Author: Robert Hyatt
Date: 10:17:49 10/29/99
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On October 29, 1999 at 04:08:13, Peter McKenzie wrote: >On October 29, 1999 at 03:08:55, David Blackman wrote: > >>On October 29, 1999 at 02:34:23, Ed Schröder wrote: >> >>>Your argument is in contradiction also. The MAIN improvement for nowadays >>>programs since 4-5 years comes from NULL-MOVE, right? This includes Crafty >>>as well. >> >>Bob was using null move in Cray Blitz a bit more than 5 years ago i think. >> >>> >>>And who gave you null-move? >>> >>>Right, 2 commercial chess programmers :-) >>> >> >>Commercial chess programmers did not invent null move. As far as i know the >>modern form of null move was invented by the Russian Caissa team (Donskoy, >>Alazarov, Adelson-Velskiy etc) in the early 1970s. These guys were not >>commercial. >> >>By the late 1970s several British programmers had heard about it and it was >>probably Don Beal (who is not commercial as far as i know) who made it well >>known, sometime in the 1980s. > >While it is true that the concept of the null move was around for a long time, >it took even longer for people to figure out what it was good for :-) > >I think Doninger was the first to publish about null move pruning. Previously, >null move had been mainly associated with threat detection and quiescence search >as far as I'm aware. Actually it was Chrilly's paper that talked about using the null-move search to detect threats. Don Beal used it as a simple selective approach, and wrote an engine that solved an amazing number of the WAC test positions on a simple Z80 microprocessor (I think Z80, I could be wrong as I am not at the office where the copy of the paper is). I used it as he suggested, exactly, except not in the q-search. This was probably presented in the 1985/6 time frame, but I am no longer certain. I wish I had kept the main.c type comments in Cray Blitz, as I have in Crafty from day 1. I started doing this in 1986 in Cray Blitz, and at that point, null-move was already in use (R=1 non-recursive as I said). So I can't be very precise about when I added it. But it was definitely added after seeing either a rough draft or formal paper from Beal. I've always attributed this to him.
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