Author: Christophe Theron
Date: 20:46:38 04/09/04
Go up one level in this thread
On April 09, 2004 at 16:27:51, Uri Blass wrote:
>On April 09, 2004 at 15:26:34, Christophe Theron wrote:
>
>>On April 09, 2004 at 14:27:48, Sune Fischer wrote:
>>
>>>
>>>>Clearly, nothing beats the ugliness of bitboards.
>>>
>>>This may not be the best example to judge by.
>>>
>>>-S.
>>>> Christophe
>>
>>
>>
>>In the contrary, I think it's fairly typical of bitboard code.
>>
>>Elegance is supposed to be the strong point of bitboards.
>>
>>The only thing I find elegant is the pseudo-great starting idea "64 squares <->
>>64 bits".
>>
>>Passed this point everything becomes unreadable and ugly.
>>
>>I also see it often used to pre-compute attack tables and such, which is in my
>>opinion contrary to one of the most important things I have learned in computer
>>chess: do not compute anything in advance if you are not certain that you will
>>use it.
>
>Chest the best mate solver is using attack tables.
>
>
>
> This is not an intrinsic problem of bitboards, it's just that use of
>>bitboards often go along with this misuse of computing resources, is it just by
>>chance?
>
>Movei is not based on bitboards but I use attacktables for my legal move
>generator and my makemove update the tables.
>
>I today almost do not use attack tables for the evaluation but I think that they
>can be used.
>
>For example if you may want to know the pieces that are attacked by both side
>both for better order of moves and better evaluation.
>
>I think that attack tables may help you to detect faster pieces that are
>attacked.
>
>>
>>Bitboards are a great tool allowing you to compute very complex things in a
>>blink. The problem is that in a chess program you rarely need to do these
>>complex computations if you know what you are doing, and so you end up with ugly
>>and unreadable code and waste of resources (in particular of L1 and L2 caches).
>>
>>That being said, I do not want to be too harsh: it is probably possible to write
>>a top-level chess program using bitboards, a program that would be not very far
>>behind the programs using more portable approaches like 0x88 and derivatives.
>>
>>Somebody will write one some day.
>
>I believe that everything is possible here because chess programs are simply
>weak(not relative to humans but relative to what they can become).
>
>The main problem is that no good mathematicians who are also good programmers
>decided to go for the task seriously.
>
>I think that all the linear stuff of doing something that you do not need is
>relatively unimportant to the improvement that you can get by better search
>algorithms and even if we assume that bitboards are 3 times slower than not
>using bitboard being 3 time slower is simply unimportant relative to better
>search algorithms.
>
>I believe that I have the right ideas how to do it but right ideas are not
>enough and translating them to a code is not easy.
>
>Uri
So basically bitboards or not bitboards is not the important question. So I
prefer to have code simpler to read and not to mess with ((b&(b-1))|~b).
Christophe
This page took 0 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.