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Subject: Re: bitboard question

Author: James Robertson

Date: 07:53:54 01/13/99

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On January 12, 1999 at 23:48:46, Robert Hyatt wrote:

>On January 12, 1999 at 11:34:19, John Coffey wrote:
>
>>On January 12, 1999 at 11:10:21, KyoJin Kim wrote:
>>
>>>How much will it be faster using bitboard than without using bitboard?
>>>
>>>Thanks.
>>
>>
>>Speed is a hard concept to talk about.  I am no expert, but bitboards might
>>have more over-head while at the same time they simplify evaluation of the
>>position, which may save you time in evaluating.   Although I don't fully
>>understand it, I am told the bitboards can also help in move ordering by
>>looking at captures first, and the improved move ordering reduces the number
>>of positions looked at.
>>
>>My idea of a chess algorithm was not to use bitboards because they do not
>>provide me with all the information that I want.  Instead I was going to
>>keep track of a great deal of information each time a piece moved - this
>>approach might be slow but might also help my evalution, move ordering, and
>>pruning.  I can't say that it will work, because it might be months before I
>>can put these ideas into practice.  But I have started on the user interface.
>>
>>John Coffey
>
>
>A couple of things.  Until we get full 64 bit architectures (or until we run
>on Digital alphas, MIPS R10000's and HP PA8000's) on PC machines, bitboards are
>at the very best, a break-even proposition.

What!? All that work to only program a break-even proposition??

There is extra overhead involved,
>until we get to 64 bit machines...  But once we get there, I don't see any
>disadvantage at all, and the information 'density' really favors 64 bit apps
>when running on a 64 bit machine.
>
>as far as 'didn't provide you with all the information you want' that might
>be the result of not working with them long enough.  I haven't found a single
>question I can't answer with bitboards... and many times the question is easier
>to answer with them than without...  particularly in evaluation where I spend
>a bunch of time...

if a program spends a lot of time in eval() is the difference in speed made up?

James



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