Author: Roberto Nerici
Date: 05:02:25 12/01/03
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On December 01, 2003 at 05:03:24, Daniel Clausen wrote: >On December 01, 2003 at 03:23:06, Roberto Nerici wrote: > >>Apologies for the off topic post :-) > >:) > > >>I'm implementing some basic time handling code at the moment. I've found a few >>bits on how to decide how long to think, some in threads here, some in some >>books I've got. Something I haven't seen is how/whether to modify the allocated >>time based on the number of moves available to choose from. >> >>It's obvious that if you only have one valid move you can make you just make >>that move instantly. I've got my engine to handle that. However, what if there >>are two moves to choose between? In a mid-game position where perhaps there is a >>check involved, there might be only two available moves and one is much better >>than the other. Does anybody's engine try to handle such a situation as a >>special case? I've got my engine to compare the scores of the two moves and if >>at the first check time (the point when my engine decides if it's searched >>enough or should carry on) there is a large difference, it picks the higher >>scoring move. However, I wonder if this is too risky, and of course there is the >>question of how "large" the "large difference" should be. > >Well, one thing you could try is this: if your opponent just captured a piece, >it's likely that you have to recapture (or capture something else) or you're >just down material-wise. So you could reduce the allocated time by factor X and >calculate normally. (which reduces your normal search depth a few plies) If >after the allocated time, the recapture is really the best move and you didn't >get a drastic fall in the score (e.g you're still in the [-0.2, +0.2] range of >compared to the previous search or something) it's probably ok to do the >recapture. Thanks, this is the sort of idea I was looking for. Are you suggesting that in the limited move case, you look for the type of move, and then do a relatively quick search just to check that it seems ok? Of course there will be positions where there is something counter-intuitive just over the horizon, but that it always going to be the risk. All I have thought of so far is to modify the allowed drop off in score between iterations, based on the number of moves available. i.e. if the engine normally decides to search longer if score for depth I is X or more below the score for depth (I-1), then for cases where there are only two moves available, make X a bigger value. Does that make sense? >>PS: you can all now get back to long, tedious hardware threads, attacking the >>ICGA, etc :-) > >Since you're a member of the ICGA, your input to this subject would be very >welcome though! :) Well, I just get the journal, I don't know anything that everybody in CCC doesn't know, and I don't want to set another bit thread going on the subject either! I suppose if I have to add anything, it would be that there are a group of people who get involved in these events (meaning, people who have competed at a WCCC or WMCCC in the last few years) and there are those who don't (for many, often good, reasons) and I think there is a big difference in opinion between the two groups. >Sargon (not a member of the ICGA because their payment system is a tad too >archaic for my taste) Sending a cheque off in this day and age is a bit archaic. Roberto/.
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