Computer Chess Club Archives


Search

Terms

Messages

Subject: Re: Why is Crafty so fast?

Author: Robert Hyatt

Date: 12:31:24 11/24/97

Go up one level in this thread


On November 24, 1997 at 14:59:47, Giovanni Lavorgna wrote:

>I recently came across two simple chess programs, TSCP (Kerrigan) and
>SCP (Stanback). These programs come with source code that can be
>compiled without much effort under Unix. They both play a fair game of
>chess, expecially considering their size. The only thing that puzzles me
>is that they look very slow when compared to a program like Crafty, even
>after switching its hash tables off. I tested this on a variety of
>positions and Crafty seems to consistently search at least 1-2 plies
>deeper. Compiler optimization switches I used were the same for all
>programs. I wonder what makes Crafty so much faster than the other two
>programs. Is this due to the use of bitboards?
>
>Also, is there available a basic-Crafty version that retains all its
>speed, without all the other features that have been more or less
>recently added. I mean, I like to see Crafty continually improved, but I
>would love also to have a easy-to understand version to fiddle with.
>
>Thanks in advance.
>
>Giovanni Lavorgna

I haven't seen Tom's program, so I can't begin to guess why Crafty is
faster.  There are two kinds of speed:  (1) NPS and (2) time to depth.
bitmaps help NPS when done right.  But, in reality, bitmaps and
non-bitmap
programs are fairly close in speed if both are done right.

So the difference comes down to move ordering, hashing, null-move,
search
extensions, and so forth...

There isn't a "easy-to-read" version of crafty, unfortunately.  As it
has
gotten better, it has gotten more complicated.  And harder to read as
well.
Best to start with something like Tom's program, understand that, then
take
what you learned to help you understand Crafty...




This page took 0.01 seconds to execute

Last modified: Thu, 15 Apr 21 08:11:13 -0700

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