Q12

[dlclay7]

Rule change for question 12

When a new rule is presented or a change is made in an if situation what is the best strategy for approaching this type of question

Shpuld I go back to orginal constraints and start over

Please advise me best approach and complete this diagram and apply to the question

Thanks

[aileenann]

Thanks for your question!

A couple of thoughts. The best thing to do when you run into a question that asks you to change one of the constraints is to save it for last. This is usually one of the very last questions anyway, but you want to make sure it is absolutely *the* last question you do. That way you can modify your diagram without having to worry about changing it back afterwards.

The other thing you'll want to do is go back to the original phrasing of the constraints. You can't just change the one thing on your diagram that the rule directly refers to, because there can be all sorts of consequences for your inferences too. Unfortunately this is the one area where the more inferences you make, the more work you're going to have to do. I'd say this is especially difficult to keep track of in open assignment games, where very often lots of inferences are all working together.

Most of the time I don't think it's necessary to start completely from scratch, but you do have to keep an eye out for any inferences that would involve the constraint that's been eliminated. If it's a particularly interwoven game - with lots of inferences - it might just be better to start over.

I'm going to defer for a little bit as part of posting a diagram. Let me know when you've taken a stab at it, and then we'll take it from there

[Lattia.Baker]

I am having difficulty merging (diagramming) new rule(s) with the orginal constraints... can you share a diagram that depicts merging the new rule(s) with the existing constraints or point to another PT LG within the Forum that illustrates a change in constraint for relative ordering? Thanks...

[giladedelman]

Great question!

I've uploaded an image depicting both the initial setup and the setup with the new constraint swapped in.

Notice that it's not really a question of "merging" the new constraint; rather, you're substituting it in for one of the original ones. Personally, I find it much easier to start my diagram from scratch, which on a Relative Ordering game shouldn't take very long. (And I completely agree with Aileen that it's best to save these questions for last.)

Does that clear things up for you? Now that you see what the reworked diagram should look like, why don't you take another stab at question 12? And let us know if you have any more questions about "constraint switch" questions.

[monicaiannacone]

For this question, I'm able to figure out the answer but only after about 4 minutes of drawing my new diagram, then trying all of the answer choices until I get to the answer that must be false. However, my method was extremely time consuming!

Is there a better way to make inferences without writing out all of the possiblities? Or a way to answer this question quickly?

Otherwise, it seems worth skipping (for me at least, since it took several minutes).

Thanks!

[timmydoeslsat]

For this question, I'm able to figure out the answer but only after about 4 minutes of drawing my new diagram, then trying all of the answer choices until I get to the answer that must be false. However, my method was extremely time consuming!

Is there a better way to make inferences without writing out all of the possiblities? Or a way to answer this question quickly?

Otherwise, it seems worth skipping (for me at least, since it took several minutes).

Thanks!

With this being a must be false question, I normally would look at all of the answer choices before trying one of them to test. This is because I would really dislike seeing that choice E, for example, was obvious, yet I wasted my time trying out A and B, while simply looking at E would have saved time.

However, in this case of a partial lineup for the answer choices, I would approach it differently.

We have new information given to us that requires us to dismiss our global diagram and create a new one.



My new diagram is the bottom one. I decide to check the most obvious indicators: the first and sixth slots if they are given in answer choice. Perhaps this would quickly give me answer. For example, I know that either S or Z must first. I would also check to see if some variable was last that cannot go last.

I see nothing but its ok, I dedicated maybe 15 seconds to that.

I will now go in order A-E.

A) S1 Z2 M6 - No reason to check this one. I know that this can work. So we have S and Z at the beginning and M last. We know we can manage a valid hypothetical out of this. Nothing stands out as must be false.

B) S1 V3 O5

S _ V_ O _

S being first makes this one easy to not check it! All I would have to do is make Z wither 2 or 4 and put either L/M last. No need to do work here.

C) S3 L4 V5

_ _ S L V _

I have to put O last to accommodate the V-O rule. But then I will not be able to put M after S. This must be false. No need to check the others.

[monicaiannacone]

Thanks for the quick response and diagram! I'll try this question again and look for inferences instead of just trying every answer (and wasting my time!)

Thanks again!

[tbhaga]

Another way to think of this solution is to go through the constraints one by one once you redraw the diagram. As stated before the correct answer is (C) and as it is a "If" question then you are determining which answer must be false. I found the answer quite quickly after mentally redrawing the diagram and moving M to its own line. After that process I saw (C) immediately stated that Singh (S) was in the 3rd seat which is impossible because Z is still the only variable that can Float in front of S. Thus it is instantaneously False.

[sh854]

why doesn't M have to go second?

[christine.defenbaugh]

why doesn't M have to go second?

Thanks for posting, sh854!

Why would M have to go second? We know that M comes after S now, but it doesn't have to come immediately after S, nor does S have to go first anyway (Z could always go first). M can actually go anywhere EXCEPT slot #1.

Let me know where you're having trouble with the altered diagram for this question, and we'll sort it out!




This is an older question, but I wanted to answer it for future students:

For this question, I'm able to figure out the answer but only after about 4 minutes of drawing my new diagram, then trying all of the answer choices until I get to the answer that must be false. However, my method was extremely time consuming! Is there a better way to make inferences without writing out all of the possiblities? Or a way to answer this question quickly?

SEXY SHORTCUT TIME!!

Okay, so, timmydoeslsat gave his sexy shortcut above - looking for who can be first/last - and I like it. He's using our most restricted slots to see what's up. But, in this case, it didn't bear fruit.

There's another fun shortcut to use on a problem like this, though: glance at your most restricted players. For that, S and O are going to be the baddies: O has 3 people that must come before him, while S has a whopping 4 people that have to appear after him.

Starting with O - that means that O can only appear in slots 4, 5, or 6. If we saw O in 1, 2, or 3, that would be our must be false. No hits on this one.

Moving to S - with 4 people appearing AFTER S, S can only go in slots 1 or 2. Slots 3-6 wouldn't leave enough room for all four to go after. AND WHAM. Singh in seat 3 is in (C).

Sexy shortcuts don't always work out, but they sure are sweet when they do!