Author: Tony Werten
Date: 13:43:05 01/27/01
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On January 27, 2001 at 16:34:53, Carlos del Cacho wrote: >On January 27, 2001 at 14:30:18, Severi Salminen wrote: > >>Hi! >> >>I made a few test games between a version of my engine using SEE and another >>using just MVV sorting. I played only a few (24) games and time control was >>5min/G and in 8 games 1min/G. The result was 12-12! Is this possible, normal, or >>do I have a bug? I would have guessed that the SEE version had beat the hell out >>of the other but that never happened. It seems that SEE slows things down a lot >>and the net result seems to be that it searches equally deep compared to the >>other version. Has anyone here measured the true benefit of using SEE? Could you >>show me positions in which SEE makes a big difference or could you run self-test >>games between two versions of your program? Are there positions where SEE hurts >>searching? I really like to know if SEE is worth it? I have a relatively slow >>computer (300Mhz Celeron, Crafty running at 80KNPS) so could time control and >>overall speed have influence on this? >> >>Any comments are welcome! >> >>Severi > >Just a quick test. Two runs on WAC 5 sec/problem: > > - SEE pruning in Quiescent Search: 270 > - without it: 246 > >So it is definitely a win for my program (Pepito). > >The only difference between these builds was commenting out these lines: > > val = SEE(pos_stack->jug); > if (val < 0) > continue; > > val += MARGEN_QUIES + pos_eval; > > if (val <= alpha) > continue; > >But you should note that I try not to call the SEE function whenever possible. >If I can get a cut with pos_eval + mat_gain I give up this capture. Another >question is if SEE is profitable in normal search. I also it there but kicking >it out would be a bit more difficult so I haven't tried yet :-). At the same >time captures are generated I assign them their MVV/LVA scores. Then I try >captures with positive scores and when this gets below zero I call SEE for >remaining moves. Losing ones are searched after all non captures. I'm not really >sure about the gains here so I'll give it a try... I'm a correct in assuming you don't do checks in qsearch and your MAX_EVAL < 2 pawns ? Because in that case SEE is definitly a win ( maybe also if you do some checks and max_eval is a bit bigger than 2 pawns ) Tony > >Greets, >Carlos
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