Match Play

Forum Archive : Match Play

Post-crawford/2-away: too good to double

From:   Robert-Jan Veldhuizen
Date:   3 July 2004
Subject:   Re: Post-Crawford curiosity.

Paul Epstein asked:
> Two questions which are interesting (to me) about the Post-Crawford
> score of 2-away, 1-away.
> 1) Which exchanges are too good for the trailer to double? (Trailer
> 31, leader 62) is such an exchange.  Does anybody know of any others?

I'm currently investigating these with GNUBG rollouts. There's lots of
dice sequences to consider though. Trailer has 15 different opening
rolls, Leader has 21 different replies. Also, sometimes it's far from
clear what the best moves are, especially given the weird matchscore

Here's a few results for the openings 3-1, 6-1 and 6-4 and all replies
(all candidate moves rolled out, best one made). For 6-4, it seems
24/14 is slightly the best play for Trailer to start with, but I also
rolled out everything for 24/18 13/9 and 8/2 6/2.

I should note though, that slight biases in GNUBG's cube play can have
significant effects, so the rollout results might not be very

Still interesting though, that according to my GNUBG rollouts (0-ply
play, 2-ply 100% cube) there are really much more too good sequences
than most players assume, f.i. also after a 6-1 opening.

Trailer opens 3-1: 8/5 6/5

Only if Leader replies with 1-1, 2-2, 3-3 or 6-6, he can take.

After 4-4(!), 3-1, 4-2 and 6-1 it's a PASS.

After all other rolls (13), it's TOO GOOD (!). 4-1 (13/8) is the worst
reply for Leader and leaves trailer too good with a 1.07 EMG equity!
Trailer opens 6-1: 13/7 8/7

2-1, 4-1, 5-1, 3-2, 5-2, 6-2, 4-3, 6-3, 5-4, 6-4 and 6-5 all (11
rolls) leave Trailer TOO GOOD (!). Usually it's not more than 1.02 too
good though.
Trailer opens 6-4: 24/14 seems best

No too good situations after this one.
Trailer opens 5-3: 8/3 6/3

A 4-1 reply leaves Trailer just too good (1.01); other replies not
checked yet.

> 2) Assuming perfect players, who is the match favourite if the trailer
> opens with the 31 perfecta?

That's an interesting question; it seems very close. I got a 1.014 EMG
equity for an opening 3-1, so it seems like Trailer is a tiny favorite
to win the match then.

>  In other words, is the trailer's equity
> from the too-good-to-double scenarios greater than the leader's equity
> from the possibility of replying with non-55 doubles?  (Any non-55
> doubles reply to 31 makes the leader the favourite, I believe.)

A 4-4 reply also leaves trailer the favourite and he should cash then.

_ orba
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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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