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Backgammon + The Goldilocks Zone - Define - Rollout - Long

Posted By: Stick
Date: Saturday, 3 May 2014, at 9:57 p.m.

In Response To: Backgammon + The Goldilocks Zone - Define (Stick)

So often with backgammon items I wonder 'Who discovered that first?'. For example, with 'next' used in the context of a problem being so easy almost everyone would get it correct and it's hardly worth discussing usually in reference to an OLM. I know this existed before I existed in the backgammon world being used on Kit's forums. I think I did popularize it and obnoxify it by overusing it and adding the exclamation point, Next!

The term 'donkey' is borrowed from poker of course and would have matriculated into the bg world one way or another having so many crossover players. These forums and my own usage certainly jettisoned it into the mainstream.

I brought this thread up because I quote a lot of things in lessons because I sometimes say "I thought of this when ..." and I am hoping I'm not taking credit for what someone else deserves credit for. (things more important than donkeys and nexts)

For example, I use the Goldilocks Zone to describe the ballpark amount of pips that is the perfect amount to be ahead in your standard high anchor holding game. This is around 25-35 pips. The two problems I show:





White is Player 2

score: 0
pip: 139
Unlimited Game
Jacoby Beaver
pip: 109
score: 0

Blue is Player 1
XGID=---BBbD-D---cC---bbbbb----:0:0:1:00:0:0:3:0:10
Blue on roll, cube action?

Analyzed in Rollout No double Double/Take
Player Winning Chances: 76.95% (G:3.26% B:0.05%) 77.12% (G:3.01% B:0.05%)
Opponent Winning Chances: 23.05% (G:1.72% B:0.04%) 22.88% (G:1.75% B:0.04%)
Cubeless Equities +0.554 +1.110
Cubeful Equities
No double:+0.930 (-0.070)0.009 (+0.921..+0.938)
Double/Take:+1.000 (+0.000)0.009 (+0.991..+1.009)
Double/Pass:+1.000
Best Cube action: Double / Pass
Rollout details
1296 Games rolled with Variance Reduction.
Dice Seed: 13786468
Moves: 3-ply, cube decisions: XG Roller
Double Decision confidence:100.0%
Take Decision confidence:52.3%
Duration: 21 minutes 44 seconds

eXtreme Gammon Version: 2.10

After I show them the above first problem we then proceed to what if the doubler was ahead 10 more pips? More often than you may think in the position below people think that's better for the person doubling. Larger pip lead is better right? No, it's not. You compromise your flexibility and amount of time you have to roll the numbers needed to clear the midpoint while gaining almost nothing vis--vis the race. You already had a fairly gin race. More of a racing lead isn't going to be worth much.





White is Player 2

score: 0
pip: 139
Unlimited Game
Jacoby Beaver
pip: 99
score: 0

Blue is Player 1
XGID=--BBBbC-C---cC---bbbbb----:0:0:1:00:0:0:3:0:10
Blue on roll, cube action?

eXtreme Gammon Version: 2.10

Since nobody seemed to have heard this before I won't question taking credit for it. I think I was the first to use it but then again, I thought I attended 3 tournaments in one year and was later shown I attended 7 so I can't always trust my memory. Here are some other things I wonder about all relating to myself. Other people can worry about what they get credit for.

My amendments to the Keith Count to make it a little better. Normally with the Keith Count you can double if your count exceeds the opponent's by no more than 4. I found with longer racing you can double with a bigger difference. A race from 80-100 pips you can double exceeding the opponent's count by 5, from 100-120 by 6, and 120 or more by 7.

When memorizing the match equity numbers I always tried to piece together the equities by common sense or some pattern that made sense to me. The only one that I found of slight use for more than just like 3a 2a which I originally remembered because a ratio of 3 to 2 is 60/40 were the 7 away scores. If I remembered that 7a 1a Crawford was 9% I could then add 7% to that to get the match equity for all the other scores up to 7a 7a.

  • 7a 1a = 9% (Crawford)
  • 7a 2a = 16%
  • 7a 3a = 23%
  • 7a 4a = 30%
  • 7a 5a = 37%
  • 7a 6a = 44%
  • 7a 7a = 50% (Obviously)

What about my (non) doubling rule for the score of 3a 7a or greater? Can also be loosely applied to 3a 6a. Is it really something I tripped over or was it just something I discovered at a common score like countless other people but the first to put it in print. I'm assuming if it had ever been in print I would have come across it.

I assume others realized the importance of finding the dmp play before myself and I probably did to it what I did for 'Next!' but I can never remember seeing/hearing about that before applying it and over emphasizing it myself.

Stumbling into the fact that a ton of fourth roll positions have a 65/35 win percentage breakdown assuming [66] was the second roll and the other player rolled nothing special on his turns I'm sure was unique and has paid off for me on multiple occasions.

Those are all the specific things that come to mind now but I'm sure I'm forgetting some things. Others that would be interesting though impossible to track down would be other bg axioms like when in doubt, make the 5pt, once you've put a checker on the ace the best thing to do is cover it as soon as possible, if you have four or more checkers on the 6pt and already have the 5pt made and you roll [11] the best play is typically making the 4pt, etc... These axioms are well worth investigating to see if they hold true and when they don't noting the exceptions.

Stick

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