Match Play

 Doubling when you're an underdog

 From: Stein Kulseth Address: stein@hal.nta.no Date: 18 December 1997 Subject: Re: Double when you are an underdog Forum: rec.games.backgammon Google: 67au0d\$8ls@nntp.nta.no

```Dean Gay writes:
> Kit's answer to a question I asked concerning volatility and doubling
> decisions got me wondering about something.  Is it possible for a
> situation to arise where it is correct to double when you are an
> underdog (excluding post-Crawford doubles and situations where the
> trailer redoubles because a loss at the current cube level would give
> his opponent the match)?

Yes, it's not that uncommon either. Say you are trailing at 4-away, 3-away
holding a 2-cube. By Kit's match equity table losing puts you at 17%, while
winning puts you at 60%. Thus by doubling you risk 17% to gain 40% and
given sufficient market losers you can justify doubling with as low as 30%
win chance, like this for instance:

24 23 22 21 20 19   18 17 16 15 14 13
x
x

o  o  o  o                                |2|
1  2  3  4  5  6   7  8  9  10 11 12

Also at this score the leader's 4-cube takepoint will be as high as 40%,
meaning that you will more often than not encounter situation in middle
game where you have significant market losers while being a small underdog.
You should be ready to redouble at this score as soon as you are close to
even with chances to gain an advantage.

Of course other more lopsided scores will offer even more clear-cut
examples of correct underdog doubles.

For fun here's an example of a correct underdog double from the one
leading the match, given that Kit's table applies to the two players
involved:

24 23 22 21 20 19   18 17 16 15 14 13
x
x
|1|

o     o
1  2  3  4  5  6   7  8  9  10 11 12

O has only a 39% chance to win this game. Doubling gives a 39% chance to
win immediately + 61% * 60% to win later from 2-away 3-away, total 75.6%
Not doubling gives 39% * 85% chance to win from 1-away 5-away and a 61% *
68% to win from 2-away 4-away, total 74.6%

Differences in skill levels should be taken into account, though, so that
if O is a weaker player, then the double is very clear, while if he is
the stronger player he should not double.
--
stein.kulseth@fou.telenor.no - http://www.fou.telenor.no/fou/ttkust
```

### Match Play

1-away/1-away: advice from Bernhard Kaiser  (Darse Billings, July 1995)
1-away/1-away: advice from Stick  (Stick+, Mar 2007)
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)
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)
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)
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)
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)
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)
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)
When to free drop  (Gregg Cattanach, Dec 2004)
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)