GNU Backgammon

Forum Archive : GNU Backgammon

Questions and answers

From:   Jim Segrave
Date:   15 January 2003
Subject:   Re: GNU questions and suggestions.

> 1. Under advanced options what does cache size mean?  what setting is
> best for max speed?

When analysing a match or evaluating a move, gnubg often is
calculating possible rolls and resulting moves and positions, then
evaluating the equity for these positions. It can cache the results of
these calculations, so that, if it later has to evaluate the same
position, it can use the saved answers. Setting it to larger values
will make some things, particularly analysis of games somewhat
faster. The more memory your computer has, the larger a setting you
can try, although somewhere around 100,000 entries or so, I don't
think you'll see any real improvement.

> 2. Under advanced options what does  delay mean?  what setting is best
> for max speed?

Sets the speed at which moves can be made. (does not affect rollouts),
lower = faster, but only if gnubg is playing against itself or you are
a lightning player.

> 3. Under rollout settings what does reduced evaluations mean?  what is
> the trade off of speed vs best answer?

Only a percentage of possible future plies are evaluated. This saves
time, but for the most accurate answers, you don't want this.

> 4. Under rollout setting what are the new tabs First play, First play(1)
> etc?

You can do a rollout telling gnubg to use one set of playing
parameters (say 2 ply) for the first few moves, then later in the
rollout of a game, shift to a less stringent (0 ply) but faster
analuysis, on the grounds that mis-evaluations on play 6 or 10 moves
into the game are unlikely to produce large effects. So, you might set
the 'Enable separate evaluations' checkbox and tell it to change
evaluations after 6 moves. For the first 6 moves, it would make plays
using the First Play tabs, after 6 moves it would use the settings on
the 'Later Play' tabs.

You can, if you wish, also have the player 0 and player 1 moves use
different choices for how moves are selected, in which case there are
separate pages for the two sides.

Finally, if you want to do a truncated rollout - for example, you
might let each game be rolled out for the next 11 moves, then use an
evaluation of the resulting position to estimate
wins/gammons/backgammons etc. You can decide how this final position
will be evaluated by setting the Truncation point page (or you can
disable truncation and have every game rolled out to completion).

> 5. How do you turn the sound off?

The easiest way is go to Edit/Enter command and put the command
Set sound enable off
in the dialogue box. Then click the Settings/save settings option to
make it remember this for the future.

> 6. What are the things under the 'Train' tab and how do you use them?

This is for training the neural net which is the heart of gnubg's
evaluator. I can't claim to know how you would use this, but I can
say, that unless you know a lot about neural nets and backgammon and
have access to a lot of computers or helpers, you don't want to use
these options. I think the last change to the neural net used several
hundred thousand rollouts to help improve the neural net.

> 7. Under File/New what is weights? It is set at 128.  Would setting give
> max best answer?

This affects the way the neural net works. You *really* don't want to
change this.

Jim Segrave 

Jørn Thyssen  writes:

> 7. Under File/New what is weights? It is set at 128.  Would setting give
> max best answer?

It's for generating new random weights. You're better off with the
current ones.

> 8. Under race theory what is 'One sided rollout'?

Similar to one sided bearoff databases. Instead of calculating an
exact one sided bearoff distribution, we perform a rollout looking at
one side only. This gives a approximative one sided bearoff
distribution. The approximative one sided bearoff distributions for
each side are combined similar to yield gwc and gammon percentags.

> Few suggestions:
> 1. Have a tool bar button to set up a new position.  Same button would
> work for money game or match. IMO this is the biggest thing missing in
> GNU.

Yes yes yes, we know!!! It's on our TODO list, but we need to fix a
lot of other stuff before we can implement it. Please have patience!

> 3. When you put more than one checker on the you can get all of them off
> the bar except the last one. Is this a bug or I am just doing something
> wrong.

You should do the same as when you remove the last chequer from a
"normal" point, except that you should "slide" in the reverse
direction. For example, to remove the last chequer for player 1 from
the bar, you should hold the left mouse button down and move the
cursor upwards.

Scott Steiner  writes:

> Doesn't work for me. I've tried multiple times, but the checker is
> glued to the bar and won't move.

It's a little tricky but here's how to do it:

To remove the last checker from the bar for "player 0" you have to click
the checker with the right mouse button and hold the click, you then
move the mouse pointer upwards while still holding your click (as if
you're dragging basically); while you're dragging upwards you will see
actually that you are adding checkers but never mind that just keep
dragging; after you have a total of three checkers on the bar and you're
still dragging you will see that they suddenly all disappear.

To remove the last checker for "player 1" proceed similarly but use the
left mouse button and drag downwards.
Did you find the information in this article useful?          

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


GNU Backgammon

Analyzing GamesGrid matches  (Roy Passfield, Dec 2001) 
Batch analysis tool  (Øystein Johansen, June 2004)  [GammOnLine forum]
Cache size  (Ned Cross+, Mar 2004)  [GammOnLine forum]
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)  [GammOnLine forum]
Error rates: Gnu vs. Snowie  (Raccoon, Mar 2006)  [GammOnLine forum]
Even-ply/odd-ply effect  (Raccoon, Nov 2004) 
Even-ply/odd-ply effect  (Tom Keith+, Oct 2003) 
Even-ply/odd-ply effect  (Scott Steiner+, Dec 2002) 
Filter settings  (Robert-Jan Veldhuizen, Nov 2004)  [GammOnLine forum]
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)  [GammOnLine forum]
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)  [GammOnLine forum]
JSD's and confidence intervals  (Daniel Murphy+, Jan 2005) 
Logging rollouts  (Øystein Johansen, Oct 2004)  [GammOnLine forum]
Luck rate  (Kees van den Doel+, May 2002) 
MWC versus Equity (EMG)  (Ken+, Apr 2005)  [GammOnLine forum]
Manually entering first roll  (Andreas Graf+, Apr 2005) 
Match equity tables  (Raccoon, July 2005)  [GammOnLine forum]
Personal reflections  (Louis Nardy Pillards, Sept 2002) 
Playing two computers against each other  (Stanley E. Richards+, Mar 2008)  [GammOnLine forum]
Python scripting  (Øystein Johansen+, Nov 2004) 
Quasi-random dice in rollouts  (Ian Shaw, Mar 2004)  [GammOnLine forum]
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)  [GammOnLine forum]
Restarting a rollout with different settings  (Robert-Jan Veldhuizen, Apr 2004)  [GammOnLine forum]
Rollout settings  (geoff arnold+, Apr 2007) 
Rollout settings  (Stick+, Nov 2005)  [GammOnLine forum]
Rollout settings  (Robert-Jan Veldhuizen, Mar 2004)  [GammOnLine forum]
Rollout settings  (Ian Dunstan, Aug 2003)  [GammOnLine forum]
Rollout settings for the impatient  (Robert-Jan Veldhuizen, June 2004)  [GammOnLine forum]
Running rollouts in background  (Bruce+, Apr 2004)  [GammOnLine forum]
Saving rollout results from command-line interface  (Jeremy Bagai+, Apr 2006)  [GammOnLine forum]
Saving rollouts  (Mislav Radica+, May 2006)  [GammOnLine forum]
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)  [GammOnLine forum]
What's GNU?  (Gary Wong, Oct 2001) 
Which player is player 0?  (Neil Kazaross+, Oct 2004)  [GammOnLine forum]

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