Author: Marc van Hal
Date: 16:21:13 05/10/02
Go up one level in this thread
On May 09, 2002 at 20:29:37, Robert Hyatt wrote: >On May 09, 2002 at 18:08:52, J. Wesley Cleveland wrote: > >>On May 09, 2002 at 13:22:01, Robert Hyatt wrote: >> >>>On May 09, 2002 at 12:43:08, Robert Hyatt wrote: >>> >>>>On May 08, 2002 at 16:22:16, J. Wesley Cleveland wrote: >>>> >>>>>In this position which is an obvious draw for any decent human player, >>>>>[D]8/8/p2b4/8/p7/3k4/1B6/1K6 w - - 0 4 >>>>>crafty is clueless - static evaluation is -3.19, evaluation after 34 ply is >>>>>still -3.19. >>>> >>>> >>>>This is a harder case that my current "knowledge" doesn't cover. Black >>>>has the right bishop for its rook pawns. Of course white has the same >>>>colored bishop and if they are traded, it is a draw because of simple >>>>rook pawns left with the opposing king controlling the queening square. >>>> >>>>I can fix this cheaply and will. But it is simply a good illustration of >>>>just how many special cases there are in endgames that computers have to >>>>handle... >>>> >>>>Be interesting to see if any program currently has this evaluation knowledge >>>>to call this a draw, statically. It is doable. >>> >>> >>>Old version: >>> >>>material evaluation................. -2.00 >>>development......................... 0.00 >>>pawn evaluation..................... -0.24 >>>passed pawn evaluation.............. 0.00 >>>passed pawn race evaluation......... 0.00 >>>king safety evaluation.............. 0.00 >>>interactive piece evaluation........ -0.92 >>>total evaluation.................... -3.16 >>> >>> >>>new version: >>> >>>material evaluation................. -2.00 >>>development......................... 0.00 >>>pawn evaluation..................... -0.24 >>>passed pawn evaluation.............. 0.00 >>>passed pawn race evaluation......... 0.00 >>>king safety evaluation.............. 0.00 >>>interactive piece evaluation........ 2.24 >>>total evaluation.................... 0.00 >>> >>>Fix was straightforward to do without hurting performance... Just had to >>>"explain" to it that the right bishop is no good if the opponent has one >>>too... >> >>You need to be carefule here - this position is won for black. >>[D]8/8/p2b1B2/8/8/pk6/8/1K6 w - - 0 1 > > >I had this one covered already. King must have access to a2 in this position >for it to kick in the 'drawn' scoring code... Otherwise it was too messy as >the pawn and king are too close... It also was the march of the black king wich did do the trick in the game. But it was not a bug in Crafty because schredder5.32 made the same mistake. Regards Marc
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