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*RO* of "Endgame 53" and variants.

Posted By: Dmitriy Obukhov
Date: Thursday, 26 May 2011, at 10:13 p.m.

In Response To: Endgame 53 (Dmitriy Obukhov)

As rollout shows simple 6/1 3/0 is best.




White is Player 2

score: 6
pip: 49
7 point match
Crawford
pip: 40
score: 2

Blue is Player 1
XGID=-DCDC-A-------a-----baecc-:0:0:1:53:2:6:1:7:10
Blue to play 53

1.Rollout16/1 3/Offeq: +0.6660
Player:
Opponent:
83.30% (G:0.00% B:0.00%)
16.70% (G:0.00% B:0.00%)
Conf.: ±0.0000 (+0.6660...+0.6660) - [100.0%]
Duration: 0.4 second
2.Rollout16/3 4/Offeq: +0.6427 (-0.0233)
Player:
Opponent:
82.13% (G:0.00% B:0.00%)
17.87% (G:0.00% B:0.00%)
Conf.: ±0.0000 (+0.6427...+0.6427) - [0.0%]
Duration: 0.4 second
3.XG Roller+6/1 4/1eq: +0.3110 (-0.3550)
Player:
Opponent:
65.55% (G:0.00% B:0.00%)
34.45% (G:0.00% B:0.00%)
1 10368 Games rolled with Variance Reduction.
Moves and cube decisions: 3-ply

eXtreme Gammon Version: 2.00.163.beta, MET: Kazaross XG2

But what is the reason Blue should not play for double 3's? First, let me throw out a theory that if the race was closer Blue would have more reasons to play for 33.




White is Player 2

score: 6
pip: 42
7 point match
Crawford
pip: 40
score: 2

Blue is Player 1
XGID=-DCDC-A-------------bbecc-:0:0:1:53:2:6:1:7:10
Blue to play 53

1.Rollout16/1 3/Offeq: +0.2901
Player:
Opponent:
64.51% (G:0.00% B:0.00%)
35.49% (G:0.00% B:0.00%)
Conf.: ±0.0000 (+0.2901...+0.2902) - [100.0%]
Duration: 7.8 seconds
2.Rollout16/3 4/Offeq: +0.2656 (-0.0245)
Player:
Opponent:
63.28% (G:0.00% B:0.00%)
36.72% (G:0.00% B:0.00%)
Conf.: ±0.0000 (+0.2656...+0.2657) - [0.0%]
Duration: 7.2 seconds
3.3-ply6/1 4/1eq: -0.1863 (-0.4764)
Player:
Opponent:
40.68% (G:0.00% B:0.00%)
59.32% (G:0.00% B:0.00%)
1 10368 Games rolled with Variance Reduction.
Moves and cube decisions: 3-ply

eXtreme Gammon Version: 2.00.163.beta, MET: Kazaross XG2

Making the race closer actually made the "fancy" play worse. What happens if the roll is changed to 54 so the 'fancy' play benefits from 22 later?




White is Player 2

score: 6
pip: 49
7 point match
Crawford
pip: 40
score: 2

Blue is Player 1
XGID=-DCDC-A-------a-----baecc-:0:0:1:54:2:6:1:7:10
Blue to play 54

1.Rollout16/1 4/Offeq: +0.6802
Player:
Opponent:
84.01% (G:0.00% B:0.00%)
15.99% (G:0.00% B:0.00%)
Conf.: ±0.0000 (+0.6802...+0.6802) - [100.0%]
Duration: 0.3 second
2.Rollout16/2 4/Offeq: +0.6755 (-0.0047)
Player:
Opponent:
83.77% (G:0.00% B:0.00%)
16.23% (G:0.00% B:0.00%)
Conf.: ±0.0000 (+0.6755...+0.6755) - [0.0%]
Duration: 0.4 second
1 10368 Games rolled with Variance Reduction.
Moves and cube decisions: 3-ply

eXtreme Gammon Version: 2.00.163.beta, MET: Kazaross XG2

That changed things quite a bit. Still, Blue may miss with any two's even after 22. Removing one checker, and therefore reducing a chance of a miss after 22 makes the 'fancy' play right:




