Setup and Rule Diagrams

[Dave Killoran]

Setup and Rule Diagram Explanation

This is an Advanced Linear: Unbalanced: Underfunded game.

F92_Game_#3_setup_diagram 1.png

The days are chosen as the base because they have an inherent order. The streets, although numbered from 1 to 8, can be cleaned in any order and thus make an inferior choice for the base. The morning and afternoon variable sets are then stacked above the days (either can be on top), and the street numbers fill in the spaces.

The five days with two time slots create 10 available spaces. Because there are only 8 streets, two “empty” variables are created, in this case represented by “X” (however, any variable would suffice, such as “E”). The addition of these two empty slot variables negates the Underfunded aspect of this game (the game becomes ten variables into ten spaces). Also, the assignment of the two empty slots to Friday morning and Wednesday afternoon makes handling the two X variables a non-issue. The further assignment of streets 4 and 7 reduces this game to six variables being placed in six spaces, a very manageable situation.

The combination of the last two rules forces 8th street to be cleaned on Monday afternoon. 8th street must be cleaned before 4th street, so it must be cleaned on Monday, but the last rule indicates that 8th street cannot be cleaned in the morning, so 8th street must be cleaned on Monday afternoon. Note also that street cannot be cleaned on Monday, but that it could be cleaned Tuesday afternoon since that is after street 4 is cleaned.

Finally, the combination of the Not Laws in the last rule, the previously placed streets, and the sequence leaves only a limited number of streets available for cleaning on Monday morning. The key inference in this game is that only streets 1 and 3 are available for cleaning on Monday morning. Question #15 is a great example of how the LSAT makers test your ability to see inferences.

[kpayne]

Game #3 from February 1992

In the set up, we are supposed to infer that Streets 1 and 3 can only be cleaned on Monday morning. I am not seeing why they could not be cleaned on Wednesday morning as well.

Please advise.

[Dave Killoran]

Hi Kpayne,

Thanks for the question!

That setup indicates that the only two streets that can be cleaned on Monday morning are 1 and 3. That's because 4 and 7 are assigned elsewhere, 2, 5, and 8 can't be cleaned in the morning, and 6 can't be cleaned on Monday due to the sequence in the fifth rule. So, only 1 or 3 is left for Monday AM. However, that doesn't mean that 1 and 3 themselves can ONLY be cleaned on Monday morning. While one of the two will always be cleaned there, the other has to be cleaned on a different day.

Ultimately, the 1/3 notation there means those are the only two options for that slot.

Please let me know if that helps. Thanks!

[David Boyle]

From page 4-32 of the lesson books. Game #1 from February 1992

In the set up, we are supposed to infer that Streets 1 and 3 can only be cleaned on Monday morning. I am not seeing why they could not be cleaned on Wednesday morning as well.

Please advise.

Hello kpayne,

The setup on page 4-108 says that Monday morning must be either street 1 or 3; it does not say or imply that that is the ONLY day and time that 1 and 3 could be cleaned. If it did, then one of them would have to be not cleaned! since there are two streets, but only one Monday morning...

(Wednesday morning might work, e.g.,

8 2 X 6 5
1 4 3 7 X

as the order, showing 3 could be on Wed. morning.)

Hope this helps,
David

[kpayne]

Thank you both!

[jcough346]

Is it preferable to stack both rows for morning and afternoon or to use one line of sequencing?

[David Boyle]

Is it preferable to stack both rows for morning and afternoon or to use one line of sequencing?

Hello jcough346,

This is an advanced linear game, so it is probably most helpful to have a morning stack and an afternoon one, rather than putting it all in one line.

Hope this helps,
David

[HBaxter]

What is the best strategy for moving from question to question when your diagram and inferences become very detailed and complicated? I know that we should create a new diagram for each question. How much detail should we copy over to the new diagram?

For example, the homework for lesson 4 Game #3: June 1992 Questions 18-24.

The complete diagram is very detailed and it would be easy to miss something if I'm copying all that detail over and over, it seems like that is increasing my margin for error. If I use a blank diagram and rely on looking back at the detailed one for the rules and inferences, it also seems like I have a high chance of missing something. Should I draw a new diagram of only the open spots? That seems like a lot to think through. If I draw a detailed diagram in pen and answer the questions in pencil, I lose all my data from question to question.

What is the best option for using the least amount of time while reducing my margin for error from question to question when the initial diagram has so much information? My preference would be to use a transparent sticky note over the initial diagram for each new question, but I doubt the test proctors would approve that method for the actual test!

[Adam Tyson]

Local diagrams in this game should start with what you know is always true based on the original rules and inferences, HBaxter. 8 is Monday afternoon, 4 is Tuesday morning, 7 is Friday morning, and both Wednesday afternoon and Friday morning are crossed out. Always begin there. Don't bother copying over the not-laws or the AM and PM labels, because you can always look at the main diagram to get those.

Then, add in the local restriction. For example, in question 13, 6 has to be in the morning. There is only one morning where it could go, Wednesday, so put it there. 2 is supposed to go before 7 and that can only happen on Tuesday afternoon, so put it there. Finally, ask yourself if you can make any additional inferences. What's missing, and where could they be? Can you place anything else with any certainty?

The same could be said of any game, whether there is a lot of info in the main diagram or very little. Local diagrams start with what you know, then what you are told, and then what you can infer. Don't over-diagram it by filling in a bunch of stuff that merely could occur - leave those things out until and unless you have to test an answer choice, and then only if you have finished sorting out the losers from the contenders.