Author: Tord Romstad
Date: 14:14:26 03/24/04
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On March 24, 2004 at 16:52:04, Dieter Buerssner wrote: >On March 24, 2004 at 16:44:12, Tord Romstad wrote: > >>>How do you handle extensions? Currently, most of my extensions are >>>set after the engine moves and since the extensions affect the draft >>>(which in turn affects the validity of the hash match) it seems like this is >>>a problem. This might be workable (in my current scheme) if I started >>>tracking the extensions that were triggered by a move in the hash >>>table. >> >>You are right, this is a problem. My "solution" is to ignore the problem >>and hope it isn't too important in practice. > >By, "I ignore the problem", you mean, that you just probe the HT in the ETC code >with depth - 1 (as if there would have been no extensions/pruning triggered by >that move)? Yes, exactly. >Did you compare in tactical test suites ETC on and off? Yes, but the last time was at least half a year ago. It's probably time to test it again. >Are there cases, where ETC on needs one depth more, to solve a tactical >problem, than ETC off? I would guess, that this could be the case now and >then. I am 100% sure it happens now and then, and I'm also 100% sure that the opposite thing happens. One of the things I consider when making pruning and reduction decisions is the history of the move. Moves which have very rarely failed high in the past are more likely to be pruned or reduced. Of course, it will happen many places in the tree that one particular move at one particular node is pruned with ETC disabled and not pruned with ETC enabled, because the history count of the move will be different in the two cases. Even tiny changes in my move ordering often results in a tactical problem being solved one ply earlier or later. If I want to retain a tiny hope of keeping my sanity, there are only two ways to go: Ignoring this kind of problem, or rewrite my search from scratch. >If it is the case >few times (not totally rare), this might soon outweigh the smaller trees you >cited (10%). > >Are you trying ETC after hash probing and before null move? No, after both. Tord
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