Author: Chris Whittington
Date: 04:08:32 12/30/97
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On December 29, 1997 at 17:31:25, Robert Hyatt wrote: >On December 29, 1997 at 17:18:05, Chris Whittington wrote: > >> >>On December 29, 1997 at 15:07:36, Robert Hyatt wrote: >> >>>On December 29, 1997 at 14:37:53, Stuart Cracraft wrote: >>> >>>>On December 28, 1997 at 13:30:31, Robert Hyatt wrote: >>>> >>>>>On December 28, 1997 at 11:47:20, Stuart Cracraft wrote: >>>>> >>>>>>What is SEE? Some canned knowledge routine? >>>>> >>>>>Static Exchange Evaluator... a procedure that looks at all possible >>>>>captures on a specific square and returns a score based on the expected >>>>>gain (or loss) of initiating the first move of the exchange sequence... >>>>> >>>>>used to order captures for one thing... and to cull outrageously >>>>>losing captures for another... >>>> >>>>How much increase in quiescence-search (and overall search) efficiency >>>>does this provide? Or speedup for that matter. >>>> >>>>Is your SEE routine written in a way that it would be simple to >>>>rewrite/convert >>>>for another program? >>>> >>>>Which of the Crafty modules is it actually in? >>>> >>>>Thanks, >>>>Stuart >>> >>> >>>It is in swap.c... >>> >>>It can speed up the search by a factor of 2 or 3, assuming you aren't >>>doing anything "good" about ordering your capture search yet. If you >>>apply SEE to each capture, sort based on the score returned, the tree >>>will shrink. If you toss out captures (in the q-search) where SEE >>>returns a score < 0, you will get another big reduction... and if you >>>use the SEE score to defer losing captures until after winning captures, >>>hash move, even exchanges, history and killer moves, you will save even >>>more time... >> >>Just a thought: suppose *all* programs perform the capture search >>according to the theory: try all 'winning or equal' captures and cull >>the rest. >> >>Then you play all these programs against each other to produce an SSDF >>list. >> >>Would it be any surprise if the list measured this sub-game of chess >>performance? >> >>Multiply it up by all the other 'kludgey' things that chess programs all >>do, and what have we got ? >> >>Chris Whittington > >No idea. I do this because, as I have written many times, I *don't* >want >the quiescence search to find tactics. Because it is not qualified to >do >so. I only want it to evaluate the most elementary of tactics, the >capture >moves. I don't want it to consider checks, or find overloaded pieces, >or >anything like that, because I don't trust it to do so. IE if you >include >PxR, QxB, because the P was overloaded defending two pieces. But >suppose >you try that and follow it because it appears to win two pieces for a >rook, but after RxN, you discover your opponent casually plays Bb2 >pinning >that rook on your king and winning it outright. You won a knight, >dropped >a rook, and could end up losing. I don't know how to pick up that Bb2 >pinning >move in the q-search. And since I don't, I really would like to see my >q-search almost non-existant, because it is so inaccurate. But this >lets >the normal search depth reach a level that is quite good. Remember that >what you do at the tips is expensive, while what you do well inside the >tips is almost free... I'm trying to control "the work at the tips..." > >losing captures, you occasionally will pick up on an overloaded piece >(RxN, Er, this wasn't quite the point I was trying to make, sorry. Try again: if all programs do the same thing (ie cull bad captures in the q-search); and we then construct rating lists of these programs performance against each other; isn't it a bit like a rating list of fighting octupii with seven legs against each otherf ? Or, does it actually measure chess ? And, since many programs perform many other kludges of such type, isn't the result like octopii fighting with well less than their full complement of legs ? So, I seek to warn of the dangers of everybody operating to the same paradigm and then incestuously comparing their 'strengths'. Chris Whittington
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