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Blitz cube with 2pt board - Rollout

Posted By: mtuhtan
Date: Tuesday, 19 April 2011, at 5:40 p.m.

In Response To: Blitz cube with 2pt board (51S+11S-54R+65H-F+C?) (mtuhtan)

As Neil noticed, these aren't blitz cubes, but I chose this title because I think it reflects my opponent's thinking process (in second position).

As most people here probably know, most cubes in first few rolls when defender is on bar and attacker has only two point board are no doubles or just small doubles (32S-22N-F-C, 53P-41S-62H-F-C, 53P-64S-51D-F-C, 53P-21S-64H-F-C, etc.)

But here, attacker has escaped with one back checker and has much better (around 5% more) winning chances. That translates to relatively big double, as we can see:





White is Player 2

score: 0
pip: 163
Money session
pip: 152
score: 0

Blue is Player 1
XGID=aa---BC-C--AdE---d-e----A-:0:0:1:00:0:0:0:0:10
Blue on roll, cube action?


Analyzed in Rollout
No Double
Player Winning Chances: 70,43% (G: 19,81% B: 0,89%)
Opponent Winning Chances: 29,57% (G: 5,46% B: 0,21%)
Double/Take
Player Winning Chances: 70,60% (G: 20,24% B: 0,89%)
Opponent Winning Chances: 29,40% (G: 5,38% B: 0,21%)
Cubeless Equities
No Double:+0,559
Double:+1,135
Cubeful Equities
No Double:+0,860 (-0,056)
Double/Take:+0,915
Double/Drop:+1,000 (+0,085)
Best Cube action: Double / Take
Rollout details
5184 Games rolled with Variance Reduction.
Dice Seed: 45297676
Moves and cube decisions: 3 ply
Confidence No Double: ± 0,010 (+0,850...+0,869)
Confidence Double: ± 0,012 (+0,903...+0,927)
Double Decision confidence: 100,0%
Take Decision confidence: 100,0%
Duration: 50 minutes 34 seconds

eXtreme Gammon Version: 1.21


I failed to double and one roll later we have this position. I have two more attackers on 8pt and 11pt.

Now it's easy to find correct cube decision when we know rollout result of first position. But probably it is surprising how big pass this is.

I doubled and my opponent took it, probably knowing that in early game two point board means big take, so this must be take too, maybe just a little smaller (closer to pass).

If he was practicing versus bot, this decision would never show up* as bot would double him on first opportunity (on previous roll).
That's why I think take/pass decisions versus human opponent are harder than versus bot (as mentioned in "Why do I suck" thread).


* Ok, I wouldn't bet on that as I'm sure Nack could find a sequence where on previous roll it was no double





White is Player 2

score: 0
pip: 163
Money session
pip: 145
score: 0

Blue is Player 1
XGID=aa---BC-D--BdC---d-e----A-:0:0:1:00:0:0:0:0:10
Blue on roll, cube action?


Analyzed in Rollout
No Double
Player Winning Chances: 73,19% (G: 22,21% B: 0,94%)
Opponent Winning Chances: 26,81% (G: 4,72% B: 0,17%)
Double/Take
Player Winning Chances: 73,94% (G: 21,54% B: 1,00%)
Opponent Winning Chances: 26,06% (G: 4,42% B: 0,19%)
Cubeless Equities
No Double:+0,646
Double:+1,316
Cubeful Equities
No Double:+0,946 (-0,054)
Double/Take:+1,123 (+0,123)
Double/Drop:+1,000
Best Cube action: Double / Drop
Rollout details
2592 Games rolled with Variance Reduction.
Dice Seed: 45297676
Moves and cube decisions: 3 ply
Confidence No Double: ± 0,010 (+0,935...+0,956)
Confidence Double: ± 0,019 (+1,104...+1,142)
Double Decision confidence: 100,0%
Take Decision confidence: 100,0%
Duration: 20 minutes 38 seconds

eXtreme Gammon Version: 1.21

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