PT20.S3.G2 - a university library budget committee

benjipantsbenjipants Member
edited May 2016 in Logic Games 65 karma
"Diagramming on Gameboard: Two ‘not both’ Conditional Statements with Common Necessary Cond."

Hi 7Sagers,

In this game: https://7sage.com/lsat_explanations/lsat-20-section-3-game-2/

We have N ---> to both R and S

Why, when J.Y. fills up one of the ‘out group’ slots on the gameboard, does he say that "it doesn’t matter" of you fill the slot with N/R or N/S? I’m not sure I understand how these two conditional statements with a common necessary condition interact with each other. One of N/S AND one of N/R have to be in the out group, yes?

Thanks!

Bonus question: I’m also wondering why it’s best to solve this game by filling in the game board as J.Y. does, as opposed to filling in three slots for the L/M/R variables (two in, one out), or even splitting into three game boards, each with a single of those three variables out.

Comments

  • Accounts PlayableAccounts Playable Live Sage ⭐
    3107 karma
    Since N implies both R and S out, N has a not both relationship with R and with S. Thus, depending on the relationships to the other rules, at least one of N/R and N/S must be out (maybe N, R, or S are all out, maybe only RS are out, etc). However, if you were to put both N/R and N/S into two of your out slots, you would be double counting N since N is common to both; this makes the game board confusing since you have to then mentally keep track of whether N is being double counted or not. In my opinion, that isn't a great use of your mental resources. When JY means by "it doesn't really matter" is pick one of N/R or N/S to be in your out slot; that way you know that one of your out slots is filled, and it doesn't add the confusion of double counting N.

    As to your second question, I haven't done the game, but splitting the board is a preference that varies game to game. Some people may decide to split boards on a game while other won't and neither group sacrifices time or accuracy. In other words, JY's decision to split or not split isn't necessarily the best way to do the game. A thing that has helped me immensely on games is to try doing the games like how JY does them and then redo the game for practice later using a different method. Implement whichever is better.

  • benjipantsbenjipants Member
    65 karma
    Hey AP, thanks for the response.

    I did understand the idea of not wanting to double-count N.

    But it does seem like if one is going to put this information on the game board, it should be N/[R/S]. Wouldn't that be a more precise notation? N has to take up a slot, or else one of R or S has to take up a slot. If you only put N/S or N/R, you are leaving out a possibility!
  • J.Y. PingJ.Y. Ping Administrator Instructor
    14195 karma
    @"Accounts Playable" Great explanation and thanks!

    @benjipants I like your notation. N/(R/S) is more accurate. But doesn't it still leave out the same possibility? Like for example, if R is the item that's out. That seems to satisfy the notation. But you still have to remember that there's a not both relationship between N and S and that means at least one of N or S has to be additionally out. How's that different from having written just N/R in the out group originally?

    I think the point of making notations like this is to count the items, as @"Accounts Playable" pointed out. Your game board's out group is limited to 3 items only so you really want to fill that up because it yields the giant inference that everything else goes in. That's the main point of the space fillers in the out group.
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