## Logic Chains Bi-directionality

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*Ari*

Posts: 47
Joined: Sun Dec 05, 2010 1:20 am

### Logic Chains Bi-directionality

Hi,

Posted this on ManhattanLSAT forums too, but haven't got a response yet. So, I figured I would try here and see if anyone is familiar with their Logic Chain method (seems to kick butt if you aren't btw)

Just a question. I've been practicing using the logic chain for binary grouping games, but I seem to find myself confused, as to when an arrow should be bi-directional. In most circumstances, I understand that it's a single arrow when it says something like 'Jon and Tina cannot both be selected'.

Does the bidirectional apply on those constraints only when they both have to be selected into a group?

Cheers!

Manhattan LSAT Noah

Posts: 744
Joined: Tue Oct 12, 2010 8:43 am

### Re: Logic Chains Bi-directionality

Sorry we didn't respond over there yet - but I'm sure someone will soon. In the meanwhile, you're right that there's a type of situation where a simple, X and Y can't be ".." statement will mean bi-directionality. It's in a situation like this: You are either placed on volleyball or soccer, but not both. Kim and Jared cannot play the same sport.

There are other, even rarer situations where bi-directionality comes up, Like with "if,and only if" as well as when two rules combine to create that.

I hope that helps.

- N

*Ari*

Posts: 47
Joined: Sun Dec 05, 2010 1:20 am

### Re: Logic Chains Bi-directionality

Manhattan LSAT Noah wrote:Sorry we didn't respond over there yet - but I'm sure someone will soon. In the meanwhile, you're right that there's a type of situation where a simple, X and Y can't be ".." statement will mean bi-directionality. It's in a situation like this: You are either placed on volleyball or soccer, but not both. Kim and Jared cannot play the same sport.

There are other, even rarer situations where bi-directionality comes up, Like with "if,and only if" as well as when two rules combine to create that.

I hope that helps.

- N

Thanks for the help. I have one more question and then I should be good, at least for this specific question. What about in games, where entities are selected or not selected? Is it only a single non bi-directional arrow in these circumstances because they don't have to belong to one group or the other?

Is there a good rule of thumb to determine when an arrow should be bi-directional or not?

Once again, I greatly appreciate the help!

Manhattan LSAT Noah

Posts: 744
Joined: Tue Oct 12, 2010 8:43 am

### Re: Logic Chains Bi-directionality

You're right that usually these conditional relationships go in one direction only. The bi-directional ones are more common with the games where the entities must go to one group or another (versus selected/not selected), but they're still rare. I'm afraid there's no rule of thumb that comes to my mind, but most arrows go in one direction, so just keep an eye out for the bi-directional situations we discussed above.