Author: Andrew Platt
Date: 04:53:37 09/22/04
Actually, more accurately a problem with null move and a position that appeared in this week's Washington Post Chess column: [D] 3K4/8/2ppp3/2pkp3/2ppp3/8/4P3/3Q4 w - - 0 1 The main thing to do is to wait for black to commit suicide, something that null moves are very bad at doing! The solution is to make an active waiting move that will position the Queen directly later: 1. Qa1 d3 2. Qc3 e3 3. exd3 cxd3 4.Qxd3# However, Schola does not want to get this mate. I can run it as long as I like and it still goes for the longer mate: 1. Kd7 d3 2. e3 c3 3. Qb3+ c4 4. Qb4 c2 5. Qxd6# If I disable null move it finds this very quickly. I suspect that there's a bug in the search somewhere though I can't find it and the traces look sane. The main problem is that the null move for Qa1 always cuts off so it retains Kd7 which is the first move it considers. Has anyone else had problems with positions like these and null moves? BTW, I have verified null move implemented but that doesn't help either. That does make a small difference if I jump the position to 1. Qa1: It then finds the fastest mate which the regular null move still doesn't do. I've also disabled some other things like the hash table which sometimes get in the way for me but that didn't change anything. Andy.
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