Author: Magoo
Date: 16:53:10 06/14/03
Go up one level in this thread
On June 14, 2003 at 17:24:56, Uri Blass wrote: >On June 14, 2003 at 17:11:11, JW de Kort wrote: > >>On June 14, 2003 at 10:30:58, Magoo wrote: >> >>>I did some tests last night, replacing my in_check() function with attack >>>tables, my thought was that it would be faster, but the result was not that >>>good, ok i did a fast hack, scanning the whole board because i dont have piece >>>lists, but my previous x-ray in_check function was huge. But now im wondering if >>>attack tables (implemented with piece lists) are that much better than x-ray. >>> >>>You have to check all pieces, = 8 pieces (king checks). >>>You have to check if pawns are promoted... = x pieces. >>>Check two squares in front of the king. >>> >>>And of course, sometimes you have to do some tracing.. (sliding pieces). >>>In the opening, middlegame there are usually pieces near the king, so the x-ray >>>based in_check only has to trace a few directions. >>>This got me thinking that the difference between the two isn't so big, am i >>>correct? maybe attacks are a few % faster? >> >>Hi, >> >>my in check is also a time consuming process. But is it absolutely necessery? >>Maybe it is possible not to check for check at all and just check if a capture >>removes the king one ply later. I have not tried this idea but maybe it is >>faster then using an in check. >> >>Also i'am thinking of implementing attack tables in my 0x88 program but i have >>not found a fast approach. Ant tips?> >> >>regards >> >>Jan Willem > >In most cases you can use the last move to verify >that the king is not in check. > >If the black king is at e8 and the last move of white >is a2-a3 then the king is not in check >because both a2 and a3 are not in queen direction or knight direction >from the king. > >It is only one example. > >I do not do it in that way because I have attack tables >for every square but if people are interested in something >simple to detect if the king is in check then using >the last move is the most simple idea. > >Uri Uri, what is the name of your program? where can i download it? How have you implemented in_check() with attack tables? and is it really that much faster than tracing? About using the last move, that is something very interesting, i will try it out!
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