Cube Handling

Forum Archive : Cube Handling

Woolsey's law

From:   PersianLord
Date:   12 March 2008
Subject:   Woolsey's law
Forum:   BGonline

We have an ongoing discussion in DailyGammon on Woolsey's law.  I claim
that we can ALWAYS apply Woolsey's law and that we can interpret
double/take situation with the help of it. Bert and Hardy claim otherwise
and say that this situation (double/take) is not included in Woolsey's law.

Who is right?

Daniel Murphy  writes:

Kit Woolsey, September 21, 1996 []:

    For those of you who aren't familiar with my rule, it is as follows: If
    you aren't ABSOLUTELY sure whether the position is a take or a pass,
    then it is ALWAYS correct to double. I'm not kidding! I follow this
    rule religiously in actual play, and any player who does likewise will
    see his results improve tremendously.

That's emphatic and clear. Note that it applies only to doubling decisions,
not take decisions. Note that following this rule does not guarantee that
your doubling decisions will always be right.

Kit continues:

    Note that the converse is not necessarily true -- you may be absolutely
    sure it is a take and yet it is still correct to double, provided it is
    a very volatile position.


The Woolsey rule isn't about what your opponent thinks he should do; it's
all about what you think he should do.

You have a cube decision. You ask yourself: Is it a pass or a take? You
answer yourself: Not sure! What does that tell you? It tells you that
subject to the limitation of your own ability to judge a position, the
take/pass decision is close.

So, either your opponent has a bare take, in which case you should double,
because you can't be not good enough to double if you're opponent has only
a bare take, and you can't be too good to double if your opponent has a
take; not doubling has to be an error.

Or, your opponent has a bare pass, in which case you should double, because
you can't be to be too good to double if your opponent has only a marginal
pass, and you can't be not good enough to double if your opponent should

I'll bet every aspiring player went through a phase where cube decisions
were confused in this way: Maybe I'm not good enough to double ... wait, I
think he should pass ... wait, maybe I'm too good! ... oh, but what if he
takes? The Woolsey rule cuts through that crap. It says: focus on the
take/pass decision. If you're not sure about the take/pass decision,
double. Always. What can happen?

Either (1) Your estimate isn't too bad.

Then either (a) It's a close take. You're glad you doubled. You're
especially glad if opponent passes. Either way, you gain. Or (b) It's a
close pass. You're glad you doubled. You're especially glad if opponent
takes. Either way, you gain.

Or (2) Your estimate is off.

Then either (a) It's too good to double. Alas, your double was a mistake.
However, it could well be that your mistake was not large; after all, you
thought opponent might have a take. And if you thought he might have a
take, maybe he will take, probably a much greater error than your double.
Or (b) It's not good enough to double. Again, your double was a mistake.
But again, your mistake might not be large, since you thought opponent
might have a pass. And again, if you thought he might pass, maybe he will!

Matt Cohn-Geier  writes:

I suppose I'll come out and state my opinion: Woolsey's Law doesn't always

Suppose you are up in a match, -2,-4. You have very good gammon chances.
You're not sure whether the position is ND/T, ND/P, or maybe even D/T or
D/P, but you figure there is a lesser chance of the last two. And you don't
know whether your opponent will take or drop, since he's as clueless as you
are, but it doesn't figure to be a gross blunder one way or the other. On
the other hand, if you make a mistake and double when it's really ND/T, and
your opponent takes, you've likely given up a lot more equity than he would
have if he passed.

I'm certainly not doubling. And that's just an example, the specifics may
be changed.

I'll also add a corollary, which I guess I might attribute to Robertie:
Always do your best to determine what the correct cube action is for both
sides before making a decision.

Stick  writes:

First thing you should do is read, or reread as the case may be, Woolsey's
Doubling Rule:

I believe almost everything I'm going to mention has already been stated
but I'd like to summarize more concisely with an example as to when and why
Woolsey's rule should be employed.

The biggest drawback I thought of when first reading about Kit's rule is
that you're limited by your own playing strength. Just because I'm not sure
whether it's a take or a pass doesn't mean Neil doesn't know for 100%
certainty the D/ND T/P decision. I do think the rule is useful however for
decent players and make use of it myself. I would only caution weaker
players about using it because they could be chunking off large sums of
equity sending over way early cubes (and then having to play out that
position being the weaker player!) I think it's much more constructive to
take the extra time to get under the T/P decision than to do as Kit says
"Readers who have watched me play may notice that I often double a
complicated position with apparently no thought. That's fine if you're Kit
and you have enough bg experience under your belt to understand positions
at a glance, but I wouldn't recommend it for Average Joe BG Player.

