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An experimental draw recognizer function

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Robert Hyatt

Joined: 27 Feb 2006
Posts: 15816
Location: Birmingham, AL

Post subject: Re: An experimental draw recognizer function Posted: Thu Mar 15, 2012 2:10 pm

ethanara wrote:

Hi
When I was walking around, i got this idea for engines to better recognise whether or not a position is draw due to the 50 move rule. The idea is based on the fact that if you cant get a better position/win material et cetera within 50 moves, the game is a draw. Here it is in pseudo-code (in the search function):

Code:

if position_is_endgame && saved_before_flag == false then
first_eval_in_endgame = score
saved_before_flag = true
first_eval_in_endgame_depth = depth

and later in search, in a further depth

Code:

score = evaluate()
eval_difference = first_eval_in_endgame - score
if saved_before_flag == true && eval_difference > Table[depth_difference] then
return draw

So, it is basically saying that if you or your opponent don't improve your position with x centipawns in y depth, then it is quite surely a draw.
Table should be something like this:

Code:

Table[64] = "5, 7, 10, 13, 15, 17, 20" // and so on....

Of course, if you're over a special margin (1½ pawn or so), it will be completely dumb to do this.
The only problems remaining is having good values in table and a good endgame knowledge.
I will test this with doublecheck
Regards
Ethan

There are other approaches as well. In Crafty, once we start to approach the 50 move rule, I start to pull the score back toward zero. This makes any sort of move that produces progress to look better if it resets the 50 move counter.

There is a danger, of course. You can try so hard to avoid a draw, that you lose, if your eval is not really accurate.

Display posts from previous:

Subject	Author	Date/Time
An experimental draw recognizer function	ethan ara	Wed Mar 14, 2012 2:56 pm
Re: An experimental draw recognizer function	Lucas Braesch	Wed Mar 14, 2012 3:50 pm
Re: An experimental draw recognizer function	Robert Hyatt	Thu Mar 15, 2012 2:10 pm
Re: An experimental draw recognizer function	Robert Hyatt	Sat Mar 17, 2012 4:14 pm
Re: An experimental draw recognizer function	Vincent Diepeveen	Sat Mar 17, 2012 1:30 pm
Re: An experimental draw recognizer function	ethan ara	Sat Mar 17, 2012 5:00 pm

TalkChess.com Forum Index -> Computer Chess Club: Programming and Technical Discussions

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