Rollouts

Forum Archive : Rollouts

 
Truncated rollouts

From:   Gregg Cattanach
Address:   gcattanach@prodigy.net
Date:   13 October 2002
Subject:   Re: Truncated rollouts
Forum:   rec.games.backgammon
Google:   Ennq9.1040$xU7.176@newssvr19.news.prodigy.com

> Could someone explain to me what truncated rollouts are?

A truncated rollout just makes the number of moves specified and then uses
the bot's evaluation function at the position obtained to accumulate the
results that go into the rollout.   For play vs. play comparisons
(especially where both sides have simple or difficult plays), truncated
rollouts probably give pretty reasonable results.  *(Some caution is
required when one side has very simple plays and the other is very
difficult, like containment positions.  In these the errors will pile up on
one side, and that can skew the results.)  To get the same accuracy for
full rollouts that you get from a truncated rollout you usually have to do
40 times the number of games because a fully played out game has so much
more 'noise' involved.  And, of course, full rollouts take dramatically
longer. So given limited CPU resources, on checker play comparisons
truncation is probably quite useful and gives up only a small amount of
accuracy.  (I usually truncate at 11 moves.)

For cube action rollouts, the absolute equity value is of critical
importance, so any error the bot has on estimating the absolute equity of
the resulting truncated position will find its way into the rollout
results. Most people would say that truncation for cube action is probably
the wrong way to go; full rollouts are required.  Checker plays we're
trying to answer which play is best, and we're not too worried what the
absolute value of the best play is.  For cube action the absolute equity is
the only important value.

Gregg C.
 
Did you find the information in this article useful?          

Do you have any comments you'd like to add?     

 

Rollouts

Advice  (David Montgomery, Apr 1996)  [Long message]
Cautionary tale  (Kit Woolsey, Sept 1995) 
Combining rollouts  (Gregg Cattanach+, Dec 2003)  [GammOnLine forum]
Confidence intervals  (Bob Koca, Nov 2010) 
Confidence intervals  (Timothy Chow, May 2010) 
Confidence intervals  (Gerry Tesauro, Feb 1994) 
Cubeless vs centered-cube rollouts  (Ron Karr, Dec 1997) 
Duplicate dice  (David Montgomery, June 1998) 
How reliable are rollouts?  (David Montgomery, Aug 1999) 
Level-5 versus level-6 rollouts  (Michael J. Zehr, June 1998) 
Level-5 versus level-6 rollouts  (Chuck Bower, Aug 1997) 
Positions with inaccurate rollouts  (Douglas Zare, Oct 2002) 
Reporting results of rollouts  (David Montgomery, June 1995) 
Rollout settings  (Lokicol+, Apr 2010) 
Settlement limit  (Michael J. Zehr, Apr 1998) 
Settlement limit  (Kit Woolsey, Dec 1997) 
Settlement limit in races  (Alexander Nitschke, Dec 1997) 
Some guidelines  (Kit Woolsey, Apr 1996) 
Standard error and JSD  (rambiz+, Feb 2011) 
Standard error and JSD  (Stick+, Oct 2007) 
Systematic error  (Chuck Bower, Oct 1996) 
Tips for doing rollouts  (Douglas Zare, June 2002) 
Truncated rollouts  (Gregg Cattanach, Oct 2002) 
Truncated rollouts: pros and cons  (Jason Lee+, Jan 2006)  [GammOnLine forum]
What is a rollout?  (Gregg Cattanach, Dec 1999) 

[GammOnLine forum]  From GammOnLine       [Long message]  Long message       [Recommended reading]  Recommended reading       [Recent addition]  Recent addition
 

  Book Suggestions
Books
Cheating
Chouettes
Computer Dice
Cube Handling
Cube Handling in Races
Equipment
Etiquette
Extreme Gammon
Fun and frustration
GNU Backgammon
History
Jellyfish
Learning
Luck versus Skill
Magazines & E-zines
Match Archives
Match Equities
Match Play
Match Play at 2-away/2-away
Miscellaneous
Opening Rolls
Pip Counting
Play Sites
Probability and Statistics
Programming
Propositions
Puzzles
Ratings
Rollouts
Rules
Rulings
Snowie
Software
Source Code
Strategy--Backgames
Strategy--Bearing Off
Strategy--Checker play
Terminology
Theory
Tournaments
Uncategorized
Variations

 

Return to:  Backgammon Galore : Forum Archive Main Page