A child must play five games example

[gpreiser]

I keep confusing myself with the diagrams that I'm making where I fill in letters in spaces to show that the letter *can* appear in those spaces but not that those are the *only possible* letters that can fill those spaces. Do you have any tips for how I could diagram differently so I avoid confusing myself when I later refer to the diagram?

Here's an example - P. 82 of LG Bible had a q that says:

A child must play 5 games - P Q R S and T - one after another, not necessarily in that order. The games must be played according to the following conditions:
. The child plays exactly two games between playing S and T, whether or not S is played before T.
. P is played immediately before Q is played.

On the top of page 83, we end up with a diagram that shows "R/" and "/R" in spaces 1 and 5 respectively. The problem I have is that when I go back to refer to this diagram in the thick of the game, I get confused as to whether it is saying that these spaces could have R as a possibility, or that R is the *only thing* that can appear in either of these spaces. The latter interpretation is wrong, but when I look at the diagram I forget that other letters can appear on those spaces too -- like S and T. But then if I try to draw S and T into those spaces as well, the whole thing just ends up more confusing. Do you have suggestions for an alternate diagram I could use?

Thank you!

[Dave Killoran]

Hi G,

Thanks for the question! the simplest answer here is that you aren't clear on what the rule representation means. So, if you can lock down on that, it should clear this problem up quickly. this is especially true because you know it's an issue, and thus you can make sure to give it a bit more emphasis both in practice and during actual LG sections.

For example, if I see "A/B" in a space, then I know it's A or B that goes there. But, if I see "A/ " that tells me that it is one possible spot for A (and I'd expect to elsewhere see " / A" as that is the other "half" of this rule representation), and that the blank after that slash means any other variable (within rule limitations) can go there. If you can understand block and sequences, etc, you can pick up this notation as well. You just have to focus on learning what each representation means.

Simple rules:

• 1. If a slash is use ( / ) and one side is "open," other variables can go there ("A/ " means A can go there and most likely in one other spot (marked by " /A"); but other variables can go there too).
  
  2. If neither side of the slash is open, then one of those variables has to go there (A/B means A or B goes there; A/B/C means A, B, or C goes there, etc).

That shoudl be a start! Please let me know if that helps. Thanks!

[gpreiser]

Thanks Dave! But I still get confused because if I see "N/" and "/N" in spaces 2 and 6, for example (FYI I'm looking at p. 154 of the LGB), I don't know of that means that N is the *only letter* that can go on either 2 or 6, or whether N *or any other letter* (without a not law, of course) are possibilities for spaces 2 an 6. How can I clear up this ambiguity in my diagram? Thank you!

[Nikki Siclunov]

Hi G,

Assuming the game is Balanced, it would be impossible for N to be the *only letter* that can go on either 2 or 6. If that were true, and N cannot be used twice, you'd end up with an empty space in either 2 or 6.

The meaning of the Split Dual Option is: N must be either 2nd or 6th. This is why N is in front of the slash in 2, and after the slash in 6 (it's as if we took N/N and split it between the two spaces). Absent any applicable Not Laws, this rule would not prohibit other variables from being either 2 or 6. The point is, if N is in 2, any other variable can be in 6 (in accordance with the rules, of course), and if N is in 6, any other variable can be in 2 (again, in accordance with the rules); if another variable ends up in 2, N must occupy 6, and if any other variable ends up in 6, N must occupy 2.

Please let me know if this helps!