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Nactations of 63R-42P-43 — 2011 Update

Posted By: Taper_Mike
Date: Saturday, 17 December 2011, at 9:18 p.m.

In Response To: Nactation after the initial moves (Andreas)

Due primarily to an evolution of the 6pt Convention into the more comprehensive Hit/Most/Six Rule, many of the Nactations given in this thread are now obsolete. This post describes the current Nactations for all of them. In most parts of the board, the destinations of checkers that are moved in a play are preferred when blots and spares are moved as close to the 6pt as possible. Blot and spare destinations in a player's outer board, however, are preferred when the one closest to the 6pt is as far back as possible. For a step-by-step instructions in the application of Hit/Most/Six see the Procedural Description. Another big change is the general definition of playing down. Originally, that meant playing one or two checkers down from the midpoint. Today, playing down refers to a move made to or within the outer board. The checker must land in the outer board on the near side, but can be moved from any point in either outer board. These two refinements work together to give precedence to plays that pick up blots in the far outer board, and move them to the higher points in the outer board. Backgammon-wise, that is often a good thing to do. The position under discussion in this thread is given below. Andreas suggested the position, and several candidate plays for analysis. It's a case of the good, the bad, and the ugly. Nactations for all are under consideration. 63R-42P-43 Position ID: mGfwATDgc/AJIA Match ID: cIkRAAAAAAAA In the Nactations that follow, moves in different parts of the board are categorized using the terms far, down, jump and inside. Each die is treated separately, so that in a roll of non-doublets, there are two moves, and in a roll of doublets, there are four moves. Here are the definitions. Far — The entire move is made on the far side of the board, including entering a checker from the bar. The checker can land anywhere on the far side, from the midpoint on up. Down — A move made to or within the outer board. The checker must land in the outer board on the near side, but can be moved from any point in either outer board. This is the definition that was given above. Jump — Jumping over the bar means moving a checker from a point in the outer board, and landing on a point in the inner board. Inside — A checker is moved entirely within the inner board, including checkers that are borne off.

D (Down) Family

Traditional Notation	Far 0	Down 2	Jump 0	Inside 0	Hits on These Points (more is better) (higher is better)	Owned Points Not Held by All Members in Family (more is better) (closer to 6pt is better)	Blot and Spare Destinations (closer to 6pt is better) (outer board: farther is better)	Nactation
15/11, 13/10		15/11 13/10					10pt* 11pt	D
13/10, 13/9		13/10 13/9					9pt* 10pt	d
15/8		15/11 11/8					8pt*	D

^*This is the deciding criterion.

O (Outer) Family

Traditional Notation	Far 0	Down 1	Jump 1	Inside 0	Hits on These Points (more is better) (higher is better)	Owned Points Not Held by All Members in Family (more is better) (closer to 6pt is better)	Blot and Spare Destinations (closer to 6pt is better) (outer board: farther is better)	Nactation
13/6		13/9	9/6				6pt*	O
15/11, 8/5		15/11	8/5				5pt 11pt*	o
13/9, 8/5		13/9	8/5				5pt 9pt*	O
13/10, 8/4		13/10	8/4				4pt* 10pt	o

^*This is the deciding criterion.

Moves in the related families B (Both), S (Split) and Z (Reverse split) move checkers according to the descriptions in the table below. In the position above, the B (Both) and Z (Reverse split) families are both empty. Definitions: B (Both), S (Split) and Z (Reverse split) Family Non-doublets Doublets B One die is played on the far side, and one die is played entirely within the outer board (on the near side). Two dice are played on the far side, and two dice are played down. S The larger die is played on the far side, and the smaller die is played into the outer board from the opponent's outer board. When no such play exists, S can also be used as an alternative to Z. Three dice are played on the far side, and one die is played down. When no such play exists, S can also be used as an alternative to Z. Z The smaller die is played on the far side, and the larger die is played into the outer board from the opponent's outer board. One die is played on the far side, and three dice are played down.

S (Split) Family

Traditional Notation	Far 1	Down 1	Jump 0	Inside 0	Hits on These Points (more is better) (higher is better)	Owned Points Not Held by All Members in Family (more is better) (closer to 6pt is better)	Blot and Spare Destinations (closer to 6pt is better) (outer board: farther is better)	Nactation
24/20, 13/10	24/20	13/10					10pt 20pt	Z

The rules governing the $ (Slot) family have changed considerably since 2009. You “slot” by moving a checker down, and putting it (or another checker) onto a vacant offensive point. Two points are worth noting: When a slotting play uses only part of a roll, the remainder must be played “down” (unless it is used to enter from the bar). “Down” means a move made to or within the outer board. The checker must land in the outer board on the near side, but can be moved from any point in either outer board. Hitting loose is not the same thing as slotting. Slotting means placing a blot on an empty point. The only hits that occur in slotting plays are the incidental hits made in the outer board when playing down, or in the opponent's home board when a checker is entered from the bar. Ranking rules for slotting plays are a little different than the ranking rules in the Hit/Most/Six Rule. Here are the slotting rules: Slot 5pt or 4pt Most Points Unstack the taller point Order of preference for slotted point: 5pt, 4pt, then 7pt, 3pt, 2pt, 1pt In addition to these, Nack acknowleges in a post from November 2011 that, “the [6pt Convention] does apply as a tie-breaker in the outer board, but it arises so seldom that I didn't append it as a fifth rule.” In the Nactations that follow, we consider only those plays that slot the 4pt or the 5pt. Although there are other slotting plays in the family, they all slot 2pt or 3pt, and so rank lower than the ones presented here.

$ (Slot) and % (Alternate slot) Family

Traditional Notation	Slots 4pt or 5pt?	Owned Points Not Held by All Members in Family (more is better) (closer to 6pt is better)	Height of Point Being Unstacked	Slotted Points	Destinations of Other Blots and Spares (closer to 6pt is better) (outer board: farther is better)	Nactation
15/11, 8/5	yes		3	5pt	11pt*	$
13/9, 8/5	yes		3	5pt	9pt*	%
13/10, 8/4	yes		3	4pt*	10pt	$

^*This is the deciding criterion.

It is interesting to note that the unstated fifth rule of slotting had to be invoked in order to discriminate between the top two members of the $ (Slot) family.

Mike

Messages In This Thread

• Nactation after the initial moves
  Andreas -- Wednesday, 25 November 2009, at 7:08 p.m.
  • Nactation after the initial moves
    Stick -- Wednesday, 25 November 2009, at 8:18 p.m.
  • Nactation after the initial moves
    Timothy Chow -- Wednesday, 25 November 2009, at 10:00 p.m.
  • Nactation after the initial moves
    Matt Cohn-Geier -- Wednesday, 25 November 2009, at 10:47 p.m.
  • Nactation after the initial moves
    Stein Kulseth -- Thursday, 26 November 2009, at 10:39 a.m.
  • Nactation after the initial moves
    Nack Ballard -- Thursday, 26 November 2009, at 1:05 p.m.
  • Nactation after the initial moves
    Andreas -- Thursday, 26 November 2009, at 8:12 p.m.
  • Nactations of 63R-42P-43 — 2011 Update
    Taper_Mike -- Saturday, 17 December 2011, at 9:18 p.m.
    • Nactations of 63R-42P-43 — 2011 Update
      Nack Ballard -- Sunday, 18 December 2011, at 2:14 a.m.
      • Nactation Questions — Clarifying the L (Lift) Family
        Taper_Mike -- Sunday, 18 December 2011, at 7:20 a.m.
        • Nactation Questions — Clarifying the L (Lift) Family
          Nack Ballard -- Sunday, 18 December 2011, at 6:33 p.m.