Author: Carlos del Cacho
Date: 16:00:30 01/27/01
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On January 27, 2001 at 16:43:05, Tony Werten wrote: >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 ) Yes. I don't include checks in quiesce. I rely in check extensions in normal search. And my evaluation function can only get positional values over 2 pawns in the endgame so I should disable this there. Carlos > >Tony > >> >>Greets, >>Carlos
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