Author: Uri Blass
Date: 09:25:55 07/31/04
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On July 31, 2004 at 10:51:13, Stuart Cracraft wrote: >On July 29, 2004 at 01:37:36, Volker Böhm wrote: > >>Hi, >> >>what do you "extend" in quiescese, only "check-evades" (king is in check - all >>evades are done, not only captures) or checking moves (move that set king in >>check) too? >> >>What extends do you have you in total in normal search? (Make sure, that you >>NEVER add extensions to add more than one depth at one position). >> >>"Usual" Extend Algorithm for main search: >> >>DoMove(Position, Move) >>if (InCheck(Position)) Extend = 1; else Extend = 0; >>// Usually limit extensions to the double of RootDepth (Depth value at root) >>if (Ply + Depth + Extend > RootDepth * 2) Extend = 0; >>PosVal = -Search(Position, -Beta, -Alpha, Depth - 1 + Extend, !Wtm); >>UndoMove(Position, Move); >> >>Do you use the same algorithm? >> >>Greetings Volker > >GA only extends on check in quiescence. If upon entry to the quiescence, >the program is in check, it returns a value equal to the result of >a regular main-search of 1 ply in this position. No limits. > >If I remove this, the program's performance drops. > >Any attempt by me to add a check extension to the main search does not >work. The program's performance suffers unless the check extension is >limited and when limited, the performance does not go up but stays the >same. > >So I have kept check in quiescence only. > >It is possible that a separate set of features will work well in >a game but not in problem sets. The features I have noticed drop >problem set performance for me include > > FUTILITY > RECAPTURE > CHECK EXTENSION in main search > ...etc. > >I have kept all these as conditional compilation flags so that the >can be resurrected for regular games. > >They do NOT help with problem sets. In my case. > >Stuart I guess that something must be wrong with your program because check extensions everywhere usually help in test suites(movei use check extensions in most cases and it often search more than 1 ply after check if the number of possible replies is small). Uri
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