Author: Robert Hyatt
Date: 20:51:48 12/08/01
Go up one level in this thread
On December 08, 2001 at 14:41:23, William Bryant wrote: >On December 07, 2001 at 23:52:37, Robert Hyatt wrote: > >>On December 07, 2001 at 18:13:18, William Bryant wrote: >> >>> >>>>I was seeing an error 400K-500K nodes, on my PIII/750 laptop, which is about >>>>one error every 2 to 4 seconds. On my quad (I didn't run the test there as it >>>>was playing on ICC) this would turn into an error every second or less, which >>>>is not acceptable. Some positions produced _many_ errors per second, when there >>>>were fewer pieces so that more pawn moves were being searched... >>> >>>I believe the thread was discussing the frequency of errors using a 32 pawn hash >>>key which in previous threads you said that, after testing, produced no >>>significant degree of collisions or errors. >> >> >>This was a mistake on my part. My testing (no errors) was actually done several >>times, but prior to my conversion to 32 bit signatures for pawn hashing. When I >>tested this at David's urging, the number of collisions was ridiculous... I am >>now using 64 bits again. >> >> >> >> >>> >>>If I read the above correctly, this implies that it does produce an unacceptable >>>level of errors? >>> >>>Or is this above error rate discussing the main hash table using a 32 bit key? >>> >> >>pawns only. as explained above. >> >> >> >>>Would you please clarify. >>>Thank you. >>> >>>William > >OK, If the pawn hash table also hash to be indexed off of 64 bit zobrist >numbers, >but this is a completely separate table than the main hash table, then can a >portion of the zobrist numbers used to create the main hash key be reused for >creating the pawn hash key? > >example: > >instead of -- > >UInt64 ZTable[2][6][64]; //the integers for the main table >UInt64 PZTable[2][64]; //the integers for the pawn table > //using an additional 1K of memory (or catch) > >use-- > >UInt64 ZTable[2][6][64]; //the integers for the main table >UInt64* PZTable = ZTable; //and reuse the numbers to save in catch > >Would this create problems? > >William It is late, and I may have misunderstood what you asked, but for me, I use the _same_ random numbers to update the normal (full) hash signature, _and_ the pawn hash signature.
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