions can be solved quite easily with just the correct application of the rules, do you think that we should be trying to draw all these inferences under timed conditions?

The first try I did this 6 right out of 7 in 11 minutes. I, in no way, contemplated any of those sets of inferences before heading into the questions.

Were those included as just a very thorough and clear list of the various inferences that COULD be drawn but need not be under time pressure?

Thank you, I'm a big fan of the Bibles, podcast and Dave / Jon's reddit presence.

Hi Cman,

Thanks for the question, and the kind words! The list of inferences discussed in the book and in the first post in this thread is intended to show the scope of what you can know about this game. Most students wouldn't see it all, but that doesn't mean there isn't value in showing what they could have known. I often say this about inferences: it's great to have them all, but rare, and you can survive in most cases without every little insight.

With that thought in mind, some inferences are more important (or more difficult) than others. For example, the following to me isn't an inference, just the natural workings of a "2 out of 3" group:

• 1. Because two of the group of L, M, and R must be reduced:
  
  When L is not reduced, M and R must be reduced.
  When M is not reduced, L and R must be reduced.
  When R is not reduced, L and M must be reduced.

So, while we wrote that all out in explanatory text, I certainly wouldn't on the test! I'd just know how it works (from prior studying) and move on from there.

The same principle applies to several other of those items, such as #2 and #3. Once I knew about the LMR group, I naturally looked at the remainder, and quickly drew that inference. All I did was write out "G, P, W, N/S" above the last three spaces, though, which meant I knew the other implications but didn't have to worry about writing them down. We do so in the books/courses/forum as a matter of clarity though! With the other inferences, they are also written out for clarity, but I simply knew they existed and then used them when appropriate in the game. This game is a bit unusual though in that the rules really connect extremely well, and any good test taker would have to see that there were going to be a lot of inferences. Contemplating those first is often what allows you to go faster later in the game

This is of course the primary dilemma in explaining anything: how far do you go in the setup to show what could have been known vs what to do with it? I typically err on the side of showing a lot upfront because it makes explaining the entire thing easier and because it shows how much info exists in these games (which many people don't realize at first). However, my operational approach is one I've discussed elsewhere—I typically jot down a few inference representations as needed, which doesn't take long at all. I do not write out lengthy or detailed breakdown like the one seen here. My diagram, then, looks much like the diagram at the top of the prior page (with the exception of the last rule "Exactly 2 of..." I use my block on the two spaces for that).

Hopefully that makes sense, but if not just let me know. Thanks!

[DW007]

Hello!

I recently purchased the Powerscore books and have been working through the questions. I understand that this thread was last active three years ago, but I have the same question as copied below. Stephanie indicated that an instructor would respond to the question. Any chance an instructor could help me out?

Thanks in advance for your help!

We recently received the following question:

I'm having issues understanding the N-R-S connection from the scenario on page 324. Game 1 Oct 1996 Q 6-12. As well as the Diagram and explanation from pg. 326 [PowerScore Logic Games Bible 2017 edition].

The part about when N is reduced neither R nor S is reduced I think I understand. I believe if I were to say "when N IS reduced S&R are not reduced" ?

My confusion is to the counter positive and conditions it creates. From the written scenario I understand the counter positive should be "when R or S is reduced N is not reduced" The way I'm reading the Diagram it appears N-R and N-S are listed as two separate double not arrow rules. From the way it appears in the diagram if N is in the (Not Reduced) group, both R and S have to be reduced. But this would create issues with question 9's correct answer. How can R and N both be in the same group? Sincerely, Aaron

An instructor will respond to this question below. Thanks!

[Stephanie Oswalt]

Hi DW,

Thanks for the question! Please refer to the posts from Robert Carroll and Dave Killoran on this thread--they are in direct response to the question I had posted on behalf of a student. I quoted those responses below as well.

If you have further questions after reviewing those responses, please let us know!

Thank you!

Aaron,

The rule as stated does indeed say the following:

N R + S

Remember that "not reduced" isn't a group. The only group is the group of areas that are reduced. So when (part of) the rule says the following:

N R

This means that N and R can't both be reduced. If neither one were reduced, then they wouldn't be "together" in a group. This is what a Double-Not Arrow says - it does not forbid two variables from being together, but from being together in a group.

Compare these two:

A B

C D

The first say that each variable excludes the other. The latter is not the same! It says that the lack of one variable requires the other. The latter, not the former, is a rule that would forbid the two variables from both being out.

You don't have such a situation here. The correct contrapositive is two Double-Not Arrows:

N R

N S

That's different from this:

N R + S

because the last thing I just listed is not what the rule or its contrapositive says, and is thus not a valid inference in this game.

I think all the confusion can be traced to a misinterpretation of what a Double-Not Arrow means. It means "those two can't both be in a group together." If you remember that "Not Reduced" is not a group at all, then the misinterpretation should disappear. If N and R are both "Not Reduced," the Double-Not Arrow is perfectly satisfied, as all it cares about is that they are not in a group together.

Robert Carroll

Hi,

Thanks for the question! To start, this rule follows the parameters of the conditional relationship I discuss this post: http://blog.powerscore.com/lsat/bid/263 ... -Condition. Understanding this rule type is extremely important, so please read through that when you get a chance. Basically, the gist of the article is that this rule is two separate statements in one, and thus can be treated as one statement, or two.

When treated as one statement, you have "and" in the necessary condition. When taking the CP of that, it becomes "or," and the terms are negated. So, this original statement:


R
N +
S

Which becomes the following when the contrapositive is taken:


R
or N
S

That reverses and negates both terms (and "and" becomes "or" when that occurs).

That's a start, so please let me know if that helps. Thanks!
Dave Killoran

[menkenj]

Hi there,

I diagrammed this question as an In/Out diagram with three worlds. Not sure how to format below as in/out charts but here it is as a list:

1. L, M/R, G, S, W (IN) ; P, R/M, N (OUT)
2. P, M, R, G/S, W (IN); L,N, S/G (OUT)
3. L, M, G, N, W (IN); P,R, S (OUT)

I see the suggested diagram in the thread looks a bit cleaner. Does diagramming this question as 3 in/out worlds make for less efficient work? The diagram took a long time but then the questions went super quick. I know this is how worlds typically works, however my question is, would it have been more efficient for this game to use the suggested diagram instead? Does it matter?

Thanks!