Author: Tord Romstad
Date: 03:17:57 07/25/03
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On July 24, 2003 at 14:52:34, Matthias Gemuh wrote: >On July 24, 2003 at 10:35:46, Tord Romstad wrote: > >>>> >>> >>>BigLion ? no checks in QSearch(). >> >>OK, this confirms my suspicion that checks in qsearch have a great influence >>on the solution time at this position. >> >>Have you tried searching checks in qsearch? It is worth a try, IMHO. It >>seems that different people have very different experiences with this, but my >>program plays much worse in the middle game when I remove the checks. In >>the endgame it is less clear; I am currently experimenting with this. >> >>Tord > > > >BigLion is very slow, so checks in QSearch() almost halt the engine :). Gothmog is also not among the fastest. It does around 150-200KNps on a Pentium 4 2.4GHz. I am not sure checks in QSearch is necessarily a bad idea in slow engines. Many of the old, slow dedicated chess computers in the late 80s and early 90s had checks in QSearch(), I think. Checks in QSearch() do not have to be very expensive, if you put severe restrictions on what checks you include. This is how I do it: In the QSearch(), I first generate and search all non-losing capture moves. If none of the capturing moves resulted in a cutoff, I generate and search non-capturing checks if both of the following are true: 1. We are at the first ply in QSearch(), or all previous moves in QSearch() for the side to move have been checks and all moves from the opponent have been single-reply-to-checks. 2. alpha < KNIGHT_VALUE. At least in my program, this works very well and is not particularly expensive. But as BigLion is apparently slightly stronger than Gothmog at the moment, I am probably not the best person to give you advice. :-) By the way, what is the difference between BigLion and Taktix? I have read your web page, but cannot find any explanation ... Tord
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