Match Play

Forum Archive : Match Play

 
2-away/4-away: cube strategy

From:   Tom Keith
Address:   takeith@io.org
Date:   1 December 1996
Subject:   Re: How to play 4-away, 2-away?
Forum:   rec.games.backgammon
Google:   32A1F447.303F@io.org

Řystein Johansen wrote:
> How to cube at the score 4-away, 2-away?
> Can anyone give me a good lesson on useing the cube at this score?

Let me give this one a try ...

Leader's Strategy

At 2-away, Leader obviously would like to win a two-point game so he
can claim the match.  But a one-point win is also very good because
that would put the match score at 1-away, 4-away and Trailer would
then have to win *three* consecutive single games to win the match.

Trailer's break-even point for accepting/declining Leader's double
is when Leader's chances of winning the game are 83%.  To see why,
keep in mind that Trailer's strategy if he accepts will be to
immediately redouble and put the entire match on the line.  The 83%
represents Leader's match winning chances at 1-away, 4-away.

Leader wants to double as close to this 83% mark as he can.  He must
be careful about doubling too early because he doesn't want to give
Trailer a chance to turn the game around and steal the match.

With a significant gammon threat, Leader may wish to hold off
doubling until he sees if the gammon threat pans out.

Trailer's Strategy

When there is no gammon possibility, Leader's break-even point for
accepting/declining Trailer's double is when Trailer's game winning
chances are 80%.  (If Leader drops, his chance of winning the match
is .60.  If he takes, his match chances are (80% * .50) + (20% * 1.00)
= .60.)

So Trailer wants to double when his game-winning chances are
somewhere around 80%.  He's also happy to double a bit earlier than
this because he is hoping Leader will accept the double and make the
game worth two points.  Then Trailer will need just one more win after
this one to claim the match.

Doubling early might seem to be a dangerous tactic (because two points
is exactly what the Leader needs to win the match), but it is actually
less dangerous than a normal double because the Leader has no
effective redouble.

When gammons are a factor, Trailer has to be very aggressive with
the doubling cube.  Consider the situation from the Leader's point
of view.  Leader will be *very* reluctant to accept a double when
there is any kind of serious gammon threat -- he doesn't want to
lose a doubled gammon.  Leader will still be ahead in the match
if he drops a single point now.

On the other hand, Trailer *really* wants to get his double in
while Leader will still accept it.  So Trailer must have his finger
on the doubling trigger right from the start of the game.  As soon
as Trailer has even a modest lead in the game, he should consider
doubling.  And if the lead is accompanied by an increase in gammon
chances, then Trailer should double immediately.

At this score, gammons are worth a lot more for Trailer than they
are for Leader.  So Trailer will be playing towards gammonish
positions and Leader will be trying to avoid them.

Tom
 
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Match Play

1-away/1-away: advice from Bernhard Kaiser  (Darse Billings, July 1995)  [Long message] [Recommended reading]
1-away/1-away: advice from Stick  (Stick+, Mar 2007)  [GammOnLine forum]
1-away/1-away: and similar scores  (Lou Poppler, Aug 1995) 
2-away/3-away: playing for gammon  (Tom Keith, Feb 1996) 
2-away/4-away: Neil's rule of 80  (Neil Kazaross, June 2004)  [GammOnLine forum]
2-away/4-away: cube strategy  (Tom Keith, Dec 1996) 
2-away/4-away: practical issues  (Mark Damish, Jan 1996) 
2-away/4-away: trailer's initial double  (Kit Woolsey, Jan 1996) 
3-away/4-away: opponent's recube  (William C. Bitting+, Feb 1997)  [Long message]
3-away/4-away: racing cube  (Bill Calton+, Nov 2012) 
3-away/4-away: tricky cube decision  (Kit Woolsey+, July 1994) 
3-away/4-away: what's the correct equity?  (Tom Keith, Sept 1997) 
4-away/4-away: take/drop point  (Gary Wong, Oct 1997) 
5-away/11-away: redouble to 8  (Gavin Anderson, Oct 1998) 
7-away/11-away: volatile recube decision  (Kit Woolsey, May 1997) 
Both too good and not good enough to double  (Paul Epstein+, Sept 2007) 
Comparing 2-away/3-away and 2-away/4-away  (Douglas Zare, Mar 2002) 
Crawford rule  (Chuck Bower, May 1998) 
Crawford rule  (Kit Woolsey, Mar 1997) 
Crawford rule--Why just one game?  (Walter Trice, Jan 2000) 
Crawford rule--history  (Michael Strato, Jan 2001) 
Delayed mandatory double  (tem_sat+, Oct 2010) 
Delayed mandatory double  (Donald Kahn+, Dec 1997)  [Recommended reading]
Doubling when facing a gammon loss  (Kit Woolsey, Jan 1999) 
Doubling when opponent is 2-away  (David Montgomery, Dec 1997) 
Doubling when you're an underdog  (Stein Kulseth, Dec 1997) 
Doubling window with gammons  (Jason Lee+, Jan 2009) 
Free drop  (Ian Shaw, May 1999) 
Free drop  (Willis Elias+, Oct 1994) 
Gammonless takepoint formula  (Adam Stocks, June 2002) 
Going for gammon when opp has free drop  (Kit Woolsey, Jan 1998) 
Going for gammon when opp has free drop  (Kit Woolsey, Apr 1995) 
Holland rule  (Neil Kazaross, Apr 2010) 
Holland rule  (Kit Woolsey, Dec 1994) 
Leading 2-away with good gammon chances  (Douglas Zare, Feb 2004)  [GammOnLine forum]
Match play 101  (Max Urban+, Oct 2009) 
Matches to a set number of games  (Tom Keith+, Oct 1998) 
Playing when opponent has free drop  (Gilles Baudrillard+, Dec 1996) 
Post-crawford doubling  (Scott Steiner+, Feb 2004) 
Post-crawford doubling  (Maik Stiebler+, Dec 2002) 
Post-crawford doubling  (Gus+, Sept 2002) 
Post-crawford mistakes  (Rob Adams, Sept 2007)  [GammOnLine forum]
Post-crawford/2-away: too good to double  (Robert-Jan Veldhuizen, July 2004) 
Slotting when opponent has free drop  (onur alan+, Apr 2013) 
Take points  (fiore+, Feb 2005)  [GammOnLine forum]
Tips to improve cube handling  (Lucky Jim+, Jan 2010) 
When to free drop  (Dan Pelton+, Oct 2006) 
When to free drop  (Tom Keith+, July 2005)  [GammOnLine forum]
When to free drop  (Gregg Cattanach, Dec 2004)  [GammOnLine forum]
When to free drop  (Kit Woolsey, Feb 1998) 
When to free drop  (Chuck Bower, Jan 1998) 
Which format most favors the favorite?  (Daniel Murphy+, Jan 2006)  [GammOnLine forum]

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