2010-06-24 Match Play/Answer

The best play is 13/5.  Below is the ExtremeGammon evaluation followed by an excellent explanation by David Rockwell



From David Rockwell:  One of the things you want to do is to put blots in front of stripped points when you have to leave shots. Then your opponent needs to break the point to hit the blot. Look for this all the time and it will become natural. When I first saw this problem, I thought that this was key.

Getting hit on the mid point isn't that bad because it will leave a number of blots which give return hits. As I look closer, I see that the mid-point blot is not hit at all on the next turn. So, that is hardly the point of the problem. However, the four extra hits on the bar after 13-7, 13-11 are devastating. You have forfeited the double shot you would have gotten had you played 13-5 and your opponent has essentially escaped from the your prime.

You may or may not be able to take a double and your opponent may actually be too good if you dance. This is a huge swing and it more than offsets the advantage of 13-7, 13-11 on all of the rolls where you are missed. (Check the equity when opponent rolls a
6-1 after both 13-5 & 13-7, 13-11. Compare that difference to the swing after a dance.) Giving your opponent four extra jokers when he has a board this strong is something to be avoided. That's the key to this position.

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