Author: leonid
Date: 13:31:38 10/03/99
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On October 03, 1999 at 15:07:58, Ed Schröder wrote: >>Posted by leonid on October 03, 1999 at 08:26:51: > >>I am not sure what you want to say with "extention" but my trying was very >>simple. The identical positions were tryed on Rebel and Hiacrs using same >>computer. Number of plys demanded were the same and from boths games it was >>asked to make search by "brute force". Rebel was incredebly speedy. How >>raw speed is implemented in final game it is the next question to ask. But >>potential of the game is on its raw speed anyway. >> >>To Rebel was said: >>1) Brute force - on. >>2) Hash table - put to zero. >> >>To Hiacrs was said: >>1) Selectivity - put to zero. >>2) Hash table - put to lowest value possible, to 1024k. >> >>So, it is true that Hiarcs did his search at brute force and he really a >>looser? Great mystery for me. >> >>Thanks to everybody who will make this enigma vanish! >>Leonid. > >The keyword to understand the topic = extensions. > >Chess programs do use all kind of extensions and all chess programs do >it another way. Some programs do not emphasize on extensions other >programs heavily use extensions. > >A common example of an extension is to extend the ply-depth with "1" in >case the king is in check. Thus instead of searching 6 ply the remaining >tree is searched for 7 plies. If there is another king-in-check case found >the search is extended to 8 plies and so on. > >So you see a 6-ply search isn't a 6-ply search as a lot of variations in the >tree are searched deeper. > >Some program will extend king-in-check cases even more. On some types >of checking moves Rebel will extend 2 plies. Other programs have their >own ways of doing things. The end result is that you can't compare programs >based on ply-depth. > >Ed This explanation puzzle me. My impression was that "brute force" in given number of plys deep should include nothing but number of plys asked. Every other extra ply for every other extra reason is inappropriate. I can only understand that in all games logic should go some extra plys (or extention) if it like to do this but not when "brute force" is asked. To see some extra ply in "brute force" search (even partially) is pious fraud. It sound like find the mate in 5 moves but announce it as mate in four. Brute force search in certain number of plys signify for me search for all the possiblities that existe for given position but going only the number of plys said to be performed. If "brute force" is what I see it to be, it says more that every other aspect of the game about the general capability of the chess game itself. Leonid.
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