PTB.S2.G2 - A park at most five of seven kinds...

evanescence

Hey!
Can someone please explain how to interpret rules 3 and 4 of this LG? (PT B, S2, G2)

3: "If y is not in, then either L or O, but not both are in"
How I interpreted this rule:
Not Y --> L or O
Contrapositive:
Not L and Not O --> Y

4: "If it's not the case that the park contains both L and O, then it contains F and S"
How I interpreted this rule:
Not L and Not O --> F and S
Contrapositive:
Not F or Not S --> L or O

In the explanation video, JY has a world where L, O and Y are all in, and I don't understand how we got there. I'm sure I'm missing some kind of bi-conditional lesson, or something. Did he just "negate" rule 3 by just the wording like: "if L and O are both in, Y is in," and that's how we got a possible world where L, O and Y are all in? Please help me lol

Admin Note: Edited title. Please use the format: "PT#.S#.Q# - brief description of question”

AlexLSAT.

In order to trigger a conditional.. you have to hit the sufficient condition. The rule says /y > L or O, but doesn't say anything about what happens when Y is in. Simply put, Y being in doesn't trigger rules 3 or 4 so there is a world in which Y L and O can all be in.

evanescence

Thank you @AlexgLSAT !!!