Author: Christophe Theron
Date: 03:14:29 06/15/00
Go up one level in this thread
On June 14, 2000 at 16:52:43, Tom Kerrigan wrote:
>On June 14, 2000 at 16:17:25, Christophe Theron wrote:
>
>>On June 14, 2000 at 15:01:32, Dann Corbit wrote:
>>
>>>On June 14, 2000 at 06:56:27, Christophe Theron wrote:
>>>>On June 14, 2000 at 05:32:16, Alessandro Damiani wrote:
>>>>>On June 13, 2000 at 23:18:54, Christophe Theron wrote:
>>>>>>On June 13, 2000 at 16:53:39, Eugene Nalimov wrote:
>>>>>>>Combine two approaches -- 0x88 and 10x12. Use 12x16 board, and access board by
>>>>>>> board[0x20+square]
>>>>>>>(In C/C++ you can define macro for that).
>>>>>>>
>>>>>>>Than in each case you can use more appropriate of 2 methods.
>>>>>>
>>>>>>
>>>>>>Well actually Eugene it is what I do already. Sorry, I should have stated this
>>>>>>more clearly in my post. I don't use 12x12 or 10x12. I use 16x16 (actually I
>>>>>>just need 16x12).
>>>>>>
>>>>>>I don't even need to add 0x20... That's why I think 16x12 is more efficient than
>>>>>>0x88, and this comes from close examination of what a typical chess program does
>>>>>>most of the time.
>>>>>>
>>>>>>
>>>>>> Christophe
>>>>>
>>>>>The next step are bitboards.
>>>>>
>>>>>Alessandro
>>>>
>>>>
>>>>How many of the top programs actually use bitboards?
>>>
>>>My guess is that of those programs which are for sale, none of them do.
>>>The reason I guess this, is that the programs have been under development for a
>>>long time. They probably started out with one of the representations before
>>>bitboards. To change over to bitboards would require some tangible benefit.
>>>Since for 32 bit processors, the change is negligible, I strongly suspect that
>>>none of the professional programs have done this.
>>>
>>>However, once the 64 bit processors become mainstream, I expect all of them to
>>>make the transition at some point.
>>
>>
>>Don't be so sure. For example in my program I see no part that could be improved
>>with bitboards. I just don't need them.
>>
>>I really think that bitboards have no intrinsic objective advantage. That's just
>>another way of representing things.
>>
>>It is elegant and COULD be used to simplify complex operations, but the key
>>point is that in a chess program these complex operations are simply not
>>required...
>>
>>You can give me whatever example of an operation elegantly handled with
>>bitboards, but if your example is realistic and is really used in a chess
>>program I'm sure I can do the same thing with my data representation with no
>>additional cost.
>>
>>I have heard examples of ways of evaluating passed pawns that were alledgedly
>>faster with bitboards, but I do these evaluations in my program without
>>bitboards, and without pain...
>
>Out of curiosity, how do you test for passed pawns?
>
>-Tom
All things related to pawn structure is easily and quickly handled in a
dedicated hash table (nothing new here).
I store plenty of informations in this table, and that makes evaluation of
passed pawns quite easy, at a negligible cost.
Christophe
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