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## RE: [Bug-gnubg] Re: Checkerplay vs cube decision errors

 From: Albert Silver Subject: RE: [Bug-gnubg] Re: Checkerplay vs cube decision errors Date: Sun, 23 May 2004 12:06:37 -0300

```> The small  effect of cube errors  on overall performance  allso gives
an
> interesting  perspective on  the so-called  "pip-counting"  methods.
It
> follows that for almost everyone,  learning to accurately pip-count is
a
> complete waste of time.

That's a very mistaken assumption IMO. You're assuming that the
pip-count is only of use, or mostly of use, for cube decisions, and
while it is certainly an unquestionable factor, it also *strongly*
affects many checker play decisions.

For example, anchor breaking decisions are often strongly influenced by
the race, if not decided by it. Look at the position I constructed
below. Xs have just rolled a wonderful 6-3, and can choose which point
to break. Which will it be, the 17 or the 14? Well, I will look closely
at the pip-count. If I'm behind in the race, I will definitely break the
14 point:

GNU Backgammon  Position ID: bBvwAQDbPcAYAA
Match ID   : cAkPAAAAAAAA
+13-14-15-16-17-18------19-20-21-22-23-24-+     O: Os
|    X        X    |   | O  O  O  O       | O   0 points
|    X        X    |   | O  O  O  O       | O
|                  |   |                  |
|                  |   |                  |
|                  |   |                  |
v|                  |BAR|                  |     (Cube: 1)
| O                |   |                  |
| O                |   | X                |     ñL
| O                |   | X  X             |
| O                |   | X  X  X  X       |     Rolled 63
| O                |   | X  X  X  X       |     0 points
+12-11-10--9--8--7-------6--5--4--3--2--1-+     X: Xs

Xs: 115 pips (+14)      Os: 101 pips (-14)

1. Cubeful 2-ply    14/11 14/8        Eq.:  -0.303
40.0%   0.0%   0.0% -  60.0%   1.2%   0.0%
2-ply cubeful 100% speed [world class]
2. Cubeful 2-ply    14/8 5/2          Eq.:  -0.387 (-0.084)
39.2%   0.0%   0.0% -  60.8%   5.2%   0.2%
2-ply cubeful 100% speed [world class]
3. Cubeful 2-ply    14/8 6/3          Eq.:  -0.395 (-0.092)
38.9%   0.0%   0.0% -  61.1%   5.2%   0.2%
2-ply cubeful 100% speed [world class]
4. Cubeful 2-ply    14/5              Eq.:  -0.434 (-0.131)
37.7%   0.0%   0.0% -  62.3%   4.9%   0.1%
2-ply cubeful 100% speed [world class]
5. Cubeful 2-ply    17/14 17/11       Eq.:  -0.454 (-0.151)
35.0%   0.0%   0.0% -  65.0%   0.6%   0.0%
2-ply cubeful 100% speed [world class]

On the other hand, if I'm not, then I'll prefer the 17 point.

GNU Backgammon  Position ID: bBvwAQDbDjAGAA
Match ID   : cAkPAAAAAAAA
|    X        X    |   | O  O  O  O       | O   0 points
|    X        X    |   | O  O  O  O       | O
|                  |   |                  |
|                  |   |                  |
|                  |   |                  |
v|                  |BAR|                  |     (Cube: 1)
| O                |   |                  |
| O                |   |                  |     ñL
| O                |   | X                |
| O                |   | X  X  X  X       | X   Rolled 63
| O                |   | X  X  X  X       | X   0 points
+12-11-10--9--8--7-------6--5--4--3--2--1-+     X: SubtleOne

Xs: 104 pips (+3)       Os: 101 pips (-3)

1. Cubeful 2-ply    17/14 17/11         Eq.:  +0.062
52.3%   0.0%   0.0% -  47.7%   0.0%   0.0%
2-ply cubeful 100% speed [world class]
2. Cubeful 2-ply    14/11 14/8          Eq.:  +0.020 (-0.042)
50.8%   0.0%   0.0% -  49.2%   0.0%   0.0%
2-ply cubeful 100% speed [world class]
3. Cubeful 2-ply    14/5                Eq.:  -0.137 (-0.199)
45.4%   0.0%   0.0% -  54.6%   0.0%   0.0%
2-ply cubeful 100% speed [world class]

In fact, the more I'm ahead, the more breaking the 17 is to be
preferred.

GNU Backgammon  Position ID: bBvwAQDbBhgDAA
Match ID   : cAkPAAAAAAAA
|    X        X    |   | O  O  O  O       | O   0 points
|    X        X    |   | O  O  O  O       | O
|                  |   |                  |
|                  |   |                  |
|                  |   |                  |
v|                  |BAR|                  |     (Cube: 1)
| O                |   |                  |
| O                |   |                  |     ñL
| O                |   |                  | X
| O                |   | X  X  X  X       | X   Rolled 63
| O                |   | X  X  X  X       | X   0 points
+12-11-10--9--8--7-------6--5--4--3--2--1-+     X: SubtleOne

Xs: 98 pips (-3)                Os: 101 pips (+3)

1. Cubeful 2-ply    17/14 17/11         Eq.:  +0.174
56.5%   0.0%   0.0% -  43.5%   0.0%   0.0%
2-ply cubeful 100% speed [world class]
2. Cubeful 2-ply    14/11 14/8          Eq.:  +0.102 (-0.072)
53.9%   0.0%   0.0% -  46.1%   0.0%   0.0%
2-ply cubeful 100% speed [world class]
3. Cubeful 2-ply    14/5                Eq.:  -0.104 (-0.278)
46.6%   0.0%   0.0% -  53.4%   0.0%   0.0%
2-ply cubeful 100% speed [world class]

Of course there are numerous other circumstances that can be shown, and
this is but a minor one, but it should help illustrate the importance of
the race in checker play decisions.

Albert

```