Author: Vincent Diepeveen
Date: 13:02:37 07/19/99
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On July 19, 1999 at 10:48:52, Robert Hyatt wrote: >On July 19, 1999 at 06:03:38, Vincent Diepeveen wrote: > >>On July 19, 1999 at 00:48:56, Robert Hyatt wrote: >> >>>On July 18, 1999 at 17:27:12, William Bryant wrote: >>> >>>>I have created a SEE routine for my program (following the general plan of >>>>Swap() >>>>from Crafty) and now have a question about where it should be implemented. >>>> >>>>I initially implemented it in the move generator. When generating captures, if >>>>the Captured_Piece - Capturing_Piece <0, I would uses a SEE score of < 0 to >>>>discard the move, never searching it. >>>> >>>>This created an overall speed up but leaves a number of questions. >>>> >>>>Some positions require a sacrifice to find the winning line. These positions >>>>are never found because the sacrifice move is always discarded and never >>>>searched. >>> >>> >>> >>>this is totally unsafe. In the full-width part of the search, you should be >>>able to look at these 'losers' at some point in the search, after the good >>>captures, killers, etc... In the q-search you can afford to ignore them since >>>the q-search is already full of errors anyway... >> >>i disagree here. You can very cheap do checks in qsearch and see these >>tricks 4 ply earlier. >> >>Let us list the programs that do some checks in qsearch, >>and the ones that do not a single one >> >>The programs from which i suspect (if u grow older you >>grow wiser) doing checks in qsearch (alfabetical listed): >>Diep >>Fritz >>Genius >>Hiarcs >>The King (chessmaster 4000 etc) >>Lambchop >>Nimzo >>Rebel >>Virtual Chess >>Zarkovx >> >>The programs from which is suspect not doing them: >>Crafty >>Ferret >>Junior >> >> >>He what a big coincidence, the programmers of the non-doing check in >>qsearch are more convinced about getting kicked silly by programs >>outsearching them. >> >>In fact crafty at 12 ply is in fact searching 8 ply >>tactical for some tricks which probably fall outside the >>horizon anyway, which is kind of weird. >> >>Ferret already gets a huge depth and has all kind of extensions >>seemingly; in a position where my DIEP searches 13 ply at the >>same hardware, both Ferret with way over half a million nodes got >>only 11 or 12 ply in paderborn in the middlegame against fritz >>fritz not doing better bye the way, as the paderborn version >>seemed having all kinds of extensions too, although fritz532 >>searches deeper in that position! >> >>Junior already gets like 17 ply anyway tactical (positional 8 ply), >>and with R=2 it's unlikely that you miss something tactical then, >>even though when talking about checks it sees obviously 4 ply less. >> >>But crafty. Oh crafty. Crafty does a very limited recapture extension. >>mate threats are extended very slightly, so that last helps a little, >>but further it simply sees tactical 4 ply less when we're talking >>about a check threat. >> > >My point is this. Your checks are good for some tactical shots. They are >awful for common positions. Because you are running down stuff in the q-search >that is totally wasted. And if you waste time here, you lose time elsewhere. What are you talking about, i don't do checks in common positions of course! I do only useful checks. >For every position you find where a check in the q-search helps, There are >hundreds of positions where it hurts just as much or more. If my game results NO doubt 1.e4,e5 2.Qg4,Nf6 Qxd7+ to name a bad check. Of course we wanna prevent bad checks. >were bad, I'd be looking at why. But I do just fine at present. I have older >versions of Crafty that _did_ do checks in the q-search (trivial to implement) >but they don't play better because of it, IMHO. Well hopefully you don't try all capturing moves either in qsearch, is kind of wasting nodes too: d4,d5 e4,dxe4 qh5 qxd4 qxh7 qxb2 qxh8 qxa1 qxg8 qxb1 etc. >If you want to solve tactical problems, it is probably a good idea to do them. >If you want to win _games_ I am not so sure. IE when you use my quad p6/200, >you are about 1/2 as fast as my quad xeon, yet when we play I don't see any >tactical oversights by my program, generally... And the extra depth on the >positional moves I get helps significantly when there are no king-chasing >tactics... > > > > >>Of course when getting 12-13 ply, chance is not big you miss tactics >>anyway. >> >>>> >>>>Is this the tradeoff of this heuristic? >>>> >>>>Is there a better way to apply the SEE rather than to all capture moves as they >>>>are generated? >>>> >>>>Are there other heuristics that allow these discarded moves to be found in the >>>>right positions? >>>> >>>>Here is an example position: >>>>1rr3k1/4ppb1/2q1bnp1/1p2B1Q1/6P1/2p2P2/2P1B2R/2K4R w - - >>>>It is from a list of mating positions posted by Dan >>>> >>>>I can find the winning mate in 0:32 without the SEE, >>>>and never with the SEE. >>>> >>>>Thanks in advance. >>>> >>>>William >>>>wbryant@ix.netcom.com
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