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Re: [Bug-gnubg] Dice Rolls

From: M B
Subject: Re: [Bug-gnubg] Dice Rolls
Date: Fri, 16 Aug 2013 22:48:07 -0500


I have respect for ALL backgammon players globally no matter what their level. 
GNU when set at a high level of play is basically the premier teacher of BG 
IMHO. For instance, or as an example, when GNU is set at a high level and a GNU 
move us seen as an error (even though we can look at the stats) we do not 
complain. We assume an advantage when in actuality the GNU move is the best 
"strategical" move given the situation based on statistics of the game (which 
we may not know since we are not computers calculating gazillions of games). 
That is not to say GNU is "looking into the future." As far as I know there are 
no algorithms looking into the future. They all, to my knowledge, are looking 
at the past to set themselves up from the first roll of the dice to the last. 
Strategically anything can happen. Hence the reason when GNU is behind it will 
not give up until long after s human player would. It knows the past and what 
is "possible". It does NOT know what will happen.


Backgammon is about setup, placement, location on the board, combinations, the 
likelihood of combinations, knowing to block those combinations if possible 
while moving forward strategically, blocking out, bearing off, everything, 
every move matters. GNU when set at a high level simply does not make the same 
emotional moves humans make.

GNU is not beating you or itself by way of the dice. Its just that good. Why 
else would so many people be here?


On Aug 16, 2013, at 22:00, "JD" <address@hidden> wrote:

On 08/16/2013 07:56 PM, Michael Petch wrote:
> On 16/08/2013 7:35 PM, JD wrote:
>> Played5 games (me vs gnu-bg).
>> Of course, I played the best I know how for both
>> myself and gnu-bg.
>> I only won 1 game.
>> Sounds funny doesn't it?
>> I played BG against myself and I lost!!
>> Well,the fact of the matter is that I was
>> astounded by the amazing dice rolls for gnu-bg
>> when I had the advantage on the board. Gnu-bg
>> got itself oout of multiple jams by dice rolls favorable
>> to itself.
>> Because of what was clear to me as a preferential
>> dice rolls for gnu-bgin all 5 games, I decided that
>> the dice areskewed in favor of gnu-bg.
>> Best way to test it is to have actually equally matched
>> individuals play 10 or even 100 games (or of course,
>> some might say thousands or millions of games) of Human vs Human,
>> always making note of the dice rolls for gnu-bg.
>> As of right now, I am not impressed with the designers of the dice
>> roll algorithm.
> The default dice roll algorithm is actually based on Mersenne Twister.
> The source code is available and to date (After 15 years) no one has
> found the code that gives preferential treatment to the bot unless you
> set that option. GNUBG supports a number of alternative dice generation
> algorithms including manual dice (you can roll them with your own dice
> and enter manually). There is also dice generated from www.random.org
> which provides randomness through real world entropy (and isn't based on
> a pseudo random number generator. That can be set via
> Settings/Options/Dice . If you want the bot to give itself better rolls
> (or yourself) there is a mode for that. No one has found code that makes
> the bot look ahead to future rolls to make its decisions.
> The neural net plays at a world class level and is better (IMHO) than a
> significant majority of the players in the world. Many players also
> overestimate their own skill and don't easily accept that the bots play
> significantly better. The better someone plays the more lucky they may
> appear.
> I also did a statistical study (I'll see if I can dig it up) of 100
> million rolls and 10's of thousands of matches the bot played against
> itself. The results were that the rolls produced were indistinguishable
> from what you'd get with properly thrown precision dice in the real world.
> If GNUBG outplays a particular human consistently then my guess would be
> that the bot is better than that human.
Hello Michael,
While you can do a statistical study of the randomness of
dice rolls, it does not take into account that the engine can
see current board, and determine that it (the gnubg pseudo-player,
which is also me  - since I selected human against human, and
player 0's default name is gnubg). I find it very strange that
in 4 out of 5 games, where I was playing both as player 0 and player 1,
with player 0 being gnubg, the rolls for gnubg were incredibly
winner rolls - totally amazing to me.
So, I was not playing against the bot, as you say. I was playing
human against human, and I did not enable the "Dice Manupulation"
option at all.
But I can tell you in all honesty that I was doing my best for each roll
of the dice for both players (0, and 1).

At any rate, I do not have the skill to discern how the engine might
do what I observed, even if I peruse the source code.



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