Backgammon Strategy--Backgames

Strategy--Backgames

Which anchor to break

From:   Brian Sheppard
Address:   brians@mstone.com
Date:   19 May 1997
Subject:   Re: Anchors Aweigh
Forum:   rec.games.backgammon
Google:   01bc6462$97109430$3ac032cf@polaris

Stephen Hubbard wrote: > Stuart Katz, MD wrote: > > +24-23-22-21-20-19-+---+18-17-16-15-14-13-+ > > | X O X X O | X | O O O | > > | X O X X O | | O O O | > > | O | | | > > | O | | | > > | | | |[64] > > | | | O | > > | X X X X | | O | > > | X X X X | | O | > > +-1--2--3--4--5--6-+---+-7--8--9-10-11-12-+ > >money game; cube centered; X has one on bar; X to play 61 > > First of all I would keep the anchor on 23 because of being so far > behind in the race--51 pips after this move. Abandoning this anchor > seems gives more of a chance for o to bypass the more advanced anchor > without getting hit. > > So the question is whether to leave 21 or 20. > JF recommends leaving 21. Why would this produce more equity? My copy of JF (version 2) plays bar/24, 23/17 at every level, including rollouts. Perhaps you are using a different version? > Leaving 21 seems to put more pressure in the outfield and maintain > more contact . > Keeping 20 seems to help future escape chances. > I would think that this move would help timing also by giving more > escaped checkers to work with. Sound explanation or not? I don't agree. Breaking the 23 point is definitely best. The fundamental issue in this type of position is timing. How long can X preserve his anchors? How long can X preserve his board? When will X get a shot? Looking at X's position, we see that it is about to crack someplace. X has to give up an anchor immediately. And X's board is compromised by the gap on his 5 point. This is important to the proper evaluation of this position because it means that X has a lot of work to do even after hitting O. On the other side of the table, O is not in danger of cracking. Sure, there are rolls that force O to give up a point, and even leave a blot. But those blots are indirect shots, and being hit is not immediately decisive because X has to bring his army around and O keeps all his men in play. So timing is bad for X. And this leads to a clear decision for which anchor to keep: keep the high anchors. I have no doubt that there are positions where this rule fails, due to overriding tactical urgencies, but I don't see any such factors here. The biggest danger is O scrambling home while X is on the bar, so X never gets more than a few indirect shots. But X is as likely to suffer that fate if he breaks another anchor. This decision is supported by rollouts. I won't give exact numbers, because I believe JF doesn't play these positions very well. But the general outline of the game is as follows: 1) No matter what X plays, O should double immediately. 2) X has a clear take after 23/17, and also a take after the other plays but it is close. 3) O should hit that man on the 17 point, because 4) X should try to cover that man on the 17 point, which will hinder O's entry and facilitate X's escape. X is quite likely to be forced to give up another anchor, so it is very important to keep a passageway for the men as they come out. 5) In general, X should try to play with a minimum of blots, since staying on the bar will allow O to scamper home. 6) O should, of course, play to minimize blots as well. This is even more important than minimizing shots, since with X's 5 point open O can take a redouble with one man on the bar, but would have to drop if a second blot were exposed. The problem with 21/15 and 20/14 is that the 15 and 14 points are not critical for O since they are easy to bypass. But if X establishes the 17 point it will be a pain in the neck for O. Brian

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