Author: Robert Hyatt
Date: 10:55:42 11/26/02
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On November 26, 2002 at 12:40:03, Bo Persson wrote: >On November 26, 2002 at 00:36:39, Russell Reagan wrote: > >>On November 25, 2002 at 21:28:32, Robert Hyatt wrote: >> >>>The concept of a "captures only" q-search is so flawed that tossing out a >>>few extra captures, or keeping a few unnecessary captures is basically >>>unimportant... There are so many positions where a capture is not the best >>>move that to hope for much from the q-search is mostly wishful thinking... >> >>Exactly. Let's remember, q-search stands for "quiescence search", which means >>"searching for a quite or peaceful position." So we're looking for a position >>that is peaceful and unlikely to change drastically so we can evaluate it more >>accurately. > >Or rather evaluate it at all! > >Naturally, you cannot trust your material evaluation in the middle of a capture >sequence. :-) > >So, you have to play it out, or find a position where one side will pass. *Then* >you can evaluate the material balance. > >Forking the queen is something you should do in the regular search. Extend on >"forking potential" or something, and stay out of the qsearch! > >>Most of the "violent" captures (captures that will change the >>score of the position drastically) are bad ones anyway, so as Bob says, a >>capture only q-search has some pretty big holes in it. > >Yes, but... > >The idea is to figure out if the captures *are* bad. > >> >>Instead of thinking "generate captures", think "generate forcing moves". >>Captures, checks, some attacks...whatever forces the opponent or yourself to >>have to do something (or suffer the consequences). > >But "generate captures" is easy, and will find a lot of moves that are known to >change the evaluation drastically. These you *have* to try. > >The real killer might be a "silent" pawn move that opens up a diagonal for a >piece that blocks the opponent king's only escape route... > >Don't look for that in the qsearch! > > >Bo Person >bop2@telia.com The other terrible case is a pin. Rather than simply capturing a piece that is defended once (a simple exchange) I might first pin the piece which brings a second attacker to bear and I may win it outright. I've seen this from time to time... The pin comes to light when the first few moves are played out, you are committed, and _then_ you notice that he has something better than a capture that was suggested as best by the q-search.
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