Hey David —
I think your understanding of how the rule works is correct, and I think the confusion is caused by the general way in which we’ve set up the game —
For this game, there are two possible outcomes for the participants — varsity or junior varsity — for the notations, my suggestion is to notate this as a selection, or in/out, game, so that getting selected for the varsity is “in” and getting selected for junior varsity is “out” — you can also think of not being on varsity = being on junior varsity, and not being on junior varsity = being on varsity.
So, per that way of setting things up, N on varsity would be notated with a simple N, and N on junior varsity would be notated with an N crossout (meaning he is not on varsity) —
So, that rule reads “If N is selected for JV, O will be too.” —
You could have thought of this as Njv -> O jv, and crossout of O jv -> crossout of Njv, and that would have been correct as well, but –
Again, per the way we’ve set up the game (with N crossout meaning N jv) along with the inference that not being on jv means being on varsity, we end up with the way I notated it in the book:
/N -> /O, and O -> N.
Hope that makes sense — I realize that this situation is pretty much the textbook example of a complicated double-negative, and it’s tough to explain in words, so if I haven’t done a good enough job / if you have any follow-up, just let me know —