Grouping Games Rule Diagramming Drill 5-97

[kirstenjm3]

Hi, I'm wondering if someone can explain to me why question/rule 2 uses a not block and question/rule 5 uses a double not arrow for the variables. Is this difference solely because of the amount of variables present? Could I diagram question/rule 5 using a not block?

Thanks!

[Ron Gore]

Kirsten,

The reason for the difference is that there is no efficient way to diagram the rule "W, X, and Y cannot all be selected together" using a Double-Not Arrow, although you could diagram it using Double-Not Arrows. To do so, you would have to say:

W
+ not Y
X

AND

W
+ not X
Y

AND

Y
+ not W
X

That doesn't make a lot of sense to try to diagram when you can more easily use a Not Block to show that you can't have all three together. Any benefit of using the Double-Not Arrow is overcome by the relative of using the Not Block in this particular instance.

However, for Drill 5, in which the rule is simpler ("R and X cannot be selected together"), the benefits of using the Double-Not Arrow make that diagramming technique the better choice. Most people find that they have an easier time linking conditional rules and gaining inferences using the Double-Not Arrow than Not Blocks for rules such as this.

Please let me know if that helps.

Thanks!

Ron

[kirstenjm3]

That helps! Thanks, Ron.