Author: Pete R.
Date: 15:51:40 08/05/99
Go up one level in this thread
On August 05, 1999 at 13:14:13, José de Jesús García Ruvalcaba wrote: >On August 04, 1999 at 19:03:25, Pete R. wrote: > >>On August 04, 1999 at 14:57:02, José de Jesús García Ruvalcaba wrote: >> >>>On August 03, 1999 at 21:29:14, Pete R. wrote: >>> >>>>Currently in the Kasparov vs. The World correspondence game there are a number >>>>of endgames that involve races between passed pawns on either side of the board. >>>>While the programs have been quite useful so far, they aren't too swift in the >>>>transition to the endgame when passed pawns are the issue. Where a human player >>>>would push his passed pawn at every opportunity, the programs tend to diddle >>>>around moving pieces, until the pawn is almost promoted, when they suddenly >>>>realize that one side is winning. For example in the following position, >>>> >>>>8/1p1kp2Q/2np4/1p2bpB1/8/3q3P/5PP1/5RK1 w - - >>>> >>>>I ran Fritz 5.32, Hiarcs 7.32, and Crafty 16.12 for many hours, enough to get to >>>>18 ply for Fritz and Crafty. All of them recommend the move g4 for white >>>>(Crafty switches to g4 at 15+ ply), which gets buried by b4!. For example, >>>> >>>>27. g4 b4 >>>>28. Qxf5 Qxf5 >>>>29. gxf5 b3 >>>>30. Rb1 b2 >>>>31. Kf1 Na5 >>>> >>>>and by now they will realize that white is losing. There are a number of >>>>possible endgames coming up involving a race between white's passed h pawn and >>>>black's passed b pawn, and the programs have a real hard time with it. What's >>>>going on here? >>> >>> I recommend to use crafty 16.15 with 'extension pushpp 1.0' for this and >>>similar positions, it will extend more aggresively on passed pawn advances (the >>>default is 0.75), and will see the dangers at shallowers depths. >>> I can not do it myself because I do not have "many" hours of computer time >>>available. >>>José. >> >>Thanks, I'll play with these new parameters. I think the ppscale might be the >>one to use vs. the extension, but I'll have to fiddle with it. > > Yes, increasing 'evaluation ppscale' can also help. Values over 200 are not >recommended (the default is 100). I love these features of crafty. Actually I couldn't get the extension command to work. I put it in the rc file, and no matter what syntax I tried I got an error - unrecognized parameter message.
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