Author: Dave Gomboc
Date: 22:46:04 05/15/98
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On May 15, 1998 at 16:53:14, Robert Hyatt wrote: >On May 15, 1998 at 10:40:52, Dave Gomboc wrote: > >>On May 14, 1998 at 08:57:46, Vincent Diepeveen wrote: >> >>>... could be true. This means [Fritz] simply has no knowledge about what >>>to exchange. This is also the big weak point of Rebel. >>> >>>Ed schroeder states here that he is relying on leaf evaluation. >>>In that case, rebel doesn't have code about what pieces to >>>exchange. >>> >>>Main point is that you may not evaluate the exchanges. You should >>>look to the material that you keep afterwards. So the resulting >>>position. >>> >>>I dunno why Rebel+Fritz+genius and some others >>>are so horrible in these exchanges, but my first guess was piece square >>>tables. Now i say: perhaps mobility is a reason too. >>>The common thing of all these programs compared to Crafty, Zarkov, Diep >>>and some others is that they lack mobility terms. >> >>Crafty only has mobility for bishops at this point. I think Ferret is >>not using a general mobility term either, if I recall correctly. The >>trend has been to move away from measuring mobility (well or badly), not >>toward it. >> >>Dave Gomboc > > > >Correct, but not for the reasons you'd suspect... IE it has nothing to >do with performance, since mobility costs practically nothing in my >code. >But, in most cases, particularly for the queens and rooks, mobility is a >"result of winning", not necessarily a "cause of winning." My very >first >eval in Crafty was 100% mobility. It didn't work well. Now, other >terms >replace mobility with more useful information, such as rooks on >open/half- >open files... this increases mobility, but is a measure of *useful* >mobility >rather than general mobility. The queen is a good example, that often >if >you move it to the square where it has the most mobility, that square is >"gross"... from a strategic point... > >For bishops, I haven't done much yet, which is still on my todo list, so >mobility is still used there. But for all the other pieces, I believe >there >are *better* positional terms than simple mobility... Actually, I expected what you said, :-) because you've said it in previous posts. Mobility seems to be one of those things that come up every three months or so. Dave Gomboc
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