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GNU Backgammon
Quasirandom dice in rollouts

Here is Joern's explanation from the gnubg archives.
QuasiRandom Dice are used to reduce the element of luck in rollouts.
Instead of selecting purely random dice, gnubg will ensure a uniform
distribution of the first roll of the rollout. If 36 trials is requested,
one game will start with 11, two games with 21, two games with 31, etc.
In general, if n * 36 games is requested, n games will start with 11, 2*n
games with 21 etc. This is called _rotation_ of the first roll. Similarly,
if n*1296 trials is requested, the second roll will be rotated, such that
n games will start with 1111, 2*n games with 1121, 4*n games with 2121,
etc. The third roll be also be rotated if the number of trials is
proportional to 46656.
Suppose a user stops a 1296 trial rollout after 36 games. The 36 games
would have had the following rolls for the first two rolls of each game:
1111, 2111, 1211, 3111, 1311, ..., 6611 Obviously such a rollout
will give skewed results since the second roll was 11 for all games! To
avoid this problem gnubg will randomise the sequence of rolls such that
it is guaranteed that for any sample of 36 games you have exactly one
game with first roll 11, exactly one game with second roll 11, etc. This
is called _stratification_.
gnubg will actually also rotate and stratify rollouts where the number
of trials are not multiples of 36, 1296, etc. The distribution of rolls
is obviously not uniform any longer in this case, but it will still
provide some reduction of the luck, i.e., no 37 trial rollout will have
3 games with a initial 66.




GNU Backgammon
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 Batch analysis tool (Øystein Johansen, June 2004)
 Cache size (Ned Cross+, Mar 2004)
 Compiling for Windows (Øystein Johansen, Jan 2002)
 Edit mode removing checker from bar (Scott Steiner+, May 2003)
 Entering an annotated match (Albert Silver, Dec 2003)
 Error rates: Gnu vs. Snowie (Raccoon, Mar 2006)
 Evenply/oddply effect (Raccoon, Nov 2004)
 Evenply/oddply effect (Tom Keith+, Oct 2003)
 Evenply/oddply effect (Scott Steiner+, Dec 2002)
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 Gnu 0.13 versus Jellyfish and Snowie (Torsten Schoop, Aug 2003)
 Gnu 0.13 vs. Snowie 4 (Albert Silver, June 2003)
 Gnu 0.14 vs. Jellyfish (Michael Howard+, July 2003)
 Gnu versus Snowie and Jellyfish (Michael Depreli, Oct 2005)
 How luck factor is calculated (Gregg Cattanach, Aug 2002)
 How rollouts work (Gary Wong, July 1999)
 How to enter an illegal move (Øystein Johansen, Aug 2003)
 Importing .gam files (PAR+, Mar 2005)
 Importing PartyGammon matches (rew+, July 2006)
 Improving your game using GnuBG (D.U.G.+, Nov 2002)
 Installing on Windows (maareyes, Oct 2001)
 Interpreting JSD's (Adrian Wright+, Feb 2005)
 JSD's and confidence intervals (Daniel Murphy+, Jan 2005)
 Logging rollouts (Øystein Johansen, Oct 2004)
 Luck rate (Kees van den Doel+, May 2002)
 MWC versus Equity (EMG) (Ken+, Apr 2005)
 Manually entering first roll (Andreas Graf+, Apr 2005)
 Match equity tables (Raccoon, July 2005)
 Personal reflections (Louis Nardy Pillards, Sept 2002)
 Playing two computers against each other (Stanley E. Richards+, Mar 2008)
 Python scripting (Øystein Johansen+, Nov 2004)
 Quasirandom dice in rollouts (Ian Shaw, Mar 2004)
 Question marks in game list (Jim Segrave, July 2005)
 Questions and answers (Jim Segrave+, Jan 2003)
 Questions and answers (Jørn Thyssen, Aug 2002)
 Restarting a rollout with different settings (Jim Segrave, Apr 2005)
 Restarting a rollout with different settings (RobertJan Veldhuizen, Apr 2004)
 Rollout settings (geoff arnold+, Apr 2007)
 Rollout settings (Stick+, Nov 2005)
 Rollout settings (RobertJan Veldhuizen, Mar 2004)
 Rollout settings (Ian Dunstan, Aug 2003)
 Rollout settings for the impatient (RobertJan Veldhuizen, June 2004)
 Running rollouts in background (Bruce+, Apr 2004)
 Saving rollout results from commandline interface (Jeremy Bagai+, Apr 2006)
 Saving rollouts (Mislav Radica+, May 2006)
 Setting GnuBG's playing strength (JP White, Sept 2001)
 Setting skill level (Jim Segrave, Apr 2004)
 Setting up and saving a rollout (Albert Silver, Dec 2003)
 What's GNU? (Gary Wong, Oct 2001)
 Which player is player 0? (Neil Kazaross+, Oct 2004)
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