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Nactation question

Posted By: Nack Ballard
Date: Wednesday, 25 November 2009, at 3:46 a.m.

In Response To: Nactation question (Petter Bengtsson)

I see you're using the letter e (each) for 11 played 24/22 6/5(2). Before seeing that I would've guessed to use the letter S (split). Make the five point with the first two aces is obvious, and split with the last two aces.

Would you say that using S is clearly wrong?

Great question. The answer that follows is long, but please keep in mind that complex doublets (i.e., where three or four subparts of the play differ and the move is played in two or more quadrants) involve by far the most subtle concepts that exist in Nactation. The vast majority of plays that arise are easy and straightforward.

“S” is acceptable for 24/22 6/5(2), using assumptive Nactation (in Section 6 of the tutorial) as you did. “S” has the advantage that it immediately suggests Split (Section 1), whereas “E” does not appear until Section 3, and lower case examples are not yet provided.

“E” means that half of the play is made in Each inner board. When more than one such play exists, "e" is the one that doesn’t anchor. For example, 54D-22E or 41\$-22E is 24/22(2) 6/4(2), whereas 54D-22e or 41\$-22e is 24/20 6/4(2). [One of those plays has an incidental hit.]

There is a slight risk that if you write “41\$-11S,” someone will think you mean splitting to the 20pt (even though S shouldn’t be used that way -- proper is H or U if it hits and U if it doesn’t). He will probably realize you would have used H for the hit and deduce your intent, but it’s good to be aware of potential misinterpretations.

I prefer “e.” The main definition of S in Nactation is two-pronged: a play that splits (or moves on the far side of the board) with one checker and comes down (or plays within the outer board) with the other. Your one-pronged definition of S is a feasible option, but there is almost always a clearer alternative.

For 31P-32S-22, assume (the obvious) point-on-the-4pt as an unstated part of the play. Does “S” mean that the other half of the play is 24/20 (one-pronged) or that it is 24/22 13/11 (two-pronged, as is usual)? Instead, using “e” for the former (and M for the latter), thereby describing the entire play, avoids ambiguity. (For that matter, even 21S-11S could arguably be 24/23 8/7 6/5(2).)

In any case, without an overriding reason, global consistency is preferred. 41\$-22e is similar in play type to 41\$-11e; and 31P-32S-22e is similar to 42P-43S-11e. Indeed, if we factor out whether and where some moves hit, the actions are all fundamentally similar; it seems natural to use the same letter for all four plays.

[Occasionally, I have to resort to 11S instead of 11e in file names. Example: for 21S-11, e is best but E isn’t terrible. Building on these, I have rollouts for both third roll positions of 21S-11e-11 and 21S-11E-11. Unfortunately, most operating systems (including Windows) are case insensitive for file names. I changed the one with the lower case e to 21S-11S-11 (rather than something like 21S-11ee-11). This situation is rare, however, and I still call the position 21S-11e-11 despite the substitution in the file name.]

Nack

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