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10-21-2012 , 08:27 AM


What's our play here and why?
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10-21-2012 , 03:27 PM
I have a hard time with these spots. I'd probably double.
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10-21-2012 , 07:05 PM
Looks like Redouble / Pass to me.

My thinking. No way opponent can take and not too many gammons so let's not mess around just cash this game.

I cheated and put the position into the computer and apparently the position is Too Good.

My revised thinking. Backgammon is all about risk and reward and while there aren't too many gammons you just aren't risking too much so you might as well go for it. For example, I was playing around with the position - suppose you bring one man to safety and the the second man gets hit. This is a pretty bad scenario, yet even here you are about 60% to win.

Looks like the key is opponent's weak home board. While 4 points is decent, you are more than 50% to come in so it isn't that scary. As mentioned before, if you do get hit, then you have to scramble one man around while he has to scramble 2 or 3. Owning the cube, you are still favorite here.

By the way, I moved opponent's crunched spares to close the 5 point. Then he has a 5 point board, and not the computer says redouble / pass.

So my best guess is the strength of opponent's home board. 4 point board and you are not risking too much by going for the g-ball. On the other hand, getting hit with a 5 point board is a real disaster.
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10-21-2012 , 08:02 PM
I'm not sure I understand the "too good" part. For that to happen, you normally need some substantial gammon chances. Here, our gammon chances look pretty slim.
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10-21-2012 , 11:05 PM
If you could double after your roll instead, is there anything you could play (correctly) where he'd take? If the loose hits are takes, they have to be tiny since he's in such crappy shape when he misses. And there's plenty of stuff (any safe hit for sure) he'd love to snap-drop to get off the gammons.
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10-22-2012 , 09:18 AM
A tough problem. Over the board I would have doubled. (And expected a quick pass.)

Rollouts on Snowie and XG show the position is too good, but the cubeless numbers for gammons and losses show that Blue wins 15% gammons while losing 10% games, not the 2-to-1 gammon to loss ratio you're looking for when making a decision to play on. Obviously the accessible cube is saving a few losses along the way, making the position marginally too good. Very hard to get this right over the board because of the very low gammon numbers.

Last edited by Robertie; 10-22-2012 at 09:19 AM. Reason: typo
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10-22-2012 , 12:49 PM
Thanks for the analysis Bill. I tought the gammon % was more in the 8-10% range.
I didn't expect a number as high as 15%, even if it's not that high by itself.
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10-22-2012 , 11:46 PM
When you wait and then want to double him out next turn (basically anything where you don't hit except 55/66 and he's entered on 6), your 10% "losing chances" don't exist, but ALSO those are spots where your gammon chances are microscopic, so it's a pure gain. After one sequence, the game has almost completely diverged into "gammon chances + ~0 losing chances" and "losing chances + ~0 gammon chances", so one roll in the future lets you leverage the cube/no cube decision a lot better.
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10-24-2012 , 12:58 PM
Quote:
Originally Posted by TomCowley
When you wait and then want to double him out next turn (basically anything where you don't hit except 55/66 and he's entered on 6), your 10% "losing chances" don't exist, but ALSO those are spots where your gammon chances are microscopic, so it's a pure gain. After one sequence, the game has almost completely diverged into "gammon chances + ~0 losing chances" and "losing chances + ~0 gammon chances", so one roll in the future lets you leverage the cube/no cube decision a lot better.
This makes a lot of sense, as does Bill's analysis.

As ever, thank you everyone for your insight and thoughts!
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