Linear Setup Practice Drill #8

[getsmart]

Re: Linear Setup Practice Drill
(Question #8 )

Please help me understand why "placing O on 4" causes a violation of the third rule"!

I understand everything else and my setup matches the answer key's (sans the O Not Law on 4). I just don't get it!

[Dave Killoran]

Hey getsmart,

Thanks for the question--the inference you’ve asked about is a difficult one. I see that you are using a somewhat old version of the book, and the newer editions of the book actually explain this inference in greater detail (and also add about 130 more pages to the book!). I also posted an explanation of this inference on the book website (see page 2 or 3 of your book for the website address). Here's why O can't go on 4:

When O is placed at Table 4, then Tables 1, 2, and 3 must each occupied by a patron. This forces the Empty table (variable “E”) to be assigned to Table 5, 6, or 7. Unfortunately, that assignment is a violation of the third rule that states that tables 5, 6, and 7 must be occupied by a patron.

Whenever you see a Not Law that doesn't make initial sense, try placing that variable in that position and see what happens--that often makes it easier to understand why the variable can't be placed in that slot.

Does that help explain what you are seeing? Please let me know. Thanks!

[getsmart]

Got it!!!

Thanks so much!!

[Dave Killoran]

Anytime--glad to help