White is Player 2

score: 6
pip: 49
7 point match
Crawford
pip: 36
score: 2

Blue is Player 1
XGID=-DCDB-A-------a-----baecc-:0:0:1:54:2:6:1:7:10
Blue to play 54

1.Rollout16/2 4/Offeq: +0.7412
Player:
Opponent:
87.06% (G:0.00% B:0.00%)
12.94% (G:0.00% B:0.00%)
Conf.: ±0.0000 (+0.7412...+0.7412) - [100.0%]
Duration: 0.3 second
2.Rollout16/1 4/Offeq: +0.7407 (-0.0005)
Player:
Opponent:
87.04% (G:0.00% B:0.00%)
12.96% (G:0.00% B:0.00%)
Conf.: ±0.0000 (+0.7407...+0.7407) - [0.0%]
Duration: 0.3 second
1 10368 Games rolled with Variance Reduction.
Moves and cube decisions: 3-ply

eXtreme Gammon Version: 2.00.163.beta, MET: Kazaross XG2

One more rollout:




White is Player 2

score: 6
pip: 49
7 point match
Crawford
pip: 40
score: 2

Blue is Player 1
XGID=-DCDC-A-------a-----baecc-:0:0:1:52:2:6:1:7:10
Blue to play 52

1.Rollout16/Offeq: +0.6350
Player:
Opponent:
81.75% (G:0.00% B:0.00%)
18.25% (G:0.00% B:0.00%)
Conf.: ±0.0000 (+0.6350...+0.6350) - [100.0%]
Duration: 0.2 second
2.Rollout16/1 2/Offeq: +0.6120 (-0.0230)
Player:
Opponent:
80.60% (G:0.00% B:0.00%)
19.40% (G:0.00% B:0.00%)
Conf.: ±0.0000 (+0.6120...+0.6120) - [0.0%]
Duration: 0.2 second
3.XG Roller+6/1 4/2eq: +0.3172 (-0.3178)
Player:
Opponent:
65.86% (G:0.00% B:0.00%)
34.14% (G:0.00% B:0.00%)
4.2-ply6/1 3/1eq: +0.3018 (-0.3332)
Player:
Opponent:
65.09% (G:0.00% B:0.00%)
34.91% (G:0.00% B:0.00%)
1 10368 Games rolled with Variance Reduction.
Moves and cube decisions: 3-ply

eXtreme Gammon Version: 2.00.163.beta, MET: Kazaross XG2

Now fancy play gains more due to reinforced 2pt. So what is the reason fancy play is wrong in the original position? To be honest I am not sure. But it seems to me it is a combination of a few factors: extra pip, 33 doesnt always save a roll, possible misses with one's and two's, etc. Neither one is enough to make fancy play correct [e.g. probability of throwing 33 is greater than probability of throwing a bunch of single aces], but all those little things combine beat the benefit of double 3's, which dont even always save a roll. What happens if the checker from the 3pt is moved to 2pt?




White is Player 2

score: 6
pip: 49
7 point match
Crawford
pip: 39
score: 2

Blue is Player 1
XGID=-DDCC-A-------a-----baecc-:0:0:1:53:2:6:1:7:10
Blue to play 53

1.Rollout16/3 4/Offeq: +0.6755
Player:
Opponent:
83.77% (G:0.00% B:0.00%)
16.23% (G:0.00% B:0.00%)
Conf.: ±0.0000 (+0.6755...+0.6755) - [100.0%]
Duration: 0.0 second
2.Rollout16/1 3/Offeq: +0.6743 (-0.0012)
Player:
Opponent:
83.72% (G:0.00% B:0.00%)
16.28% (G:0.00% B:0.00%)
Conf.: ±0.0000 (+0.6743...+0.6743) - [0.0%]
Duration: 0.3 second
3.XG Roller+6/1 4/1eq: +0.3274 (-0.3481)
Player:
Opponent:
66.37% (G:0.00% B:0.00%)
33.63% (G:0.00% B:0.00%)
1 10368 Games rolled with Variance Reduction.
Moves and cube decisions: 3-ply

eXtreme Gammon Version: 2.00.163.beta, MET: Kazaross XG2

now, after the fancy play 33 takes 4 checkers off instead of 2 and deuce point is reinforced as well.

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