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 Dave Killoran
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#88139
Setup and Rule Diagram Explanation

This is an Advanced Linear: Balanced game.

The game scenario presents a situation that at first appears relatively simple: a shuttle van makes four separate stops, and at each stop one of four passengers exits. This creates an Advanced Linear game that is Balanced:

PT55-Oct2008_LGE-G4_srd1.png

This scenario is easy to understand, but the second and fourth rules contain language that makes this game much more challenging than it might first appear.

Rule #1. The first rule establishes that L must be the first or second stop:

PT55-Oct2008_LGE-G4_srd2.png

Rule #2. Some students initially read this rule to mean that R exits when the shuttle reaches M (thus creating an RM vertical block). However, the language in the rule simply states that R is “still on board” when the van reaches M. This means that R can exit when the van reaches M, or it can exit after the van reaches M (and so no Not Laws can be drawn for this rule). The only possibility ruled out is R exiting the van prior to reaching M. Thus, the best diagram for this rule is:

PT55-Oct2008_LGE-G4_srd3.png

Functionally, this rule is tough to track because once stop M is reached, R is not obligated to exit at that point, and can still exit at a later stop. However, there are some inferences that can be drawn from this rule. If R exits at the first stop, then M must be the first stop:

PT55-Oct2008_LGE-G4_srd4.png

Similarly, if M is the last stop, R must exit at the last stop:

PT55-Oct2008_LGE-G4_srd5.png

Rule #3. This rules creates a simple sequencing relationship between V and J:

PT55-Oct2008_LGE-G4_srd6.png

Accordingly, V cannot be the last passenger to exit, and J cannot be the first passenger to exit, and we can create Not Laws reflecting those two facts:

PT55-Oct2008_LGE-G4_srd7.png

Rule #4. This is the most challenging rule of the game. The first part of this sentence creates a conditional relationship that indicates that if J is still on board when the van reaches F, then G must still be on board when the van reaches S. One representation for this portion of the rule is:

PT55-Oct2008_LGE-G4_srd8.png

Of course, the contrapositive for this portion would be:

PT55-Oct2008_LGE-G4_srd9.png

The second portion of the rule indicates that if J is not still on board when the van reaches F (J :longline: F), then G is not still on board when the van reaches S (G :longline: S), which can be diagrammed as:

PT55-Oct2008_LGE-G4_srd10.png

By combining the contrapositive of the first portion with the diagram for the second portion, we arrive at:

PT55-Oct2008_LGE-G4_srd11.png

This diagram means that the two conditions must always occur jointly. Conversely, if one of the two conditions does not occur, the other one will not occur either. In a nutshell, either both conditions happen, or both do not happen.

Because both the third and fourth rules contain J, an inference can be drawn linking J, albeit a tricky one. We will discuss this inference in the discussion for question #23.

The combination of the game scenario and four rules leads to the following final setup:

PT55-Oct2008_LGE-G4_srd12.png
 quiz555
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#1750
I am stuck on interpreting a rule from the 4th game on the October 2008 exam.

The rule states: Rosa is still on board when the van reaches Mineola.

Does this allow Rosa to get off at Mineola? If the van reaches Mineola and she is still on board than that is obviously satisfying the rule, but what if she is still on when it reaches and subsequently decides to get off at Mineola.

I assume that if she does get off at Mineola than she will not be breaking the rule since she was on board by the time it reached it.
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 Dave Killoran
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#1751
Hi Quiz,

Yes, your interpretation is correct. It would have been nicer if they stated this rule in a different manner (for example, they could have said "Rosa does not exit prior to when the van reaches Mineola"), but I'm sure they weren't too concerned that the rule is a bit confusing.

If you look at the correct answer to question #19, (E) shows Rosa exiting at Mineola, showing that R can indeed exit at M.

Please let me know if that helps. Thanks!
 Trinirican
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#3202
I am spinning in circles with Game 4 of October 2008.for questions 20 through 23, I managed to eliminate some answer choices, however I am not sure if there is something wrong with the way I am interpreting rules, or set up. Please HELP!!! :? If there is anyone who did this game before please explain.

Thanks
 Adam Tyson
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#3214
Happy to try! Let's just make sure we are talking about the same game, first - you're looking at the one with the four stops for the shuttle van? If so, here's the basic idea:

First, this is a linear game, as indicated by the rules that talk about who is before and after whom. Your base would then be the four stops, 1-2-3-4. It's an advanced linear game, with the two variable sets both going into that linear base - one variable set would be the stops (FLMS) and the other the passengers (GJRV).

The first rule is very straightforward - L is first or second. You can put a split option (L/ and /L) over 1 and 2, and you can also put not-laws for L under 3 and 4, if that helps. So is the third rule - J is on board longer than V (so V > J, with the accompanying not-laws for J under 1 and for V under 4).

The rest of the rules are a bit harder, and involve some careful reading and uncommon diagramming. Start with the second rule, R is still on board when the van reaches M. Some folks will mistakenly diagram that as M > R, but that's not quite right. You see, while R has to be on board when the van reaches M, there's nothing saying she cannot then get off at M. So, the rule really is saying "R is not before M" and could diagrammed "M (before/equal to) R" (try to imagine that's a "greater than or equal to" sign!).

The last one combines that same idea into a conditional setup, and I don't know how to draw it with my keyboard, but it's basically "If J is not before F then G is not before S." The contrapositive, then, is "if G is before S, then J is before F."

With those in mind, take another look at those questions and see if they make more sense now.

Adam Tyson
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 Trinirican
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#3221
Thanks a million! I did have the basic set up right with the not laws etc..but unfortunately I was one of those people who misunderstood the m r rule and diagrammed it the wrong way! I'm gonna try it again with the more than/ equal to set up. That should unlock it!
Thanks again!
 josuecarolina
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#7571
so, fortunately I just guessed D on the whole game and 3 out of 5 were D :-D

However, I have read over the explanations in the encyclopedia, and I just can't wrap my head around this game. I just can't keep track of the people and the stops, even when I set it up exactly like it is in the encyclopedia.
 Nicholas Bruno
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#7576
This is a very hard game, so most of your troubles surely stem from that fact. Let me try to diagram the game for you and I will explain what I do at each step. Let me know if it makes more sense:

First, this is an advanced linear game. So we need to have two levels: one for the "stop" and one for the "passengers." So it would start out like this:

Stops: __ __ __ __
Pass: __ __ __ __

I would diagram the first rule like:

Stop: L/ /L __ __
Pass: __ __ __ __

The second rule: R is still on board when the van reaches M:
M>= R (R can get off at M)
An inference we can make right away is that if R gets off at the first stop, the first stop is M
Also, if M is the last stop, that means that R gets off at the last stop

The third rule is diagrammed like: V>J

The final rule is diagrammed:
If J is not greater than F, then G is not greater than S
OR
G>S <---> J>F

Let me know if this helps you out!
 josuecarolina
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#7577
thanks for trying...I want to say, I would probably have gotten them all wrong if I had not guessed...I didn't really 'get' the D answer questions.

And my diagram matches Powerscores. But somehow, when I come back to it after a day or 2, with the right diagram, I still can't track the passengers and the stops.

Thanks!
 Nicholas Bruno
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#7578
If you are getting confused with the variables, try writing them out on the top of your diagram. For instance, you can do something like

Group 1: A, B, C, D
Group 2: E, F, G, H

It may just help your memory during the game to write them out before hand.

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