Author: Robert Hyatt
Date: 08:33:31 08/28/03
Go up one level in this thread
On August 28, 2003 at 11:09:19, scott farrell wrote: >On August 28, 2003 at 10:55:20, Mridul Muralidharan wrote: > >>Hi, >> >>I use qsearch as a method of reaching quiet and calm positions, not as a method >>to eliminate all captures. >>Hence , I also try stuff like forking moves , threatening and checking moves , >>etc - these may not be captures or promotions - but normal moves that can be >>very threatening and dangerous. > >ONE VOTE FOR STAND QUIET FROM Mridul. > >I just score the pins/skewers etc in the eval, and it mostly throws out the >position using alpha/beta instead. YMMV. > >I remember my engine before stand pat. It thought if there was a capture on the >board it had to take it, and go through with the sequence. It played very funny >chess for some time, and still managed to win lots, and played very very >aggresively, making huge recapturing combinations on the board - very amusing. >So if you dont put stand pat, how do you tell it that it doesnt have to take one >of the moves in the move list, it can make no move instead (which when the full >width search gets there, it can make a non capture move). How can you not have a stand pat option? Else you are _forced_ to play the only capture, QxP, even though the pawn is defended. The error rate there is much higher than the error rate in classifying a position as "quiet" when it is not. If there are no good captures left, you at least know it is "somewhat quiet" even if there might be a violent non-capture threat left. > >> >>Of late I have been noticing that , standpat though it give a nice speedup , can >>be very bad for my search - atleast the quality of output it produces. >>Even though I dont allow standpat in case like when in check , etc I still see >>the pv ending in positions where , due to standpat , I get the score of a lousy >>position. Maybe need to tune up eval more ?!! > >I am interested to hear this, maybe I will try to remove, and other ideas >instead of stand pat. Don't tune up the eval. Tune up the search so you don't give your eval such positions to handle... > >> >>The observations you made w.r.t passed pawn was also observed by me - maybe like >>you said , I need to identify more patterns for passed pawn eval. But the fact >>remains , you cannot find all of them. So maybe it makes sense to keep these in >>qsearch ? >> >>Extensions have always only blown up the search tree for me - skewed up search >>tree , where a whole bunch of useless checking moves or captures keep getting >>extended , while worthwhile lines miss out due to that one extra ply search that > >>they need to prove they are the best moves. So I rarely extend now , even >>checking moves are rarely extended , unless they are "good". > >Every time I touch my check extensions, the strength goes down. I now just leave >them at extend 1 full ply when in check, and 1 full ply for single escaping >move. I am interested in how you discern 'useless checking' from good checking >moves though? > >> Recaptures - almost >>never (depending on which version :) ) , have not tried singular extensions - >>because I have not understood the implementation related concepts that well , >>nor have I found much of a documentation of how it could be implemented. > >I put recaptures in/out/in/out also, but have them in now, found someone's idea >somwhere, only recap on the same square, and only winning captures. This seemed >really really strong. > >My extensions do go crazy sometimes. In the end game of blitz, sometimes I see >it only gets 4 ply full width, and 25 ply in extensions, but it trounces the >opposing computer with excellent pawn pushes and checks - and wins most of the >time only searching 4-5 full width plies. > >>I tried a search through ccc archives - way too many threads - but none of them >>had something that would not have adverse effects on search - tried a few ideas >>and miserably failed. > >tried this also, blew up the search too much. > >>Rest of the extensions - i threw them out of the window. >> >>My $.02 >> >>Regards >>Mridul
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