Author: Heiner Marxen
Date: 15:54:42 05/31/00
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On May 31, 2000 at 17:38:52, Robert Hyatt wrote: >On May 31, 2000 at 17:25:22, blass uri wrote: > >>On May 31, 2000 at 17:21:05, blass uri wrote: >><snipped> >>>If people want to get an estimate how much better they can improve the move >>>ordering then I suggest to develop 2 programs. >>> >>>1)Program A searches with the same extensions of the original program when only >>>the order of moves may be different because it gets it from program B >>> >>>2)program B searches for the best move ordering and gives program A only the >>>knowledge about the order of moves to search. >>> >>>When you count nodes count only nodes of program A to get a fixed depth and >>>compare it with the number of nodes of the original program to get the same >>>depth. >>> >> >>I can add that I think that this is not a simple task to write the programs A >>and B(when the main problem should be writing program B that searches for the >>smallest tree to produce a cutoff). >> >>Uri > > >There are two issues: > >(1) you can write code to prove that one move is better than another, simply >by searching both moves. > >(2) you can _not_ write code to choose a move that leads to the smallest sub- >tree, without first searching the moves. Otherwise there is no way to compare >them. And once you have searched them, there would be no benefit to then >searching the move with the smallest tree _again_. > >This is one of those "you can't answer the question until you do the search, and >once you have done the search, it is too late to ask the question." It can be done where iterative deepening is done: you measure the number of nodes searched for the moves, and when searching with increased depth, after the first move you order the others in increasing node number from the last depth. I vaguely remember that this has been discussed here and is already done. If so, has anyone ever measured the effect (speed up) of such sorting? Heiner
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