Forum Archive : Strategy--Backgames

Which anchor to break

From:   Brian Sheppard
Date:   19 May 1997
Subject:   Re: Anchors Aweigh
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.

Did you find the information in this article useful?          

Do you have any comments you'd like to add?     



After an early blitz attempt  (Daniel Murphy, Apr 1997) 
But they're so much fun!  (Laury Chizlett+, Oct 2000) 
Checker problem  (David Montgomery+, May 1995) 
Defending against a backgame  (KL Gerber+, Jan 2003)  [Long message]
Defending against a backgame  (Michael J. Zehr, Jan 1995) 
How many men back?  (Brian Sheppard, July 1997) 
Play for a backgame from the start?  (Alan Webb+, Dec 1998) 
What is a backgame?  (Daniel Murphy, Apr 2001) 
When to double  (David Montgomery, May 1995) 
Which anchor is best?  (Kit Woolsey, July 1996) 
Which anchor to break  (Brian Sheppard, May 1997) 
Which anchors are best?  (sebalotek+, Jan 2012) 
Which anchors are best?  (Adam Stocks, Apr 2002) 
Which anchors are best?  (Mary Hickey, Mar 2001) 
Which anchors are best?  (Jerry Weaver+, Apr 1998) 
Which anchors are best?  (Chuck Bower, Jan 1997) 
Which anchors are best?  (Marc Gray, Nov 1995) 

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