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Old 05-19-2018, 04:30 PM   #1
deh
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Join Date: Mar 2011
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6-1, end game



White - Pips 35 (-8)

Black - Pips 43 (+8)
Black to Play 6-1
Created with Diagram Builder


Any way to 'calculate' the right play here?

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Old 05-23-2018, 09:53 PM   #2
jjpregler
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Re: 6-1, end game

You trail by 3 crossovers. Bill Robertie wrote in articles previously, that trailing by 3 crossovers is the break even point to take 2 off here.

When you trail by 2 crossovers or less, play safe. When you trail by 4 or more crossovers, play aggressively and take 2 off.

When you trail by exactly 3, both plays have roughly the same equity. And while it is not always the "correct" answer in XG, I usually decide based on number of checkers off. Does taking an extra checker save me a full roll? Here no, so I would probably take 1 off, but I won't be surprised if XG says that taking 2 off is slightly ahead.
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Old 05-23-2018, 10:33 PM   #3
deh
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Re: 6-1, end game

Quote:
Originally Posted by jjpregler View Post
You trail by 3 crossovers. Bill Robertie wrote in articles previously, that trailing by 3 crossovers is the break even point to take 2 off here.

When you trail by 2 crossovers or less, play safe. When you trail by 4 or more crossovers, play aggressively and take 2 off.

When you trail by exactly 3, both plays have roughly the same equity. And while it is not always the "correct" answer in XG, I usually decide based on number of checkers off. Does taking an extra checker save me a full roll? Here no, so I would probably take 1 off, but I won't be surprised if XG says that taking 2 off is slightly ahead.
Good rule!
taking 2 off is .100 error here.
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Old 05-24-2018, 09:29 AM   #4
Robertie
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Re: 6-1, end game

I'm not sure how you got your answer, but I just did a rollout on XG and got 6/off 1/off as better than 6/off 6/1 by .023. That's close, as my little formula would suggest. but two men off is clearly better.
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Old 05-24-2018, 11:19 AM   #5
jjpregler
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Re: 6-1, end game

Quote:
Originally Posted by Robertie View Post
I'm not sure how you got your answer, but I just did a rollout on XG and got 6/off 1/off as better than 6/off 6/1 by .023. That's close, as my little formula would suggest. but two men off is clearly better.
How do decide on the 3 behind break even point OTB with your rule?
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Old 05-24-2018, 02:02 PM   #6
Robertie
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Re: 6-1, end game

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Originally Posted by jjpregler View Post
How do decide on the 3 behind break even point OTB with your rule?
Could you rephrase the question? Three behind is the break-even point.
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Old 05-24-2018, 02:23 PM   #7
jjpregler
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Re: 6-1, end game

When you are 3 cross overs behind, you are at the break even point between playing safe and playing bold and taking 2 off.

When you are playing over the board, and you come across a position such as this, when you are at the 3 behind break even point, what factors do you consider when choosing to either play safe or take 2 off? The number of checkers off? The point being opened? and etc.
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Old 05-24-2018, 02:38 PM   #8
Robertie
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Re: 6-1, end game

Since you're at the break-even point, you can't make a serious mistake no matter what you do. I'd probably just default to taking two off. That's surely the play that will impress spectators the most!
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Old 05-24-2018, 04:42 PM   #9
deh
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Re: 6-1, end game

Quote:
Originally Posted by Robertie View Post
I'm not sure how you got your answer, but I just did a rollout on XG and got 6/off 1/off as better than 6/off 6/1 by .023. That's close, as my little formula would suggest. but two men off is clearly better.
Sorry, that was me working on a variant of the position.

The one above is:

XGID=aCBBBBB----------------e--:1:1:1:61:0:0:3:0:10



1. Rollout¹ 6/Off 1/Off eq:+0.128
Player: 46.89% (G:0.00% B:0.00%)
Opponent: 53.11% (G:0.00% B:0.00%)
Confidence: ±0.004 (+0.124..+0.132) - [100.0%]
Duration: 4.0 seconds

2. Rollout¹ 6/5 6/Off eq:+0.104 (-0.023)
Player: 47.25% (G:0.00% B:0.00%)
Opponent: 52.75% (G:0.00% B:0.00%)
Confidence: ±0.004 (+0.100..+0.109) - [0.0%]
Duration: 3.1 seconds
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