LSAT logic games approach

kkilambi
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LSAT logic games approach

Postby kkilambi » Wed Sep 11, 2013 9:26 pm

People who are good at logic games, can you provide the step by step procedure of the approach you take to diagram the setup and figure out hidden inferences including what goes on in your mind at each step.

When you are reading the scenario, I guess you would be thinking of a possible way you can set the scenario up. While reading the rules, does everyone fix all the rules in mind and juggle those rules in your mind to analyze the linkage between the rules?

Once you put the pencil on paper, what is the sequence you follow to diagram the entire setup without missing any important information?
do you reread each rule again to jot it down on paper?

I feel I am approaching logic games in an ineffective manner. It would be very helpful to know how you guys crack them.

Thanks.

meegee
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Re: LSAT logic games approach

Postby meegee » Wed Sep 11, 2013 10:57 pm

I'm not an expert, but here's my 0.02

Just keep drilling (aka do a shit ton of logic games).

When you first do them, take as long as you need. Think as long as you need to figure out all the little hidden inferences. If you're honestly stumped, just brute force (plug and chug) your way through, you will discover some inferences that way. Finally, consult books/7sage/videos that explain how that specific game.

After you do a lot of games, you'll notice that they recycle inferences over and over again (they're just dressed up differently).


I just re-read your post. It appears that you should purchase a book on logic games and read through it. Do that first, then do what I said above.

moralsentiments
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Re: LSAT logic games approach

Postby moralsentiments » Wed Sep 11, 2013 11:24 pm

you'll notice that they recycle inferences over and over again


Agreed. It's hard to explain exactly how to approach games because it's something that comes naturally once you have done enough of them.

For me, with the exception of the really weird games that don't show up often, I only utilized two basic set-ups (ordering and grouping) that I was able to do for every game. Sometimes the diagram is a bit different (vertical instead of horizontal, more lines for multiple variable games, etc.), but the basic concept is the same.

The rules will help open inferences. The game itself is what determines the diagram. The key for me was to find which variable the diagram should be built around. An example would be this:
From the powerscore logic games bible pg. 167.
"Doctor Yamata works only on Mondays, Tuesdays, Wednesdays, Fridays, and Saturdays. She performs four different activities--lecturing, operating, treating patients, and conducting research. Each working day she performs exactly one activity in the morning and exactly one activity in the afternoon. During each week her work schedule must satisfy the following restrictions:..."

There are three different variables in this game. 1) Days of the week, 2) activities performed, and 3) time of day (morning or afternoon). What I have in bold is what I would use for the "main variable" with which to work the diagram around. Meaning that I would set up six horizontal lines (or one long line) listing M,T,W,Th,F,and S. Note that I include Thursday even though Dr. Yamata doesn't work on Thursdays. Block out Thursday with "XX" or something so that you aren't thrown off by the number of days in the week not perfectly corresponding.

Above these lines (or line), I would put another line (or lines) to allow for two spaces above each day. One space for the morning, and one for the afternoon.

At this point the rules come into play which may or may not assist in altering the diagram to make the game easier to solve, or merely open up inferences.

Hope this helps a little. I guess it would depend on whether or not you have the logic games bible. If you don't I would buy it now.

Good luck

kkilambi
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Re: LSAT logic games approach

Postby kkilambi » Thu Sep 12, 2013 12:42 am

Thanks guys, your responses were really helpful. I have LG bible but I guess haven't practiced a lot. I'll keep practicing the games a few more times.

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malleus discentium
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Re: LSAT logic games approach

Postby malleus discentium » Thu Sep 12, 2013 4:17 am


bp shinners
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Re: LSAT logic games approach

Postby bp shinners » Thu Sep 12, 2013 12:44 pm

1: Read the introduction and make your setup

2: Read the rules and symbolize them using your preferred method

3: Recheck your symbolization of the rules (seriously, do it)

4: Identify any player that doesn't show up in the rules - this person can go anywhere, and is thus important to keep in your back pocket as a random

5: Make deductions - 'deduction' is a fancy word for 'combination of 2 or more rules'. There's nothing special about it - you're literally looking for the same letter/player/group/slot to show up twice, and that's about it.
a) Check your first rule. See if it interacts with any other rule (either because they share a player, both talk about the same slot/group, both limit distributions)
b) Repeat step 5a for each other rule

