Archive for the ‘Bearoff’ Category

What to do?

April 15, 2007

Here’s a situation that arose yesterday during the ongoing G. v D. money session at GCCRC.

Should “O” double? If so, should “X” take?

The score (after 0 games) is: P0 82, P1 107
Match Information:

Date: April 13, 2007
Move number 6: O on roll, cube decision?

 GNU Backgammon  Position ID: 3lkAANj5AQAAAA
                 Match ID   : AgEAACAFWAMA
 +12-11-10--9--8--7-------6--5--4--3--2--1-+     O: P0 (Cube: 4)
 |                  |   |       O     O  O | O   82 points
 |                  |   |       O     O  O | O   On roll
 |                  |   |       O     O    | O  
 |                  |   |       O          | O  
 |                  |   |       6          |   
^|                  |BAR|                  |    
 |                  |   |                  | X 
 |                  |   |             X    | X  
 |                  |   |          X  X    | X  
 |                  |   |    X     X  X    | X  
 |                  |   | X  X     X  X    | X   107 points
 +13-14-15-16-17-18------19-20-21-22-23-24-+     X: P1
Pip counts: O 32, X 33

I’ve done a rollout using gnuBG, but I’ll wait a couple of days before posting the result. In the meantime, post your opinion/reasoning using the Comment box below (sorry, no prizes for correct answers).

Cube analysis
Rollout cubeless equity  +0.142

Cubeful equities:
1. No double            +0.302
2. Double, pass         +1.000  ( +0.698)
3. Double, take         +0.007  ( -0.295)
Proper cube action: No redouble, take (29.7%)

Rollout details:
  Player P0 owns 4-cube:
    0.571 0.000 0.000 - 0.429 0.000 0.000 CL  +0.142 CF  +0.302
   [0.000 0.000 0.000 - 0.000 0.000 0.000 CL   0.000 CF   0.000]
  Player P1 owns 8-cube:
    0.571 0.000 0.000 - 0.429 0.000 0.000 CL  +0.284 CF  +0.007
   [0.000 0.000 0.000 - 0.000 0.000 0.000 CL   0.000 CF   0.000]
Full cubeful rollout with var.redn.
60656 games, Mersenne Twister dice gen. with seed 1057640406 and quasi-random dice
Play: supremo 2-ply cubeful prune [world class]
keep the first 0 0-ply moves and up to 16 more moves within equity 0.32
Skip pruning for 1-ply moves.
Cube: 2-ply cubeful prune [world class]

Advertisements