Kit also lists 'the four possible cube strategies' for any position:

   1. Not good enough to double, take
   2. Double, Take
   3. Double, Pass
   4. Too good to double, pass

Kit himself realizes his law isn't 100% foolproof in stating, "It is true
that there are certain exceptions in match play when you are ahead in the
match and the turn of the cube will put you out or nearly out, but in all
other situations the law applies."

In an example borrowed from Douglas Zare's article on Woolsey's Rule in
Match Play
we have the following position.

    Match to 3: X leads 1-0.  X is on roll.

     24  23  22  21  20  19      18
    |         O   O   O   O |   | O                     |
    |         O   O   O   O |   | O                     |
    |                       |   |                       |
    |                       |   |                       |
    |                       |   |                       |
    |                       |   |                       |
    |                     X |   |                       |
    |             X       X |   |                       |
    | O       X   X       X |   |                       |
    | O   X   X   X   O   X |   |                       |
    | O   X   X   X   O   X |   | X                     |
      1   2   3   4   5   6       7

Is it a take? Is it a pass? The problem is no matter what decision your
opponent makes, right or wrong, you've made a blunder. You'd be much better
off holding the cube whether or not your opponent takes or passes in this
position thus making an exception to Woolsey's rule.

We should resign ourselves to normal money-like match scores when using the
Woolsey rule for the most part. It works exceptionally well for $$$, no
doubt about it. I personally would rather double a shade early, as I think
Kit does, instead of waiting.

Kit also states, and I'm not sure if he's the first to say it or not,
though it has been etched in my brain for as long as I can remember, With
correct cube play, I believe that at least 2/3's of initial doubles should
be taken.  For the record this is pretty accurate. I have many stats I've
ripped from my GNU v. SW series and the fact that 2/3rds of the initial
doubles should be taken holds water. So next time you're considering
passing that initial double, make sure you know what you're doing!


Chuck Bower  writes:

> I would only caution weaker players about using it because they could be
> chunking off large sums of equity sending over way early cubes (and then
> having to play out that position being the weaker player!) ....I wouldn't
> recommend it for Average Joe BG Player.

Well, isn't it possible that "Joe" is giving up just as much or even more
equity by not doubling? You gotta learn sometime.

I've always been impressed by the arguments good players try and give weak
players. Quite often it goes something like "(I don't want to see a cube
coming over in a gammonish position, so,) weaker player, the best thing for
YOU to do is to leave it be."
Did you find the information in this article useful?          

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


Cube Handling

Against a weaker opponent  (Kit Woolsey, July 1994) 
Closed board cube decisions  (Dan Pelton+, Jan 2009) 
Cube concepts  (Peter Bell, Aug 1995)  [Long message]
Early game blitzes  (kruidenbuiltje, Jan 2011) 
Early-late ratio  (Tom Keith, Sept 2003) 
Endgame close out: Michael's 432 rule  (Michael Bo Hansen+, Feb 1998)  [Recommended reading]
Endgame close out: Spleischft formula  (Simon Larsen, Sept 1999) 
Endgame closeout: win percentages  (David Rubin+, Oct 2010) 
Evaluating the position  (Daniel Murphy, Feb 2001) 
Evaluating the position  (Daniel Murphy, Mar 2000) 
How does rake affect cube actions?  (Paul Epstein+, Sept 2005) 
How to use the doubling cube  (Michael J. Zehr, Nov 1993) 
Liveliness of the cube  (Kit Woolsey, Apr 1997) 
PRAT--Position, Race, and Threats  (Alan Webb, Feb 2001) 
Playing your opponent  (Morris Pearl+, Jan 2002)  [GammOnLine forum]
References  (Chuck Bower, Nov 1997) 
Robertie's rule  (Chuck Bower, Sept 2006)  [GammOnLine forum]
Rough guidelines  (Michael J. Zehr, Dec 1993) 
Tells  (Tad Bright+, Nov 2003)  [GammOnLine forum]
The take/pass decision  (Otis+, Aug 2007) 
Too good to double  (Michael J. Zehr, May 1997) 
Too good to double--Janowski's formula  (Chuck Bower, Jan 1997) 
Value of an ace-point game  (Raccoon+, June 2006)  [GammOnLine forum]
Value of an ace-point game  (Øystein Johansen, Aug 2000) 
Volatility  (Chuck Bower, Oct 1998)  [Long message]
Volatility  (Kit Woolsey, Sept 1996) 
When to accept a double  (Daniel Murphy+, Feb 2001) 
When to beaver  (Walter Trice, Aug 1999) 
When to double  (Kit Woolsey, Nov 1994) 
With the Jacoby rule  (KL Gerber+, Nov 2002) 
With the Jacoby rule  (Gary Wong, Dec 1997) 
Woolsey's law  (PersianLord+, Mar 2008) 
Woolsey's law  (Kit Woolsey, Sept 1996) 
Words of wisdom  (Chris C., Dec 2003) 

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