6: Make scenarios
a) Check to see if any single player (or group of players) is so constrained that they're only able to fit in 2-3 different places. Make scenarios based on these placements, especially if they interact with any other rules. Bam, you now have 2-3 skeletons that define all the possibilities. This usually comes in the form of blocks for ordering games, an ordering chain with a 'focal point' of one player in ordering games, a Must Be Together rule in grouping games, or a player that shows up in 3 or more rules in any game (count each part of a multi-part rule for this purpose).
b) Check to see if any single slot is so constrained that there are only 1-2 different players that will go there. Make scenarios based on those players in that slot. Bam, you now have 1-2 skeletons that define all the possibilities. This usually comes from an option in an ordering game (if at least one of the option players shows up in other rules), or a group that is almost-but-not-completely filled out in a grouping game.
c) Check if there's anything else that limits the possibilities to 2-3. Make scenarios based on this. This is a catch-all based on those weird rules that sometimes show up (like mauve dinos). It also shows up in grouping games where you’re selecting members from subgroups (3 types of scientists on a panel of 5)/ If you have a rule that you know is weird (because it's not one of the normal rules for that type of game), think about scenarios based around it.

7: Go to the questions
a) Elimination (which of the following could be a complete and accurate) - Don't look at your work. Read a rule, eliminate an answer or two. This is the fastest way, by far, to approach these problems.
b) Conditional ("If _______", or anything that gives you a new piece of information) - Draw a NEW diagram with the piece of information and any deductions you made in your setup. See if the new piece of info interacts with your first rule. Then, your second, and so on until you've gotten through all of the rules. If one of the rules lets you make a deduction, start over again with the first rule (but this time you can skip the rule you already used to make a deduction). If you have scenarios, see if the new piece of info limits you to 1-2 of them, and use them.
c) Absolute ("Which of the following must/could be true/false?") - If you made the deductions, you should be able to answer these without doing any work. Use your setups/scenarios to answer them. If you don't have the answer in your setup, you missed a deduction. If this is a "Which of the following Must Be True?" question, the answer will be the deduction, and you can add it to your setup. THIS IS THE ONLY TIME YOU SHOULD EVER ADD ANYTHING TO YOUR SETUP AFTER YOU FINISH IT AT THE BEGINNING OF THE GAME!

8: Do the Happy Dance.

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francesfarmer
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Re: LSAT logic games approach

Postby francesfarmer » Thu Sep 12, 2013 12:46 pm

bp shinners wrote:1: Read the introduction and make your setup

2: Read the rules and symbolize them using your preferred method

3: Recheck your symbolization of the rules (seriously, do it)

4: Identify any player that doesn't show up in the rules - this person can go anywhere, and is thus important to keep in your back pocket as a random

5: Make deductions - 'deduction' is a fancy word for 'combination of 2 or more rules'. There's nothing special about it - you're literally looking for the same letter/player/group/slot to show up twice, and that's about it.
a) Check your first rule. See if it interacts with any other rule (either because they share a player, both talk about the same slot/group, both limit distributions)
b) Repeat step 5a for each other rule

6: Make scenarios
a) Check to see if any single player (or group of players) is so constrained that they're only able to fit in 2-3 different places. Make scenarios based on these placements, especially if they interact with any other rules. Bam, you now have 2-3 skeletons that define all the possibilities. This usually comes in the form of blocks for ordering games, an ordering chain with a 'focal point' of one player in ordering games, a Must Be Together rule in grouping games, or a player that shows up in 3 or more rules in any game (count each part of a multi-part rule for this purpose).
b) Check to see if any single slot is so constrained that there are only 1-2 different players that will go there. Make scenarios based on those players in that slot. Bam, you now have 1-2 skeletons that define all the possibilities. This usually comes from an option in an ordering game (if at least one of the option players shows up in other rules), or a group that is almost-but-not-completely filled out in a grouping game.
c) Check if there's anything else that limits the possibilities to 2-3. Make scenarios based on this. This is a catch-all based on those weird rules that sometimes show up (like mauve dinos). It also shows up in grouping games where you’re selecting members from subgroups (3 types of scientists on a panel of 5)/ If you have a rule that you know is weird (because it's not one of the normal rules for that type of game), think about scenarios based around it.

