I See Said the Blind Man


Despite my best intentions of posting regularly and working through 501 Essential Problems along with Boot Camp my blog is going largely unattended. I am playing a lot of online tourneys, but not spending the in study and analysis I should be. And writing things for a blog as opposed to notes for myself takes more time. But I wanted to post a position that I was just looking at from the analysis of one of my matches. Maybe it is overly simple, but it took be quite a while to see what would have lead me to the right answer so maybe someone else will find it of interest.

My thought process when I played 20/17 with the three was to reduce the chances of getting hit.  Playing 20/17 as opposed to the correct play of 8/5 with the 3 leaves 9 shots as opposed to 11 shots.

When I first looked at this error in the analysis I was left scratching my head about what I would have seen during the match that would have lead me to the correct the play. My play actually gives a fractionally high winning percentage, but is a blunder based on equity due to the extra gammons (and backgammons) picked up with the correct play. 

I was about to give up on ever being able to see this in the course of a match, when suddenly the answer hit my, and it is remarkable simple. While leaving the blot on the 5 gives black 2 more shots at hitting it, it also gives white potentially 3 more shots at picking up the blot next turn if black is unable to move it.  The moral of the story for me is to not only think defensively, but think about how to give yourself the best chance of picking up the blot. 

is Player 2

score: 1
pip: 100

11 point match
pip: 119
score: 0

is Player 1

to play 53

1. Rollout1 Bar/20* 8/5 eq: +1.051
80.01% (G:26.77% B:2.06%)
19.99% (G:4.55% B:0.06%)
Conf: ± 0.012 (+1.039…+1.063)
Duration: 8 minutes 32 seconds
2. Rollout1 Bar/20* 20/17 eq: +0.925 (-0.126)
80.52% (G:25.51% B:1.77%)
19.48% (G:7.29% B:0.12%)
Conf: ± 0.011 (+0.914…+0.936)
Duration: 11 minutes 25 seconds
1 1296 Games rolled with Variance Reduction.
Dice Seed: 25
Moves and cube decisions: 3 ply

eXtreme Gammon Version: 1.11, MET: eXtremeGammon


One thought on “I See Said the Blind Man

  1. Nice problem and analysis. It is also worth noting that even though bar/20* 8/5 leaves more shots, most of them involve Black hitting you loose on the 5-point, leaving you with 11 return shots. If Black hits you after you play bar/20* 20/17, then you have don’t have many return shots, and if you dance then Black has a direct shot at picking up your second blot. Thus you get gammoned more often with bar/20* 20/17.

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