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Nactations of 61P-62R-52S-22N-32 — 2011 Update

Posted By: Nack Ballard
Date: Saturday, 24 December 2011, at 2:47 a.m.

In Response To: Nactations of 61P-62R-52S-22N-32 — 2011 Update (Taper_Mike)


1O '1O2X '3X '3X ' '2X3O

1X ' ' ' '5O2O3O1X ' '3X


In my post (that Mike updated in his well-researched and articulate manner), I had given the following Nactations (in answer to inquiries):

    24/22 6/3 is E
    24/22 13/10 is S, Z or B
    24/22 8/5 is C or @
    8/5 7/5 is P or 5
    7/4 6/4 is p or 4
    13/8 is T
    6/1* is H

Since the time of that post (July, 2010), definitions have changed or been refined such that the Nactations in red (B and 4) are no longer in vogue.

As Mike spelled out in his B/S/Z table, B refers to a move in which the near-side half of the play is made within the outer board: portions originating from the midpoint or elsewhere in the far outer board do not qualify. [For example, 43D-42P-61B is 24/18 10/9.] Notwithstanding, I consider B acceptable (above) for 24/22 13/10 by default when no legal B play actually exists because it areally resembles half of a B doublets play, so if someone uses it under those circumstances for non-doublets that's what it means (and it can even be programmed as a default usage). Even with that caveat, though, S or Z is greatly preferable.

[Another example of default usage is 52S-61P-65 played 22/11. Granted, this play is nactated S, and R is supposed to be confined to the faR side. However, I'd rather have R mean 22/11 in that case (by default) than mean nothing.]

Mike carefully avoided mentioning numerals because he knows I have them under review. Specifically, what is under review is (1) whether to apply the outer board wrinkle for numerals, and (2) whether the 4pt, 14pt and 24pt should be ranked or treated equally before applying the hit/points/6 rule. Neither of those reviewable aspects affect the use of "4" in the position above; it is 8/5 6/4 regardless, technically. Still, that play is so much worse than 7/4 6/4 that if a human wrote "4" here I would most likely believe the nactator to be assumptively communicating 7/4 6/4.

Finally, this seems like a good time to update bgonliners about a detail regarding @ that Mike spotted in the annactated game of January 2011. For the seventh position there (21S-41S-22m-31@-21B-52T-21), @ was properly used for 24/22 23/22. However, though it didn't affect the play, I stated in the notes, "Be aware, too, that the definition of @ includes the dedication clause (like P does)..."

Well, guess what; @ doesn't anymore -- not quite. Not long after the annactated game post, I upgraded the clause for @ to "dedicate to the extent possible." You must use as many portions as you legally can to create an anchor, then apply the hit/points/6 rule.

Consider this situation that Dmitriy recently asked me to nactate:


1O1O ' '2X4X2X2X ' ' '4O

 ' ' ' ' '5O2X3O ' '1O3X

31P-21S-66B-11


The standout play is 24/22 23/22 6/5, and the areal Nactation for it is E (third member of the underlined E family). However, I recommended @ (anchor). Blue uses three aces to anchor on the 22pt, and to the fourth ace 6/5 we can apply the hit/points/6 rule. This very useful Nactation option would be denied if a rigid dedication clause were implemented instead of "dedicate to the extent possible."

[Assumptive usage is also allowed: @ can mean make an anchor and do what's obvious with the rest of the roll. However, like using assumption with any character, it should be applied only, if at all, when the best anchoring play is an overwhelmingly better backgammon move than the other anchoring plays.]

P, on the other hand, is better off with a strict dedication clause, else I foresee there being too much temptation to overuse the P family rather than learn the appropriate Nactations. In the feature position (at the top of this post), for example, it would be annoying to see italic P used for 24/22 8/5, or for someone to use first member P for 24/22 8/5 thinking that hit/points/6 is the main determinant for all point-making plays (ranking most points above full dedication). In the case of P, restriction is better for the sake of simplicity.

By contrast, anchoring (@) has a much more limited utility (than P) and some leeway can be beneficial — as the 31P-21S-66B-11@ example (diagrammed just above) demonstrates.

Nack

P.S. For anyone who might not have noticed, I am now calling the hit/most/6 rule the hit/points/6 rule — as it will be worded in the updated tutorial. They mean the same thing. (For the "most points" convention, I'm just making "points" the key word instead of "most.") I'm hoping to gradually phase out the former term in favor of the latter, but not at the cost of it being a stumbling block, so... feel free to use the terms interchangeably.

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