7: Go to the questions
a) Elimination (which of the following could be a complete and accurate) - Don't look at your work. Read a rule, eliminate an answer or two. This is the fastest way, by far, to approach these problems.
b) Conditional ("If _______", or anything that gives you a new piece of information) - Draw a NEW diagram with the piece of information and any deductions you made in your setup. See if the new piece of info interacts with your first rule. Then, your second, and so on until you've gotten through all of the rules. If one of the rules lets you make a deduction, start over again with the first rule (but this time you can skip the rule you already used to make a deduction). If you have scenarios, see if the new piece of info limits you to 1-2 of them, and use them.
c) Absolute ("Which of the following must/could be true/false?") - If you made the deductions, you should be able to answer these without doing any work. Use your setups/scenarios to answer them. If you don't have the answer in your setup, you missed a deduction. If this is a "Which of the following Must Be True?" question, the answer will be the deduction, and you can add it to your setup. THIS IS THE ONLY TIME YOU SHOULD EVER ADD ANYTHING TO YOUR SETUP AFTER YOU FINISH IT AT THE BEGINNING OF THE GAME!

8: Do the Happy Dance.

I was reading this thread trying to put into words my approach to logic games, and this is exactly it.

7(c) is a really important and useful point! The questions regularly tell you things about the setup. Make the test work for you!

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wtrc
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Re: LSAT logic games approach

Postby wtrc » Thu Sep 12, 2013 1:15 pm

I want to echo all the advice here. One more thing: if you are done reading the rules and feel like you still don't have much a grasp on the game-- or the questions don't really make sense because it looks like there isn't enough information, or there's a lot there but you don't really see any inferences, especially for a later game, I would go back and take a pause to see if you are missing anything. Those 30 seconds can mean extra points and a huge time saver.

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Jeffort
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Re: LSAT logic games approach

Postby Jeffort » Thu Sep 12, 2013 11:11 pm

wtrcoins3 wrote:I want to echo all the advice here. One more thing: if you are done reading the rules and feel like you still don't have much a grasp on the game-- or the questions don't really make sense because it looks like there isn't enough information, or there's a lot there but you don't really see any inferences, especially for a later game, I would go back and take a pause to see if you are missing anything. Those 30 seconds can mean extra points and a huge time saver.


If/when you feel like you are in that situation at the end of doing the set-up, doing the first "if" question if there is one and putting together a hypo for it and reviewing the rules as you put it together can help you figure out if you are overlooking something.

Making a hypo also gets you more acquainted with how the game works since you have to actively work with all the rules together looking at how they interact in order to build it. If there isn't an "If" question then you can just make a hypo to test an answer choice from the first non-list question in the game. Some of the deductions become much easier to see once you actively try to use the rules to carry out building a valid hypo since you'll run into where the rules interact to restrict certain aspects of the game as you place variables in the step by step chain of reasoning.

It can sometimes be more difficult to see deductions in the abstract since they require seeing the intersection of multiple conditions that happen when the rules are put into action in the context of the base of the set-up with some sort of starting point for application of the rules. Building a hypo makes you apply the rules to something concrete so you can more easily see how placement of one thing has a chain reaction on possibilities for other things in ways that are not as apparent until you start plugging stuff in and looking at how other rules then get triggered each step of the way in the deduction chain.

When you are not yet clear on which aspects of the game have the most 'action' in terms of interactions of the rules that most influence/constrain things, simply just picking one rule and variable to start with to build a hypo and then applying the other rules step by step to play with it and flush out how other rules and variables are effected can be enough to get a good grasp on the game and see the main deductions/points of restriction everything revolves around.

Of course re-read the entire text of the game before doing this if you think you might be overlooking something and forgot to include it in your set-up/list of rules. It's generally a good idea to always re-read the stimulus after building the set-up anyway to catch mistakes, so if you make sure to always do that you will be more likely to find the key deductions in the first place.




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