Computer Chess Club Archives




Subject: Re: Intelligent software, please

Author: Ed Schröder

Date: 02:15:55 11/26/01

Go up one level in this thread

On November 26, 2001 at 04:08:27, Otello Gnaramori wrote:

>On November 26, 2001 at 03:48:30, Ed Schröder wrote:
>>I have no idea Victor is talking about, Claudio has written some very
>>interesting topics about computer chess, see:
>I think that the following is the article mentioned by Victor :
>Infact it is written at a certain point :
>According to Ed's announcement in this web page, several programmers are facing
>the task of suppressing important amounts of programming code in the evaluation
>function, to achieve more speed and conquer their computer competitors by the
>brute force of tactical calculation.

That is a complex subject. At the time (about 2 years ago) I have written a
page about the issue to explain a bit. The topic was called "Chess in 2010"
and its contents are found on:

The page is still worthwhile reading but in the meantime my thoughts about
this have a bit evolved. That is that you really can throw out unnecessary
chess knowledge with the emphasis on "unnecessary".

Some specific chess knowledge through the years become out-dated due to the
speed of nowadays computers. An example: In the early days of computer chess,
say the period 1985-1989 I as hardware had a 6502 running at 5 Mhz. Rebel at
that time could only search 5-7 plies on tournament time control. Such a low
depth guarantees you one thing: horizon effects all over, thus losing the

To escape from the horizon effect all kind of tricks were invented, chess
knowledge about dangerous pins, knight forks, double attacks, overloading
of pieces and reward those aspects in eval. Complicated and processor time
consuming software it was (15-20% less performance) but it did the trick
escaping from the horizon effect in a reasonable way.

Today we run chess program on 1500 Mhz machines and instead of the 5-7 plies
Rebel now gets 13-15 plies in the middle game and the horizon effect which
was a major problem at 5 Mhz slowly was fading away.

So I wondered, what if I throw that complicated "anti-horizon" code out of
Rebel, is it still needed? So I tried and found out that Rebel played as
good with the "anti-horizon" code as without the code. In other words, the
net gain was a "free" speed gain of 15-20%, thus an improvement.

One aspect of chess programming is that your program is in a constant state
of change due to the state of art of nowadays available hardware. I am sure
a Rebel at 10 Ghz several parts of Rebel need a face-lift to get the maximum
out of the new speed monster.

One recent example: Century 4 eval is more speculative than previous versions.
Why? Because I believe (confirmed by my test results) that the program can
handle it because of the mixture of smart search and fast hardware. A deep
search simply filters out most of the "too speculative errors" of eval and
the net result is a better, even more attractive chess engine.


This page took 0.03 seconds to execute

Last modified: Thu, 07 Jul 11 08:48:38 -0700

Current Computer Chess Club Forums at Talkchess. This site by Sean Mintz.