Author: scott farrell
Date: 08:09:19 08/28/03
Go up one level in this thread
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). > >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. > >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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