From: ekw@world.std.com (Elliott C Winslow)
Newsgroups: rec.games.backgammon
Subject: Re: 53 then 64 opening
Summary: It's debatable, but you have to see why.
Date: 16 Oct 92 03:05:54 GMT
Organization: The World Public Access UNIX, Brookline, MA

In article <s4aPsB2w163w@peewee> peewee@infoserv.com (Philip Stromer) writes:
>There is no logical reason NOT to play 24-14.


|24 23 22 21 20 19| |18 17 16 15 14 13|
|X  .  O  .  .  O | | .  O  .  .  .  X|
|X     O        O | |    O           X|
|               O | |                X|
|               O | |                X|
|                 | |                X|
|                 [ ]                 |
|               X | |                O|
|               X | |                O|
|               X | |    X           O|
|O              X | |    X           O|
|O  .  .  .  .  X | | .  X  .  .  .  O|
|1  2  3  4  5  6 | | 7  8  9 10 11 12|
X to play 6-4

There are a *lot* of good, logical reasons for playing 24-18, 13-9 over
24-14.  They just require looking morely deeply than your one-roll
hit-or-not-hit analysis.

Just on the basis of who makes out better in exchanges of hits, the
split/down play looks better.  If I hit you back 1/3 of most of the times
you hit me, then I'm almost equal right there.  [One reason why this 6-4 is
closer than 6-3 or 5-4 or 6-2, because with those the run leaves more
shots.]

But the "big swing" that makes the top players (well, some of them! :-)
prefer the split/down plays, is that it is considered that there is *MORE*
*TO* *GAIN* by splitting.  If you end up with the bar-point, you've gained
far more than most any other possibility; and an exchange of hits on the 18
also means that he is falling back in the race and the number of men back
(two different, though obviously related, factors).

When I first met Gerard Duguet-Grasser in Paris in 1987, he was very good
but relatively inexperienced and "green" regarding some concepts.  I showed
him how it might be right to split with 4-3 after an opening 4-2:

|24 23 22 21 20 19| |18 17 16 15 14 13|
|X  .  .  O  X  O | | .  O  .  .  .  X|
|         O     O | |    O           X|
|               O | |                X|
|               O | |                X|
|                 | |                 |
|                 [ ]                 |
|               X | |                O|
|               X | |                O|
|               X | |    X           O|
|O              X | |    X           O|
|O  .  .  .  .  X | | .  X  .  X  .  O|
|1  2  3  4  5  6 | | 7  8  9 10 11 12|

You do this by applying partitioning, i.e. consider the likelihood of the
different possibilities (O points, O misses and X covers, O misses and X
doesn't cover, O hits loose and X hits, O hits loose and X misses, O hits
2, etc. etc.  And then you do the same thing with the two-down play.

It comes out tantalizingly close.  Of course, it involves some extremely
loose approximations, but that's the way it is.  And I don't mean loose as
in biased, I just mean how can you know.

By the way, I think it was Roger Low who really sank in on this sort of
principle, along with Paul Magriel of course;  in any case I remember seeing
Roger doing this play more than once in recorded matches.  It could be a
question of style and tournament situation as well, but as I started out
saying in the summary:

IT'S THE **CONCEPT** THAT YOU HAVE TO TRY TO GRASP.

--Elliott