Author: Volker Böhm
Date: 03:59:15 01/15/04
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On January 14, 2004 at 15:44:56, Matthias Gemuh wrote: > > >Does it make sense to use PVS algorithm to implement QSearch ? >It does not seem to help my engine. > >/Matthias. PVS is good if 1. there are many alternative nodes (never got good results in my connect-4 game with 7 moves max. at one ply) 2. the move ordering is good 3. you can narrow the window greatly compared with the usually arising position-values in a search. In QSearch: 1. Depends a little bit what nodes you are searching. If you only search "good" hits selected by SEE its verry narrow. If you are searching check-moves too it´s wider. You can consider PVS if searching check-moves tool. 2. Move ordering in QSearch is seldom good. You haven´t got a PV and seldom usefull hash-moves. If you turn off SEE for "good hit-moves" the ordering is too bad for PVS 3. I´am staring a new search with a windows of -30cp .. +30cp around the search result of iteration-1. The window in QSearch is often of witdh 0, but verry seldom of width > 60cp (only if I´ve got fail-high or fail-low against the initial window). The results of a QSearch differ greatly as they are hitting material. The least effective hit move gets +100cp. Conclusion: the window is allready verry narrow compared to the results of QSearch calls. Conclusion: Don´t use PVS in QSearch. Greetings Mangar
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