Author: leonid
Date: 06:34:35 12/18/99
Go up one level in this thread
On December 18, 1999 at 05:58:54, Tom Kerrigan wrote: >Generating pseudolegal moves is always better than generating legal moves. With >alpha-beta pruning, it is likely that you don't have to search all the moves of >a position. If you only generate pseudolegal moves, then you only have to test >move legality for the moves you search, and not all of the moves. > >If you don't have fancy logic to sort captures, then you should probably search >all of them first. Some might not be very good, but (again because of alpha-beta >pruning) you won't even have to search them in most positions, so it's not a big >performance hit. > >The best easy way to order captures is MVV/LVA. That means capturing the Most >Valuable Victim with the Least Valuable Attacker. So let's say you have three >possible captures: NxR, BxQ, PxQ. With MVV/LVA, you search PxQ, then BxQ, then >NxR. > >Another way you will hear people talk about is SEE, which stands for Static >Exchange Evaluator. This is a function that takes a square and finds all the >pieces that attack it and guesses at the outcome of an exchange. If a queen can >capture a pawn, but a pawn can take the queen immediately afterwards, a SEE will >tell you that's a bad capture. But if a queen can capture a pawn and nothing can >take the queen, the SEE will tell you it's a good capture. > >So a SEE is obviously better for move ordering. But it isn't very easy to >implement and it makes move ordering MUCH slower, so many people still use >MVV/LVA. > >-Tom Just want thank you for excellent explanation. Even if it was not intended for me, I found in it one valuable idea to try later. Thanks! Leonid. >On December 18, 1999 at 01:39:30, TEERAPONG TOVIRAT wrote: > >>Hi all, >>I notice that there are two methods in generating >>the piece moves. >>First is to generate pseudolegal moves from >>every pieces then check their legalities after >>making them. >>The second , more complicated code, only the >>legal moves are generated. >>In my opinion, the former method is good in the >>early phase of game because both kings are >>quite safe and far from attack so there should >>be only few illegal moves. But in the late middle >>game or endgame the kings are more exposed >>and usually take part in the game. There may be >>a lot of illegal squares for the kings. >>Is there a conclusion on this topic ?(for array board) >>Another question. >>Is it a consensus that all captured moves should >>be considered first ? I think those stupid sacrifice >>moves or some piece exchanging moves are not >>good enough to be above in the list. >> Do you agree? >> >>Thank for any help, >>Teerapong
This page took 0 seconds to execute
Last modified: Thu, 15 Apr 21 08:11:13 -0700
Current Computer Chess Club Forums at Talkchess. This site by Sean Mintz.