Author: Randall Shane
Date: 09:36:09 10/21/05
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On October 21, 2005 at 11:36:38, chandler yergin wrote: > >There are no Bugs in any Engine! >The Engine does nothing. >The Algorithm does everything! > >http://www.seanet.com/~brucemo/topics/minmax.htm > <Bruce Moreland's text elided for conciseness's sake> > >To say there is a Bug in the Engine is just not correct! >To say that the Algorithm is biased.. does not work for some positions >is not correct. >If it did, it would not work for any position, and would be disfunctional. Hmm. Might as well take a shot at this. Chandler, there are numerous errors in your statement above. 1) Bruce's text was a basic outline of a class of algorithms based around the minimax principle, not an algorithm itself. It was intended as a basic description for the beginner. It certainly wasn't meant as a detailed description of the internals of a wrold-class chess program. 2) When you say that "The Engine does nothing. The Algorithm does everything!", do you have any idea what that means? An algorithm is merely a description of a process, of how to do something. A chess engine is a particular implementation in CODE of an chess search algorithm In the computer world, algorithms -- especially loosely-described ones -- don't DO anything. CODE does stuff. The basic alphabeta algorithm is modified in most engines with quiescence searches, pruning, extensions, move ordering -- the possibilities are seemingly endless. The are a myriad of choices to make in the implementation of the search. Also, alpha-beta depends on an evaluation function at each node of the search tree -- and there are millions of choices to make in the design and implementation of the evaluation function. Some of those choices are demonstrably bad Furthermore, implementations of algorthms in CODE can have bugs -- and many of those bugs can be subtle. Bugs can be obvious like program crashes, or less obvious such as position misevaluation. Fritz appears to have a bug in some positions. Chessbase agrees, and reportedly has issued a patch. So, when you said that Fritz didn't have a bug, despite the evidence -- well, you were wrong. And using Shredder to prove your point, well, doesn't prove your point, and was irrelevant. If what you said was correct (and it isn't!) -- then wouldn't the top chess programs play identically? Fritz and Shredder are two different programs, written by different people, with different design decisions, different search choices, different evaluation functions, etc. It would be beyond shocking if they acted the same in all situations. In fact, if two programs in a complicated area such as chess produce identical output, that would be serious evidence that some sort of cheating (such a stealing code) was going on. As always, the devil is in the details, Chandler.
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