Author: Severi Salminen
Date: 12:01:35 01/06/02
Go up one level in this thread
>Well...to begin with, "a movegenerator that allways generated the best move" is >clearly an unrealizable pipe dream. With such a generator, there is no reason to >search. You would generate the best move and then play it straight away. Yep, that's what I meant. [snip...] >The moral of the story is: The move you want to *play* should be the *best*, but >the moves you want to *analyze* are the ones that cost you the least amount of >work overall most of the time. > >Don't confuse the properties you desire in the moves you *play* with the >properties you desire in the moves you *analyze*. They are not the same. The best move (as seen from engine's point of view) allways results the least amount of work. Assuming that I also search the best reply to it and so on. This is a property of AB and is allways true. There is no point in searching 2nd best move first, ever. (see below) >Another example: Let's say you are at an analysis node and you have 2 moves in >mind to consider. Move #1 2X as likely to be best, but will require analyzing a >sub-tree that is probably 3X bigger than move #2. Which do you analyze first? >Just because a move is more likely to be best does not mean it is more efficient >to examine it first. >Bob came up with a good explanation that is more concise than mine: >http://www.icdchess.com/forums/1/message.shtml?205659 Bob is right but he not talking about the exact same issue here. Fail lows and fail highs are special cases. If we are in FH node, where every move causes a FH, any move will result this FH equally fast if we try the best moves first. And in some cases even faster (resulting a transposition node, or something). But generally it is best to search the best move first. And most of the time you simply can't know how big a sub-tree of a move will be. Well, I trust my move sorting algorithm anyway :) Severi
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