Author: Stuart Cracraft
Date: 07:51:13 07/31/04
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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
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