Author: Uri Blass
Date: 16:07:30 07/02/02
Go up one level in this thread
On July 02, 2002 at 17:47:27, Robert Hyatt wrote: >On July 02, 2002 at 16:06:56, Christophe Theron wrote: > >>On July 02, 2002 at 15:07:31, Robert Hyatt wrote: >> >>>On July 01, 2002 at 17:34:00, Alessandro Damiani wrote: >>> >>>>On June 30, 2002 at 23:59:59, Christophe Theron wrote: >>>> >>>>>On June 30, 2002 at 12:28:32, Robert Hyatt wrote: >>>>> >>>>>>On June 29, 2002 at 14:18:53, Christophe Theron 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. >>>>>>> >>>>>>> >>>>>>> >>>>>>>And maybe he had no good reason to do it. >>>>>>> >>>>>>>As far as I know there are many amateur programmers here that have spent much >>>>>>>more time in trying and validating ideas (not even speaking of the commercial >>>>>>>programmers) than Hsu. >>>>>>> >>>>>>>I think Hsu and his team have done a great job in implementing a chess program >>>>>>>in a chip. >>>>>>> >>>>>>>However I think taking him and his team as a reference in chess programming is a >>>>>>>big mistake. >>>>>>> >>>>>>>As I have said, I think there are many chess programmers here who are much more >>>>>>>skilled than Hsu and his team in chess programming. >>>>>>> >>>>>>> >>>>>>> >>>>>>> Christophe >>>>>>> >>>>>>> >>>>>> >>>>>> >>>>>>Hmmm.. I would _never_ make that statement. Have you _ever_ talked with >>>>>>Hsu or Campbell? I suspect not because if you had, you would not think >>>>>>them quite that incapable. >>>>> >>>>> >>>>>I did not say that they are incapable. They have done things I will never be >>>>>able to do. >>>>> >>>>>However I have read their description of the Deep genealogy (the document >>>>>published last year and describing their creatures in details, in particular >>>>>their evaluation function and search algorithms). >>>>> >>>>>I think it's probably as good as or even better than having a talk with them, or >>>>>else what is the purpose of their publication? >>>>> >>>>>Their evaluation function is quite complete but far from impressive (nothing >>>>>that a good micro program doesn't do - at least nothing important). >>>>> >>>>>The job they have done on search is on the other hand poor in my opinion. >>>>> >>>>>Poor is an understatement. Given the money they have been given for the project, >>>>>the almost total lack of work on the search algorithms is a shame. >>>>> >>>>>If they knew as much as many amateur programmers nowadays, they would have >>>>>worked harder on the search. It is obvious that more work on this would have >>>>>given much, much better results. >>>>> >>>>>The problem is that they have started their project with the level of knowledge >>>>>about search algorithms that was up to date at the time of Chess 4.8. >>>>> >>>>>They have invested almost no work on search before starting to design the chips. >>>>>And since they have not invested much time on this either when they were working >>>>>on revisions of the chips, in the end they have got chips able to do the kind of >>>>>search that was great... back in the seventies. >>>>> >>>>>Their chips do a brute force search, with a few exotic (most probably >>>>>inefficient) extensions. >>>>> >>>>>Since nearly twenty years we know that brute search is vastly inferior to a good >>>>>selective search. >>>>> >>>>>They have done a great achievement with a technique that is known to be vastly >>>>>inferior. >>>>> >>>>>That leaves a bitter taste of what could have been achieved with the same >>>>>resources if they only had somebody capable enough (read: averagely skilled by >>>>>CCC's standards) on the subject of chess tree searching in their team. >>>>> >>> >>>I _still_ have a problem reading that last paragraph. I wonder if Christophe >>>knows exactly who Murray Campbell is? IE he wrote the _first_ difinitive paper >>>on null-move search. He conned me into being the _first_ person to implement >>>what is now known as "PVS search" (null-window) at the 1978 ACM event (more >>>on this if you want to hear an interesting story). Singular extensions. a >>>2200+ chess player. I can't imagine _anybody_ saying "if they only had >>>someone capable enough, averagely skilled by CCC standards, etc" if they >>>actually _know_ Murray... >>> >>>Murray is anything _but_ "averagely skilled by CCC standards..." >>> >>>Anything but... >>> >>>And then there is Hsu, Hoane, Thomas, Andrew, etc... >> >> >> >>Then let's say they had forgotten about null move, if you really want to find an >>excuse for them. >> >>Or that they did not have enough time to implement it? > >Read the paper you mentioned. They _did_ use null move in places, just >not like we use it. They used it for threat extensions at least, and >perhaps in other ways if you read that paper carefully... > >Singular Extensions seems to be a popular topic. Vincent claimed it did >not work. Could not work. Now he depends heavily on them. I ignore vincent about it but I believe that deeper blue did not use singular extensions in a productive way. They are used in Ferret but not in the same way that deeper blue used them. Uri
This page took 0 seconds to execute
Last modified: Thu, 15 Apr 21 08:11:13 -0700
Current Computer Chess Club Forums at Talkchess. This site by Sean Mintz.