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Backgammon => Fibsboard Forum Matches => FFM 19 => Topic started by: Julia_H on August 22, 2014, 08:09:19 PM

Poll
Question: Cube action?
Option 1: Take
Option 2: Drop
Title: FFM19 Game 3 Move 33: Herd cube action?
Post by: Julia_H on August 22, 2014, 08:09:19 PM
So, play for the match?
Title: Re: FFM19 Game 3 Move 33: Herd cube action?
Post by: ah_clem on August 22, 2014, 08:31:06 PM
Spoiler

If we take, we're playing for the match and our match wining chance is equal to our game winning chance.

If we pass we're at 3a 2a and the match equity tables say that's about 40% to win the match.

So, are we 40% to win here?  He hits us 23/36 times or about 64%.  But not all of those are losses.  He misses 13/36 or about 36% of the time, but not all of those are wins for us - we still need one of the ~16 shakes to get by him and the hitting numbers give him counterplay due to our crunched board.

My wild estimate is that we win about 25% of the times he hits, and maybe  60% of the times when we're missed.

That gives .64(.25) +  .36(.6) = .16 + .216 = .376 which is less than the .4 we need to take.

Had we rolled something other than the lousy 33 and still had some semblance of a board I think we could take.  I'm going to pass this one.

pass.
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Title: Re: FFM19 Game 3 Move 33: Herd cube action?
Post by: dorbel on August 22, 2014, 09:05:46 PM
Can't comment on this one as I already know the answer from XG.
Title: Re: FFM19 Game 3 Move 33: Herd cube action?
Post by: KDP on August 22, 2014, 10:36:14 PM
Spoiler
just because we might get hit, doesn't mean we will get hit, and even if we are hit with our racing lead and the open 6 we still have great chances to win the game. i would even go as far as to say that i'm not even sure the re-double is correct but thats not my problem. take. 
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Title: Re: FFM19 Game 3 Move 33: Herd cube action?
Post by: jeff on August 22, 2014, 11:10:17 PM
Spoiler
Pass. Believe you (clem) are overestimating our chances.

I count only 10 rolls that pass him: 63, 54, 64, 65, 55, 44, are clear winners (10/36 = 28%).  Also, 62, 53 give him 11/36 returns (4/36 * 25/36 = we win 7%). That is, we win about 35% when he misses.

I'll give you the 25% win when he hits (although it seems to me we can only with with a 66 on one of the next two or three rolls, let's say 6% or 8% of winning, or a late hit, which beyond my ability to estimate, but gotta be small).

But that in your equation and it's an even clearer drop.

How does one estimate chances of a late hit?
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Title: Re: FFM19 Game 3 Move 33: Herd cube action?
Post by: Julia_H on August 23, 2014, 08:20:17 PM
I really don't want this big decision to go to a tie-breaker - I'll leave voting open up to 11pm (London time) tonight to see if one more person wants to add their opinion. I also have seen what GNU makes of it and don't want to bias things...
Title: Extreme Gammon Rollout
Post by: willywonka on August 24, 2014, 01:43:15 AM
Spoiler

Analyzed in Rollout
No redouble
 Player Winning Chances:   54.27% (G:2.46% B:0.06%)
 Opponent Winning Chances: 45.73% (G:2.97% B:0.01%)
Redouble/Take
 Player Winning Chances:   55.18% (G:2.20% B:0.04%)
 Opponent Winning Chances: 44.82% (G:4.66% B:0.02%)

Cubeless Equities: No Double=+0.106, Double=+0.770

Cubeful Equities:
      No redouble:     +0.537 (-0.233)
      Redouble/Take:   +0.770
      Redouble/Pass:   +1.000 (+0.230)

Best Cube action: Redouble / Take

Rollout:
 5184 Games rolled with Variance Reduction.
 Dice Seed: 57300016
 Moves and cube decisions: XG Roller+
 Confidence No Double: ± 0.002 (+0.535..+0.539)
 Confidence Double:    ± 0.003 (+0.766..+0.773)

 Double Decision confidence: 100.0%
 Take Decision confidence: 100.0%

 Duration: 40 minutes 14 seconds

eXtreme Gammon Version: 2.10, MET: Kazaross XG2
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Title: Re: FFM19 Game 3 Move 33: Herd cube action?
Post by: ah_clem on August 24, 2014, 02:00:07 AM
XG rollout

Spoiler

Our takepoint was 40%.  It appears we were more than that. Tomorrow, I'll take a look at our chances after being missed and after being hit.  Interesting cube actions.


XGID=-DCFA----a-ab-----A-bbbcb-:1:-1:-1:00:2:1:0:5:10

X:Player 1   O:Player 2
Score is X:2 O:1 5 pt.(s) match.
+12-11-10--9--8--7-------6--5--4--3--2--1-+
|                X |   |    O  O  O  O  O | +---+
|                  |   |    O  O  O  O  O | | 2 |
|                  |   |             O    | +---+
|                  |   |                  |
|                  |   |                  |
|                  |BAR|                  |
|                  |   |          6       |
|                  |   |          X     X |
|                  |   |          X  X  X |
| O                |   |          X  X  X |
| O  O     O       |   |       X  X  X  X |
+13-14-15-16-17-18------19-20-21-22-23-24-+
Pip count  X: 50  O: 88 X-O: 2-1/5
Cube: 2, O own cube
O on roll, cube action

Analyzed in Rollout
No redouble
  Player Winning Chances:   54.35% (G:2.46% B:0.06%)
  Opponent Winning Chances: 45.65% (G:3.49% B:0.03%)
Redouble/Take
  Player Winning Chances:   55.03% (G:2.00% B:0.03%)
  Opponent Winning Chances: 44.97% (G:4.26% B:0.01%)

Cubeless Equities: No Double=+0.103, Double=+0.763

Cubeful Equities:
       No redouble:     +0.538 (-0.225)
       Redouble/Take:   +0.763
       Redouble/Pass:   +1.000 (+0.237)

Best Cube action: Redouble / Take

Rollout:
  1296 Games rolled with Variance Reduction.
  Moves: 3-ply, cube decisions: XG Roller
  Confidence No Double: ± 0.005 (+0.532..+0.543)
  Confidence Double:    ± 0.008 (+0.755..+0.770)

  Double Decision confidence: 100.0%
  Take Decision confidence: 100.0%

  Duration: 22.6 seconds

eXtreme Gammon Version: 2.10, MET: Kazaross XG2


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