Author: Gian-Carlo Pascutto
Date: 08:26:13 12/11/00
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On December 11, 2000 at 09:55:34, Rémi Coulom wrote: >I am not sure I understand all you wrote, but I see a small problem in using >-value+1 instead of -value: it should not change anything in practice if you >are using a hash table. I do not use a hash table. I am using a stripped-down search that does not do nullmove or any kind of pruning either. Just PVS. My program does have all those features, but I've killed them out in order to fix problems with basic functionality, like e.g. best line display. I've got it working to the point where I can use aspiration search and PVS without losing any PV's. I'm now running into the problem that I get fail-low's after failing high on the same score, if I enable nullmove and hashtables. I know this is possible if you use forward pruning and pondering together, but I'm not pondering. Also, it still happens if I disable the usage of the scores and bounds from the hashtable, and only use the suggested best move. I do not understand why I am getting this behaviour (different scores) if I only change move ordering. >I do not know of an easy way to get the full PV all the time. Maybe those who >use MTD(f) have thought about it. I think that if there is a way, then it must >use the hash table because of the problem I have mentionned above. I do not >know how, though. This does not look like an easy problem. Crafty, EXChess, ... seem to always get the full PV. If I use the above trick I do too, but I cannot use the bound from the hash to tighten the window or I lose it again. -- GCP
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