Author: Will Singleton
Date: 19:39:53 11/10/99
Go up one level in this thread
On November 10, 1999 at 20:47:40, Robert Hyatt wrote: >On November 10, 1999 at 20:32:58, Will Singleton wrote: > >>r2r2k1/pp3ppp/2n2b2/4p3/2N5/1PP2B2/1P3PPP/R2R2K1 b - - >> >>This position gives my program fits. Some stronger progs solve it easily. It >>appears to be a simple case of extending on captures, and then doing the qsearch >>right, which I apparently am not. >> >>Here's the main line which should be found: >>Rxd1 Rxd1 Rd8 Rxd8 Nxd8 Nd6 b6 Nc8 Bg5 Nxa7 Bc1 and gets the pawn back. >> >>It appears that you need 13 ply to see that the bishop can get the pawn back. >>Extending on a capture that brings material back to nominal, there are 2 >>extensions in the above main line, so you now need 11 ply. The qsearch reduces >>this to 10. And that's what my program needs, 10 ply. Seems too long. >> >>I would love to find this sooner without blowing up the tree. >> >>(from a game on ICC today, Postmodernist vs Amateur) > > >There are two ways you have to look at such positions: (1) what is the right >move and why is it right? (b) what is the second-best move and why is it wrong? > >In this position, crafty isn't what I would call "happy". It plays Rxd1 after a >second or so on my xeon, at depth=7. But the score is roughly -.6 and it >doesn't get better even at depth=12... So it might be some sort of positional >mis-judgement you are fighting, rather than not seeing some tactic that looks >simple... Bob, My program has an eval similar to yours, but that's not what I was asking. Mine initially thinks black will lose the pawn (eval < 1) after Rxd1 Rxd1 Rd8 Rxd8, because it doesn't see the bishop going down to c1 to recover it. IOW, it doesn't want to play the initial RxR, which causes major problems. So it's a tactical problem for my program. Will
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