Author: Gian-Carlo Pascutto
Date: 09:35:31 06/18/00
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On June 18, 2000 at 12:00:08, Ed Schröder wrote: >On June 18, 2000 at 10:36:40, Gian-Carlo Pascutto wrote: >> >>I find it interesting to notice that even Rebel has some trouble with this, >>taking more than 10 times as much time to resolve the 10th ply. > >That's pretty normal whith such big score differences (2.47 -> 11.74) as >search is confrontated with big score fluctuations which causes move >ordering to collapse. I wouldn't bother too much about it, it's quite >normal. It may be 'normal' for most chessprograms, that doesn't make it good. I'm specifically trying to get the search/time relation more stable in positions with lots of threats/extensions. I'd prefer the score to gradually increase over several plys than to have it search for 30 minutes and come up with the mate score. Some programs are very good at this, some totally botch it. I suspect Memory Enhanced testers (e.g. MTD(n,f)) are very good at this, but I heard they can give weird results due to extensions sometimes, and that's exactly the problem I'm fighting here ;) A little test with AnMon showed that indeed the fail-high is very gradual and constant over time, but it still has the blow-up effect when moving over to the next ply, and pretty badly even. (I suppose that is because of the moveordering failing) I'm trying to get an idea how to control this effect in an aspiration/PVS searcher. That's why I'm asking for as much data as possible, and the details of the search that are used. This is one of the best I've got so far: Analysis by Little Goliath 2000 v2.8: (edited) 19.Rg1 Nf6 20.Kb1 b6 21.Rgh1 h5 22.f4 µ (-1.00) depth: 8 00:00:02 414kN 19.Rxh5 µ (-0.89) depth: 8 00:00:03 414kN 19.Rxh5 gxh5 20.Rxh5 Kf8 21.Rxh7 Ke8 22.Qf5 Kd8 23.Qxf7 Kc7 24.Qxe7+ Kc8 ± (1.33) depth: 9 00:00:04 2184kN 19.Rxh5 gxh5 20.Rxh5 Kf8 21.Rxh7 Ke8 22.Qf5 Kd8 23.Qxf7 Kc7 24.Qxe7+ Kc8 25.Rh8# +- (2.43) depth: 9 00:00:07 2184kN Times 5, quite acceptable. 19.Rxh5 Qxa2 20.Rxh7 Qa1+ 21.Kc2 Qxh1 22.Rxh1 f5 23.e4 Re8 24.exf5 g5 25.Rg1 +- (9.80) depth: 10 00:00:36 3654kN 19.Rxh5 Qxa2 20.Rxh7 Qa1+ 21.Kc2 Qxh1 22.Rxh1 f5 23.e4 Re8 24.exf5 g5 25.Rg1 +- (9.80) depth: 11 00:00:37 19616kN For some reason it now fails low again ?!? 19.Rxh5 Kf8 20.Rxh7 Ke8 21.Qe4 Kd7 22.Rxf7 Re8 23.Rg1 Qxa2 24.Rxg6 +- (5.40) depth: 11 00:00:50 19616kN 19.Rxh5 Kf8 20.Rxh7 Ke8 21.Qe4 Kd7 22.Rxf7 Re8 23.Rg1 Qxa2 24.Rxg6 +- (5.40) depth: 12 00:00:55 30184kN Times 6, again not bad. 19.Rxh5 Kf8 20.Rxh7 Ke8 21.Qe4 Kd7 22.Rxf7 +- (#9) depth: 12 00:06:02 30184kN But now we get a fail-low again... 19.Rxh5 +- (#109) depth: 12 00:06:10 30184kN 19.Rxh5 Kf8 20.Rxh7 Ke8 21.Qe4 Kd7 22.Rxf7 +- (#9) depth: 12 00:06:10 30184kN This is the worst: Analysis by Amy 0.7: 19.Rxh5 = (0.00) depth: 8 00:00:01 83kN 19.Rxh5 gxh5 20.Rxh5 Kf8 21.Rxh7 e6 22.dxe6 fxe6 µ (-0.91) depth: 8 00:00:01 83kN 19.Rxh5 gxh5 20.Rxh5 Kf8 21.Rxh7 e6 22.dxe6 fxe6 23.Kb1 µ (-0.78) depth: 9 00:00:02 143kN 19.Rxh5 = (0.00) depth: 10 00:00:03 246kN 19.Rxh5 gxh5 20.Rxh5 Kf8 21.Rxh7 Ke8 22.Qf5 Kd8 23.Qxf7 Qxc4 24.Qxe7+ Kc8 ³ (-0.27) depth: 10 00:00:03 246kN 19.Rxh5 = (0.00) depth: 11 00:00:05 473kN 19.Rxh5 gxh5 20.Rxh5 Kf8 21.Rxh7 Ke8 22.Qf5 Kd8 23.Qxf7 Kc8 24.Qf8+ Kc7 ² (0.44) depth: 11 00:00:06 473kN 19.Rxh5 = (0.00) depth: 12 00:00:13 1089kN Times 25 ! This is nearly minimax. 19.Rxh5 gxh5 20.Rg1+ Kf8 21.Bg7+ Ke8 22.Bh6 +- (2.20) depth: 12 00:05:08 1089kN 19.Rxh5 = (0.00) depth: 13 00:06:01 19.Rxh5 gxh5 20.Rxh5 Kf8 21.Rxh7 e6 22.dxe6 Qxa2 23.Qxd6+ Kg8 24.Rxf7 Qa1+ 25.Kd2 Rd8 +- (1.95) depth: 13 00:06:12 19.Rxh5 = (0.00) depth: 14 00:08:48 After 14 plys there still is no sign of a decent score. Actually I think there may be a bug in Amy: notice it is failing low to exactly zero each time. The search results look very strange. -- GCP
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