Author: Severi Salminen
Date: 14:19:32 01/08/01
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>>>i see you have 'futile moves' also. If you throw futility pruning out, >>>then nullmove should work brilliant positionally spoken. >> >>I tried, but the behaviour was the same. But then I removed my very stupid >>3-fold repetition algorithm (it is only adding different bitboards of a position >>to get a "key") and I got results with no fail highs or lows. I must find >>another way to find repetitions... > >aha perhaps there is the bug then! Actually no. Forget what I said above. The first modification was that I returned 0 if a position was reached 2 times instead of 3. This was the case when search results were different. Then I removed the whole sh#t and I got this odd failhig/low phenomenon again. The reason is nullmove (and nothing else) and at least according to Bob this kind of behaviour is unavoidable so I don't worry it again. The funny thing is that with the "2" version my engine found the desired a5! very quickly but without repetitions it insists on Kb3... >do you store repetitions in hashtable? No. I just generated this "hashkey" (it didn't probably work) and stored it to an array every time I entered a new position. Associated with this key was a counter and when it reached 3 I returned 0. I don't have hashtables implemented yet so that is the next thing to do. And with hash the repetitions should be easier to include. BTW should one count 2-fold repetitions instead of 3-fold? With 2 you would get the same result and prune more nodes? >simplest solution is to never give a cutoff from hash if >it is score 0.00, that's what i do and it always worked. Sounds reasonable. 0.00 means (or should mean) draw after all :) Severi
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