Cube Handling in Races

Forum Archive : Cube Handling in Races

Thorp count questions

From:   Chuck Bower
Date:   16 September 1999
Subject:   Re: Thorp Count questions
Google:   7rra27$eq2$

> 1) If the roller's count comes to 30 exactly, should you add 10% to
>    make it 33?

    How about adding 1.5.  This 'discontinuity' is probably the Thorp Count's
weakest feature.  Thorp is a mathematics professor and recognized that
simplicity should count for something, otherwise he would have made the
adjustment more complicated.

> 2) When adding 10%, should you round normally, always round up or always
>    round down?
>    a) 71, is the final count 78 or 79?
>    b) 75, is the final count 82 or 83?
>    c) 77, is the final count 84 or 85?

     If you don't round at all, you will often avoid #3 below.  That is
my suggestion.

> 3) If the non-roller is exactly 2 behind, is it a take or a pass? I've
>    seen both printed.

     I'm not sure what Thorp's original (and apparently difficult to find)
work said.  I use 'take', but it probably doesn't really matter.
The Thorp Count is a guide but it is far from 100% accurate.  It's better
than guessing and for bearoff's it is usually better than the popular
percentage methods.

> 4) I've read that a Thorp count is better in short races, but that the
>    racing lead in % is better for long races. Does anyone know roughly
>    where the breakpoint comes?

    Maybe you read something I wrote and thus this may not be an independent
answer.  Personally I think Thorp loses much of its reliability when there
are checkers outside the home board.  In addition, when there are only a
few checkers left (~5) for each side, it also suffers bigger uncertainties
(in general, IMO).

    Thorp's method was made popular by Bill Robertie in his two volume
ADVANCED BACKGAMMON.  He also covers other methods there which compliment
Thorp.  I recommend careful (re)reading of those books to help solve some
of these dilemmas.

     c_ray on FIBS
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Cube Handling in Races

Bower's modified Thorp count  (Chuck Bower, July 1997) 
Calculating winning chances  (Raccoon, Jan 2007) 
Calculating winning chances  (OpenWheel+, Nov 2005)  [GammOnLine forum]
Doubling formulas  (Michael J. Zehr, Jan 1995) 
Doubling in a long race  (Brian Sheppard, Feb 1998) 
EPC example  (adambulldog+, Jan 2011) 
EPC example: stack and straggler  (neilkaz+, Jan 2009) 
EPC examples: stack and straggler  (Carlo Melzi+, Dec 2008) 
Effective pipcount  (Douglas Zare, Sept 2003)  [GammOnLine forum]
Effective pipcount and type of position  (Douglas Zare, Jan 2004)  [GammOnLine forum]
Kleinman count  (Øystein Johansen+, Feb 2001) 
Kleinman count  (André Nicoulin, Sept 1998) 
Kleinman count  (Chuck Bower, Mar 1998)  [Recommended reading]
Lamford's race forumla  (Michael Schell, Aug 2001) 
N-roll vs n-roll bearoff  (David Rubin+, July 2008) 
N-roll vs n-roll bearoff  (Gregg Cattanach, Nov 2002) 
N-roll vs n-roll bearoff  (Chuck Bower+, Dec 1997) 
Near end of game  (Daniel Murphy, Mar 1997) 
Near end of game  (David Montgomery, Feb 1997) 
Near end of game  (Ron Karr, Feb 1997) 
One checker model  (Kit Woolsey+, Feb 1998) 
Pip count percentage  (Jeff Mogath+, Feb 2001) 
Pip-count formulas  (Tom Keith+, June 2004)  [GammOnLine forum]
Thorp count  (Chuck Bower, Jan 1997) 
Thorp count  (Simon Woodhead, Sept 1991) 
Thorp count questions  (Chuck Bower, Sept 1999) 
Value of a pip  (Tom Keith, June 2004) 
Ward's racing formula  (Marty Storer, Jan 1992) 
What's your favorite formula?  (Timothy Chow+, Aug 2012) 

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