This is an explanation of the second logic game from Section II of LSAT Preptest 74, the December 2014 LSAT.
Four art historians, namely Farley, Garcia, Holden, and Jiang (F, G, H, J) will each give exactly one lecture from four different topics: lithographs, oil paintings, sculptures, and watercolors (L, O, S, W). The lectures will be given in sequence with each art historian giving a lecture on a different topic. You must determine the possible sequence of the lectures and the assignment of topics to speakers.
This is an unusual linear game. It’s unusual because it has two different groups, and some of the ordering rules cross over between groups.
Here’s how to set up the main diagram:
The first rule says that O and W are before L. So far, that’s standard:
It’s the second rule that’s confusing. This rule says that F is before O:
Why is this confusing? Because F is a lecture, and O, W, L are subjects. So F and W could actually be in the same spot, like this:
As long as you remember that F and W can go together, this game is easy. Otherwise, it’s hard, and it’s best to draw the O, W, L and F, O rules separately, like this. Then you can check them separately to rule out violations:
If you can handle the ambiguity, it’s cleaner to combine the rules. Just remember that F and W are different types of variables and could go together:
The final rule is about speakers. H is in front of G and J:
Finally, the sculptures lecture is random, it has no rules:
There are a couple of up front deductions. We can say which lecturers go where:
- F has at least two people after it: those that lecture on O and L
- H has at least two people after it: G and J
This means that both F and H can go second at latest. That’s the only way to leave two spaces after them:
The line under F and H means that the two variables are reversible.
Since F and H go first and second, G and J go must go third and fourth:
Again, the lines underneath the letters mean they’re interchangeable.
This deduction about FH and GJ makes it much faster to draw diagrams. You should always take some time to examine your setup for small deductions like this before moving on. This is the key to going fast on logic games.
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