PTB.S2.G2 - trees in the forest

calftemp

https://7sage.com/lsat_explanations/lsat-b-section-2-game-2/

I have some questions about the proper diagram and meaning of a rule in this in/out game.

Rule 3: "If Yews are not in the park, then either L or O, but not both, are in the park."
- Could someone explain about how to properly diagram this rule (ideally in notation that does NOT involve biconditionals)? I diagrammed it as 2 separate rules (shown below), but I think it only confused me more...
/Y --> L or O (representing 'either/or')
/Y --> /L and /O (representing 'not both')
- If I'm understanding the meaning of this rule correctly, does the contrapositive of this rule basically mean/state that "if both L & O are in the park, then Y is in the park." ? Does the contrapositive of this rule also include "if both L & O are OUT, then Y is IN"?

TIA!

runiggyrun

I think JY diagrams it as /Y-->(/L<-->O)
Alternatively you can diagram it as /Y-->(/O<-->L), which is the same exact thing, just showing the contrapositive of the embedded conditional.

I like having the rule in one place as opposed to separate lines, because as soon as I see /Y I know I need to trigger the relationship in parantheses.

If you're not comfortable with the biconditional you can also notate it as
/Y-->L/O (where L/O is supposed to be whatever your notation is for "L and O are not together". For me I put them in a vertical box with a slash through, but I can't do that in this text box, so I typed them as L/O).

And you are right, the contrapositive states that if you have both L and O in or both L and O out then Y has to be in.

This might be one of the instances where it's worth writing down the contrapositive.
I'd write it as
LO -->Y where "LO" are supposed to be on vertically on top of each other and boxed to signify they are together.
I hope that's clear enough.
Essentially, Y out triggers L/O apart and LO together triggers Y in, however you want to notate it.