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# PT16.S1.Q01 - eight new students

Alum Member
edited March 2017 1008 karma

Hi I was just watching JY's video on grouping games set up 1.

https://7sage.com/lesson/grouping-game-1-game-board-setup/

I'm wondering why "neither nor" in rule 3 is interpreted as not both, as in S -> /Y , and W->/Y.
Why can't it be interpreted as biconditional? S <-> /Y as in S and Y are always apart.

Is it because unlike the in-out games, a biconditional in this a grouping game means that if, for example, Y is not in 1,then S must be 1? (which would be an incorrect inference given that there are more group options now)
If that's the case, if this game was an in/out game, could I still interpret the rule as a biconditional?

• Alum Member
edited March 2017 1008 karma

any help would be greatly appreciated!

• Legacy Inactive ⭐
edited March 2017 4141 karma

Rule 3 is interpreted as S--->/Y and W---->/Y because the presence of S or W means that Y cannot be there. The same is true for the presence of Y, meaning S cannot be there and W cannot be there (Y--->/S and Y--->/W).

Yeah in a sense you could consider treating it like a bi-conditional, but only when there are two groups. Generally writing it out as such will give you trouble in this game because there are 3 classes. If you write S<---->/Y it would also mean that /Y---->S which is a sufficiency necessity error of the contrapositive of S---->/Y which is Y---->/S not /Y---->S which is part of your bi-conditional statement. Using the bi-conditional in this game will get you into trouble when you want to place S or W because /Y does not trigger S or W. Basically you can interpret it as a bi-conditional only if you have two groups (if the last rule in the game applies and you fill up class 1) and have placed S or W because there is only one place for Y to go without failing the 3rd rule.

• Alum Member
1008 karma

@"nessa.k13.0" ah! That's very clear. Thank you!

• Legacy Inactive ⭐
4141 karma

@TheoryandPractice you're welcome!