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BGonline.org Forums
Advanced Backgammon part 24A
Posted By: Chuck Bower In Response To: Advanced Backgammon part 24A (Matt Cohn-Geier)
Date: Thursday, 25 June 2009, at 4:33 p.m.
231 & 232
The difference here is that in the first of these two, safety has extra importance. In the second, a speedy bearoff (relatively speaking) gains value.
A Woolseyism is: "Find the die that won't clear a checker from the highest occupied homeboard point and put spares on the corresponding numbered point." (An example is worth a lot here!) Five's can't be played from the 6-point, so put spares on the 5-point.
So this argues for 9/5, 8/5 in problem #231. (Note that both 5-5 and 6-6 will be safe on Blue's next roll.)
In the second problem, Blue would rather bear off checkers with a 4-die than clear the 6-point. So here it looks like 8/4, 9/6 will lead to a faster bearoff.
It is worth noting (IMO) that moving the checker off the 11-point makes it more likely that checkers bear in deep into the homeboard. And 11/4 blots on 6-6 next turn. 8/4, 6/3 looks palatable at first glance, but this blots on 5-5 next turn.
Summary: 231: 5(2). 232: 8/4, 9/6.
233
Hit avoidance is the name of the game here. Three deuces are reasonable at first glance: 5/3, 6/4, 7/5.
Let's make 6/4 the baseline and compare the other two to that one. 5/3 is better than 6/4 if White enters and Blue rolls 6-4. 6/4 is better if Blue's next roll is either 5-5, 4-4 or 3-3, regardless of whether White enters or not.
Looks like 6/4 is better than 5/3.
How about 6/4 vs. 7/5? 7/5 pays off immediately 5 1/2 % of the time. 6/4 pays off to 6-4 and 6-5 next turn IF White has entered and can roll a 6 (or subsequently enters w/ 6-1). That's (4/36)*(11/36)*(11/36) + (4/36)*(25/36)*(2/36) or (484+200)/36^3. (Hey, did we get lucky? 684/36 = 19 as people who live their lives doing rollouts know. :) So 19/1296, which is about 1 1/2% -- much better than 5 1/2%.
233: 6/4.
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