Setup and Rule Diagrams

[KelseyWoods]

Hi Jay!

For the S W rule, we have to use a conditional diagram because a Block rule would not mean the same thing. A Block rule in a Grouping game would indicate that those variables must always be together. But this rule states that when S is there, W has to be there. That's not the same as saying that S and W must always be together because you could still have W in a photograph without S. So it's very important that you use the conditional diagram with the arrow from S to W and NOT a Block.

The Blocks are only interchangeable with Double Arrows. So an [AB] Block would be equivalent to A B and you could use either rule representation. An [AB] Not Block would be equivalent to A B, and again, you could use either representation. It's most helpful to use the Double Not Arrow representation when you might be linking rules together based on variables they have in common. For example, let's say I have the following rules:

A and B must be together. ( [AB] or A B)
B and C cannot be together. ( [BC] or B C)
C and D must be together. ([CD] or C D)

I could combine all of those rules into one diagram like this:

[AB] [CD]

So as long as you have Double Arrow rules, you can use them interchangeably with Block rules and it's up to you to determine which representation is going to be the most useful for making inferences. But never try to substitute a Block rule for a conditional diagram where that arrow only goes in one direction (e.g., S W) because you don't want to fall into a Mistaken Reversal trap!

Hope this helps!

Best,
Kelsey

[angelsfan0055]

I was doing this as a timed section, and this game for lack of a better phrasing, completely wrecked me.
The game wasn't necessarily hard, but the rules, as discussed in the explanation made it particularly challenging and I diagrammed the first two incorrectly.

If I encounter something like this again, where I'm not sure about 1 or 2 of the rules, what's the best way to proceed? Timing (on this particular PT) was not an issue for me and I even finished 1-2 minutes early. I guess the question is, what should I do if I'm not 100% sure about the rules and what can I do to ensure I at least get a few of the questions correct.

In this game I only got the last one correct.

[Adam Tyson]

A few strategies to consider when the rules have you confused, angelsfan0055:

1) skip the game and go on to the next one immediately. Don't hesitate, time is precious. Just keep moving forward and come back later to see if looking at it anew gives you some greater clarity.

2) Take a look at the first question or two to see if they give you any insight. The first question, if it is a list question, can be a big help in clarifying the rules.

3) if the rules are conditional, as here, get mechanical about them. Don't try to interpret of understand the rules, but just diagram them using the conditional indicators you have, like "every" and "any," and remember that a conditional rule that has a negative sufficient condition and a positive necessary condition means that at least one of those two conditions must occur in any solution to the game. For more on that, see this blog post: https://blog.powerscore.com/lsat/the-mo ... rule-lsat/ . Once you have the diagrams of the rules done, connect them like snapping together pieces of a jigsaw puzzle until you get a more complete picture.

There are more games like this in our Lesson 6, if you are in one of our courses, or in the chapter in the LG Bible on Undefined and Partially Defined games. Check them out, practice your conditional reasoning, and you'll find this game to be much easier the next time you see it or one like it!

[Stephanie Oswalt]

Hello,

We received the below question from a student. An instructor will respond below.

"Rule #3 states Raimudo appears in every photograph that Yakira does not appear in. pg. 237 says "consider the exact relationship between Y and R; when hy is not in the phot then R must be in the photo; and via the contrapositive when R is not in the photo, then Y must in the photo. Thus, when one of the two is not in the photograph, the other must be in the photo. Okay I understand that, however, then the explanation goes on to say " THe operating result of this rule is that either Y or R or both must appear in each photo (note that R and Y can appear in a photograph together; the rule does not prohibit this occurrence)???? This statement seems to contradict rule #3. I don't see how that is possible for both to appear in the same photo -- please explain."

Thanks!

[Luke Haqq]

Happy to address the third rule in this game.

That rule states: "Raimundo appears in every photograph that Yakira does not appear in." We can diagram this as follows:

Y R

In other words, if Y is not in a photograph, then we know that R is. We also have the contrapositive:

R Y

In other words, if R is not in the photograph, then we know that Y is.

These above diagrams tell us some things about the relationship between R and Y. Namely, if one of them isn't in the photograph, then we know that the other one is in the photograph. However, nothing about this relationship precludes them both from being in the photograph. That is what the above explanation is getting at in stating "note that R and Y can appear in a photograph together; the rule does not prohibit this occurrence."

If we instead had something in following generic form,

A B

this would allow us to make an inference that the above two variable can never be together. We could rewrite that as:

A B

That's the type of conditional statement that tells us that two variables can never be together. Here, however, instead of

A B

we instead have

A B (Y R, or R Y, depending how you write it)

So that looks close, but it's actually flip-flopped from the type of conditional statement that would tell us that two variables can never be together. R and Y can be together. We only know that if one is absent, we can be certain that the other one is present.