Author: Robert Hyatt
Date: 17:20:37 07/02/02
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On July 02, 2002 at 18:54:49, Keith Evans wrote: > >Sorry to be anal retentive, but that's a bit of a stretch. Here's what they say: > >"The chess chips optionally support the use of an external FPGA (Field >Programmable Gate Array) to provide access to an external transposition table, >more complicated search control, and additional terms for the evaluation >function. In theory this mechanism would have allowed the hardware search to >approach the efficiency and complexity of the software search. Null move search >was also explicitly supported by this method. Due to time constraints, this >capability was never used in Deep Blue." > Read on. On page 67, section 4.1, item 3, "mate threat". "It is relatively simple using a null move search to detect if there is a threat in the current position.... The Deep Blue implementation ... Which matches what I said. They had support for a normal null-move search had they wanted to use it, but they did use null-move to detect threats, something that has been done before (and several of us use a form of mate threat extension based on this idea presently). So they used null-move in at least one way, without using it as a forward pruning algorithm, which fits with Hsu's "no errors in the search" theme he mentioned repeatedly over the years. Extra extensions were one thing to him, but outright errors were something else not to be tolerated. Right or wrong. I obviously disagree about the errors in a normal null-move search, but I can hardly argue with their success... >As a verification guy my motto is - "If it's untested, then assume it's broken." > If I had been regarded highly enough to review this paper before publication, >then I would have crossed out this paragraph. > Wouldn't disagree there.
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