December 2007 LSAT Section 2 Question 6

Which one of the following could be the order in which the designs are presented, from first to last?

shubbyaluk on August 30, 2016

Deduction from "No -sandwich" sequencing rules

Hey all, Please see the rule below and kindly share your thoughts: "Green's design is presented either at some time before Jackson's or at some time after Liu's, but not both" 1. Do the following deductions always follow from the rule above? Either G<J,L or J,L<G 2. Is this a frequent deduction that is tested on the LSAT 3. If the answers to both questions above are yes, can I automatically make the deductions above and save time if I see a similar rule in a game such as Preptest 52, Game 2?

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Mehran on September 1, 2016

@shubbyaluk let's breakdown the 2nd rule here:

"Green's design is presented either at some time before Jackson's or at some time after Liu's, but not both."

This is "either/or" so we need to identify our two variables first:

(1) G > J from "Green's design is presented . . . some time before Jackson's"
(2) L > G from "Green's design is presented . . . some time after Liu's"

Now we pick one, negate it and make that our sufficient condition, the other variable is our necessary condition:

J > G ==> L > G
G > L ==> G > J

Now let's address the "but not both" part of the 2nd rule.

"Not both" is treated just like "No As are Bs" so we need to pick a variable and make it our sufficient condition, the negation of the other variable is our necessary condition:

G > J ==> G > L
L > G ==> J > G

As you have correctly pointed out, this means that either J & L > G or G > L & J.

However, we would not recommend assuming anything on the Logic Games.

Take the time to diagram the rules and make the deductions. Given that you have seen this before, it won't take you very long.

Hope that helps! Please let us know if you have any other questions.

Anna20 on July 20, 2020

I've watched the video, but unfortunately not sure I've followed the process for diagramming either/or and not both. My understanding was to diagram this rule as:

J - G - L
G - L - J

I am not sure where I am going wrong here. Or how you get to either J & L > G or G > L & J?