Author: Robert Hyatt
Date: 09:52:10 03/16/00
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On March 16, 2000 at 10:59:46, Georg v. Zimmermann wrote: >On March 16, 2000 at 10:45:39, Robert Hyatt wrote: > >>On March 16, 2000 at 09:42:43, William H Rogers wrote: >> >>>I am still having a problem with quiesce. Lets assume that after several plys >>>my program ends up on e4. Do I just look at e4 to see if there are any captures, >>>or do I search the whole board for captures etc.? >>>I know that checks are included here too. >>>Thanks in advance >>>Bill >> >> >>Some do it either way. I look at the whole board, find all the captures, >>then weed out the ones that seem futile to search... > >Another question on that: > >Doesn't quiesce and extending on captures reach the same goal to a certain >extend? What technique is better at what ? Do you do both ? > >Thanks. In look at the 'search' as being broken into three unique and distinct components: (1) the basic search. Here we look at _everything_ without discarding any moves at all. We extend when we think the position warrants it (in check, recaptures, etc.) IE we try to discover all the cute tactical stuff in this part of the search, since what we find is pretty much error-free (except for insufficient depth of course.) (2) the qsearch. Here we only want to make sure that there are no _simple_ combinations that win or lose material. I don't personally want my q-search to find wild tactical things, because it is _so_ error-prone when you mainly search only captures. IE often the best response to a capture is not a capture, but some other move with an even stronger threat. Since the q-search is so error-prone, I try to limit what it sees, which limits these errors. (3) the evaluation. Which is basically blind to dynamic tactics. Since it doesn't understand threat sequences and so forth, we try to make sure that we don't give it such positions to evaluate, by letting the normal search and the q-search carry us to a reasonably quiet position where the eval is correct. (3) is where almost _all_ programs make their mistakes. The eval says "white is ahead by a piece, plus positional compensation" but it doesn't understand that "black mates in 7 moves if we reach this position."
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