Game #4 (December 1991 Question) Set up

[mtp39]

Hello,

I felt pretty comfortable with my setup until I saw how many questions I got wrong and looked at the answer key to see a series of "key deductions from the two-value system that exists for reach of the three choices for cars on each floor." Would you care to elaborate further on this two value system, when it comes into play, and how we should identify it?

Thanks,

Michael

[Lucas Moreau]

Hello Michael,

The two-value system is just referring to how all of the attributes the cars in this game can have are one of two values. They're either new or they're used, either production models or research models, etc.

Mainly, the key deductions from the two-value system are deducing that if a vehicle is not one of the two values, it must be the other. For example, the rule that says that there are no used research models can be portrayed as:

If a car is used, it is not a research model.

But since there is a two-value system, if the car isn't a research model, it must be a production model. Therefore:

If a car is used, it is a production model.
OR
All used cars are production models.

This deduction allows you to conclude that, for example, the cars on the third floor are production models, since the last rule tells us that the cars on the third floor are used. The book gets into other examples of this, but feel free to ask for more help if you need any. That's why we're here!

Hope that helps,
Lucas Moreau

[vas]

Hello,

In Game 4, when I initially saw the rules "The exhibition includes no used research models" and "The exhibition includes no research models that are sports cars," I thought these were Not-Blocks instead of conditional rules (i.e. double not-arrows). For future games, how can I make sure I'm dealing with conditional rules and rather than Not-Blocks?

Thank you in advance for your help!

[BethRibet]

Hi Vas,

Thanks for the question. The phrasing indicates that the two conditions are mutually exclusive -- meaning used and research never go together, and sports and research never go together. That's how you can tell these are "double not-arrows".

As far as "not-blocks", it's not really either/or, it would be true that if there is research, there is not sports, for instance. But you still want to take note of the mutually exclusive conditions.

I hope this helps!

Beth

[vas]

Thank you, Beth!