Forum Archive : Terminology

"Squeeze", "trap play"

From:   Philippe Michel
Address:   michel@thomson-lcr.fr
Date:   21 February 1997
Subject:   Trap play questions
Forum:   rec.games.backgammon
Google:   E5yAqK.AMH@news.thomson-lcr.fr

| 8  O             |   |          X  X    |
| O  O             |   |                  |
| O  O             |   |                  |
| O  O             |   |                  |
| O  O             |   |                  |
|                  |   |                  |
|                  |   |                  |
|                  |   |                  |
|                  |   |                  |
|                  |   |                  |
|    O  X  X  X  X |   | X  X             | 2
|    O  X  X  X  X |   | X  X     X       |

   Score: O 5 away, X 3 away ; X on roll

What is the correct cube action ?

If X tries to close the 2 back men out, should he break the 8 point
only or the 7 and 8?

Kit Woolsey  writes:

> What is the correct cube action ?

If X doubles, O's takepoint is 15%.  I don't think O will win that
often (although it might be closer than one might think), so O should

Should X play on?  Not clear.  X's gammon chances aren't great, but
they do exist.  The downside isn't very great.  The only way X could
really get into trouble fast is if he goes for the squeeze and O rolls
the killing doubles immediately.  I think I would take a roll, and
then if I didn't immediately get a successful squeeze going I would

> If X tries to close the 2 back men out, should he break the 8 point
> only or the 7 and 8 ?

Neither!  The best squeeze technique here is to break the 7 point and
hold the 8 point.  This gains big if O rolls 5-1, and limits how far O
can escape if O is forced to run with one checker.

Brian Sheppard  writes:

Why not roll? After all, nothing dramatic will happen next turn.

I did an interactive rollout against JF Level 7, since JF Level 6
badly mishandles X's position. X wins 84.6%, with 24.9% gammons
against O's 15.4% wins and negligible gammons. X's cubeless equity
is 0.935, with a standard deviation of 0.028. It is hard to be
certain that X's equity when owning the cube exceed 1.000, but my
gut feel is that it does, since it seemed to me that about half
of X's losses occurred after X would have doubled O out of the game.

The tactics that X should pursue are as follows:

    0) Keep the 2 men back on the 14 ad 15 points unless forced
    to move off. (JF Level 6 moves these men.) If you are forced
    to move one of those men, prefer to move the 15 point, since
    keeping the 14 point man allows you to win if O rolls 6-6.

    1) Break the 7 or 8 points at the first opportunity. Give
    preference to breaking the 8-point first, since it is easier
    to break the 7 later.

    2) Break the other point at the first opportunity. JF Level 6
    will keep both outside points.

    3) Use the blot on the 10 point as spare timing in case you have a
    roll that doesn't break the outside priming points. Note that if
    the opponent had a board threat then you would not be able to
    use this resource, since an outfield hit could be fatal.

    4) Hit all blots. Given the choice between closing out with one
    man on the bar and having a 5-point board with 2 men, you should
    choose to hit 2 men, even if it means leaving a blot. Again, the
    opponent's crunched board makes this tactic possible.

    5) Do not be afraid to slot the ace point, or cover it, if
    that will allow you to keep the hitting checkers in place. After
    all, you intend to cover that point anyway!

    6) Double O out if you are forced to move the back checkers.
    By that point there is little hope of winning a gammon.

X's ownership of the cube is very important, as is O's weak board.
Without those two factors the tactics outlined above would not work.

For this tournament situation you should cash, possibly after letting
a roll or two go by, just to see how things develop. If any
awkwardness appears, however, you should cash. If the score were
reversed, then playing on would be clear.


tptron  writes:

I think the trap (forcing him to leave one man back and hit it) in
this case is a much better plan then the squeeze. It of course,
depends on the rolls. If he can force hin to break that point he can
hopefully close the table and have a chance (although unlikly) at the

Brian Sheppard  writes:

Tom Keith asks:
> Squeeze?

The equivalent of exploiting zugzwang in chess: to take advantage
of the opponent's compulsion to move any playable roll.

> Trap play?

A trap play is a deliberate attempt to squeeze an opponent off of
his anchor, so that the trapper can close out any blots thereby
exposed and win a gammon.
Did you find the information in this article useful?          

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



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