by SamanthaW170 Mon May 28, 2018 1:40 pm
One of the rules for this game is that if L is not on Saturday, then L comes before F. The contrapositive of the statement is: If L is not before F (in this game, F-L, since F has to go in the beginning of the week, where it's not possible for two librarians to go on the same day), then L is on Saturday.
From the tree diagram, we see that there are four elements which have to go later in the week than F (and each has to go later in the week the one proceeding it on the chart): K-Z and M-G. This led to me conclude that F can only go on Monday or Tuesday, since K-Z and M-G need to go one each on Wednesday-Saturday.
From the diagram, we see that the only two librarians who could be on duty on Monday are F and H, since all other elements have at least one other element proceeding them.
I was thinking about these inferences, since both involve F, when I realized that if I am correct, is it ever possible for L to go before F? In other words, if F always has to go before L, then isn't L always on Saturdays?
Since the only option for the Monday librarian is F or H, if we put H first, F has to go on Tuesday, since it cannot go on Wednesday-Saturday. There would be no room for L before F.
It seems highly unlikely that a conditional rule could only play out one way in a game on the LSAT - where am I going wrong?