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attorneysomerville
Free Trial Member

The "/A->B" rule is so important for grouping games that PowerScore uses a special symbol ("A<-|->B", or "the double-not arrow") to note it. As a person who understands how important this is for grouping games, I think the "double-not arrow" is brilliant. As a person who has tried to explain it to others, it is both frustrating and confusing. The "double not arrow" is ONLY used when the sufficient term is negative and the necessary term is positive--or is it the opposite? It makes a huge difference, but I find it almost impossible to keep it straight in my head, much less explain it to someone else. For that reason, I think JY is wise to avoid using it here at 7Sage.

But what if it were not confusing? I have come up with TWO arrows that practically write themselves and make grouping games much easier. All you have to do is look at the way we write out "/A->B" and "A->/B."

Note how the slash comes first in the "/A->B" situation, but comes second in the "A->/B" case. Let's turn those slashes into pictures. If we put the forward slash first, we can make a "/\" picture. If we put it second, we get a "\/" picture.

/A->B turns into A<-/\->B

A->/B turns into A<-\/->B

Pictures are helpful if they mean something, so let's call the "/\" picture an "erupting volcano." The "erupting volcano arrow" means that something is erupting, so that something must be in your slot. The "\/" looks like a "leaky funnel," which means something is leaking, which means something must be OUT.

If you can remember that "slash comes first" means "/\," and "/\" means "erupting volcano," and "erupting volcano" means something must be in, you can turn a "/A->B" rule into a full slot within seconds. And if you can remember what a "leaky funnel" does, you'll fill an out slot just as fast.

And there's no reason to ever get them mixed up!

But what if it were not confusing? I have come up with TWO arrows that practically write themselves and make grouping games much easier. All you have to do is look at the way we write out "/A->B" and "A->/B."

Note how the slash comes first in the "/A->B" situation, but comes second in the "A->/B" case. Let's turn those slashes into pictures. If we put the forward slash first, we can make a "/\" picture. If we put it second, we get a "\/" picture.

/A->B turns into A<-/\->B

A->/B turns into A<-\/->B

Pictures are helpful if they mean something, so let's call the "/\" picture an "erupting volcano." The "erupting volcano arrow" means that something is erupting, so that something must be in your slot. The "\/" looks like a "leaky funnel," which means something is leaking, which means something must be OUT.

If you can remember that "slash comes first" means "/\," and "/\" means "erupting volcano," and "erupting volcano" means something must be in, you can turn a "/A->B" rule into a full slot within seconds. And if you can remember what a "leaky funnel" does, you'll fill an out slot just as fast.

And there's no reason to ever get them mixed up!

## Comments

So for "~A→B", this is equivalent to "~~A or B", which is in turn classically equivalent to "A or B". This means at least one of A and B must be in.

And for "A→~B", this is equivalent to "~A or ~B". This means at least one of A and B must be out.

This is simpler than having to remember another mnemonic and involves a deeper understanding of how the LSAT treats conditionals.

Bottom line: there's a trade-off between fast and simple. People who use flashcards are trying to get their speed up by exchanging a thought process for instant recognition. I PREFER working out the logic in my head, but I only have 35 minutes on a logic game section, and a fast, reliable mnemonic may have its advantages.

Having said all that... I love your explanation of the "NOT A or B" mode, and I'm going to try it out with some guinea pigs. If I can explain that effectively, I'll gladly use it instead of a new mnemonic. If I can't, though, I think I'll stick with my "erupting volcano" and "leaky faucet" pictures.

So... thinking this out... I read "/A->B," and I write down "A/B." I read "A->/B," and I write down "NOT [AB]." Right?

Admin edit: You know why I edited this. Last warning.

The powerscore bibles didn't do anything, but confused me even further... I really wished I had started out with the 7Sage curriculum from the beginning.

Clear and Simple learning = success!