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 | | |
> > | | | |
> > | | | 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.