"Reusing Work" Eliminating MCs

[LawCraft]

Disclaimer: I have just started my preperation for the LSAT; I am very new to this and I want to make sure I am learning the correct strategies from the onset. I would really appreciate your insight.

I am trying to make sure I understand the concept behind "Reusing Work." This section talks about the importance of leveraging information presented in one question to help eliminate answer choices in a following question.

Suppose the first question in a game produces a scenario where A is in the first position. Then, the second question asks for a complete and accurate listin gof the positions A can occupy. Based on the first question, A can clearly be in the first position, and therefore you can eliminate any answer in the second question which does not contain the first position as a possibility.
-PowerScore LSAT Logic Game Bible, (c) 2014

This makes sense.

...suppose the third question in the same game states, "If A is in the third position... You cannot use the information from the first question to help answer the third question because A was in the first position in the first question, and thus does not fit the condition imposted in the third question.
-PowerScore LSAT Logic Game Bible, (c) 2014

But, does the third question also help us answer the second question -- just as the first question did?

The book does not address this possibility and I would like to understand how it all ties together. I think this might relate to Global Questions vs Local Questions.

Do we assume that Question 1 & 2 are global and Question 3 is local? Therefore, Question 3 must be answered independently? Or since A is placed in the third position by question prompt, we can assume that this is a legal position; therefore, we can conclude that the third position is also a possible for A to occupy?

I am unsure of when the question alters the rule of the game. Thus, I do not want to prematurely eliminate an answer choice.

[Dave Killoran]

Hi LawCraft,

You ask a good question. First, the information in question #3—namely that A can be third—would definitely apply to question #2. The Global aspect of question #2 allows for Local scenario information, and since #3 specifies that A can in fact be third, that info could be used in #2. I don't address this point right there in the book in order to avoid information overload. However, later in the books when doing actual games, this type of idea comes up again, and the idea of skipping global questions like #2 for after you've completed all the remaining questions is referenced.

So, you have the right idea, and you'll see the idea come up again as you get further into the book

Please let me know if that helps. Thanks!

[LawCraft]

Thank you Dave. You helped!

I have a quick follow-up question:

The Reusing Work example on pg. 18 is true only if the first question is Global, right? Is that the implied assumption?

The first question produces a scenario where A is in the first position. Does it matter whether this question is Local or Global with respect to the Reusing Work strategy?

[Dave Killoran]

Hi LawCraft,

Glad this is helping so far!

Actually, it isn't assumed that question #1 is Global, and it doesn't need to be the case that #1 is Global in order for it to apply to question #2. That could be confusing, so let's look at it more closely.

As the book states, "the second question asks for a complete and accurate listing of the positions A can occupy." In other words, if A can—in some solution to the game—be in a certain position, that position needs to be in the correct answer to question #2.

So, let's say question #1 is Global, for example it is a Global, List question. The correct answer to that question will be a workable solution, and wherever A appears will be a valid answer to question #2 (meaning that if A is second in the correct answer to #1, then "second" must appear in the correct answer to question #2). So a Global question for #1 works to help us in answering #2.

Now, let's say that instead of being Global, that Question #1 is a Local question. Maybe the question reads "if C is fourth, which of the following must be true?" And in the process of answering this question, you determine that when C is fourth, A will be first. If you think about the relationship of that information to question #2, because #2 is asking for any place that A could appear, you would then know that since A can be first in question #1, that "first" must appear in the correct answer to #2. So a Local question for #1 also works to help us in answering #2.

The bottom line is that, under the specific situation we are discussing, it doesn't matter if the first question is Global or Local—it still helps us answer Question #2. Why is that? Because of the nature of the question in #2. It just wants a list of all the places A could appear, under any type of scenario or restrictions. So, if A can appear in that place in some solution to the game, it will apply to Question #2. It also means that if the nature of Question #2 was different, that might change everything, and perhaps then the solution to #1 wouldn't apply. It's sensitive to the specifics of the questions involved.

Here's an alternative scenario that might shed some light on the last sentence of the prior paragraph. Let's say that the question stem to Question #2 reads, "If C is fourth, which of the following is a complete and accurate listing of the positions A can occupy?" Now, only solutions where C is fourth apply to this question, which totally changes what information we use. For example, if Question #1 is a Global List question with a correct answer where C is third (as opposed to fourth, which is what we need for #2), then we can't use that info to answer Question #2. Or, alternatively, if Question #1 is a Local question where again C isn't fourth, then the solution wouldn't apply again. Only situations where C is fourth would work, regardless of whether the question is Global or Local.

So, ultimately, you have to read the context and determine whether the solution under examination conforms to the needs of the question you are trying to answer. If it does, move ahead. If not, you can't go any further and you have to seek info elsewhere in the game. Side note: as complex as this all sounds, once you've done a bunch of games and looked at these situations, it gets a LOT easier. I'd bet you'll master this skill pretty easily once you've done it a few times

Please let me know if that helps. Thanks!