Author: David Dory
Date: 04:08:59 01/24/02
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On January 24, 2002 at 04:47:30, guy haworth wrote: >Would welcome sources of information on how chess-engines budget their time. > >Are the heuristics out there more 'conservative' than human players? What >criteria are used for departing from some norm-budget/move, assuming there is >one? Time management is always critical for chess programs. Iterative deepening is a term used to describe the process most used to integrate time management into the search of the program. Basically, the program figures out the average time per move and uses that until near the end of the time control. It explores the moves to the first ply (a move by one side), and checks how the time is now doing, periodically. It should still have plenty at this point, so it saves it's best move found so far, and goes to the next ply down in the search tree, and repeats, again saving it's data for best move at this depth. This is repeated until the time used is about 75% or so of the average time per move which it has figured out. If it has found a good move (and that definition varies from program to program), at that point it will then play it. If it hasn't, rather than play a bad move, the program will keep going deeper into the search, again, saving it's info as it goes (just in case the operator presses the key telling it to "MOVE NOW!"). When 100% of the average time per move has been reached, the program will play it's best move unless it knows it's still a bad move (bad might be defined as a move which lowers it's score by more than half a pawn). Again, the program spends more time searching for a good move, but at some point, say 150% - 200% of that average time per move, it will make the best move it has found, regardless. This is all based on the idea that some moves (such as book moves), and simple recaptures will use almost no time, while other positions need far more time to search before a good move can be found. > >Do chess engines modify their: > > a) opening books, > b) search and/or evaluation methods > >according to the time regime for the game? Not any program of mine! :-) >Are chess-engines able to handle the increasing variety of time-regimes being >defined now? Yes, using iterative deepening, time management is not the "*&^%/!!" (insert favorite cuss words here) problem it used to be. At the end of time controls it get's a little tricky. >What time-regimes are there and is there an established notation >for defining them? I would call it time regimens or time controls, but not "time-regimes". Why not log onto the chess servers and see? (Game in 'n' minutes, 'n' moves in 'n' minutes (primary), plus 'n' moves in 'n' minutes thereafter (secondary), and Fisher come to mind.) Dave
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