Author: Keith Evans
Date: 14:04:01 06/29/02
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On June 29, 2002 at 16:18:16, Uri Blass wrote: >On June 28, 2002 at 17:54:56, Keith Evans wrote: > >>On June 28, 2002 at 16:33:10, Scott Gasch wrote: >> >>>Another idea that I read from was that generating non-capturing checks in the >>>qsearch against a side that has had a chance to stand pat already is a waste. I >>>really don't understand this idea and disagree with it. Imagine black has had >>>an oppertunity to stand pat but instead plays RxN (N appears hung). Well this >>>looks really good unless white then generates Qd4+ forking blacks R and K and >>>winning the R. If you neglect to generate checks on a side who has already had >>>the chance to stand pat you let him get away with RxN and like it. If the only >>>reason to add checks to the qsearch is to find mates then I agree -- checking >>>after a side could stand pat is wasted. But if the goal is to improve tactical >>>play then I think this idea is not sound. >> >>I'll be very interested to see what responses this generates. Hsu took the time >>to design and implement special logic to help generate checking and check >>evasion moves in Deep Blue which I assume was used in qsearch. This was not a >>trivial undertaking - it adds both additional logic and additional interconnect. >>He probably had a good reason for doing it, since he could have used that time >>for something else like implementing a small hash table. > >How do you know what hsu did and what he could do? > >I do not know and I do not assume that people do the best things that they could >do. > >I believe that there are ideas that can do programs 50 elo better with little >work and they are not used by programmers only for the simple fact that the >programmers did not think about them or did not evaluate them correctly. > >Uri My point wasn't to say that Hsu made the best decisions possible - I'm actually curious to see a justification for the added complexity. I would assume that he did a careful analysis before commiting, and am definitely interested in all arguments pro and con. Maybe he was right, or maybe all of that time was wasted. I don't understand your question about knowing what Hsu did? His move generator is pretty well documented. Unfortunately the thought processes behind the decision to add additional capabilities (checking, check evasion,...) when going from Deep Thought to Deep Blue are not well documented. (I'm talking strictly about the movegen not about eval here.) That's why I'm so interested to see the responses. I barely have an opinion on the matter, other than that I am interested in building a minimalistic move generator in hardware, and obviously don't like unnecessary complexity. Regards, Keith
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