Author: Dave Gomboc
Date: 10:33:36 01/25/00
Go up one level in this thread
On January 24, 2000 at 16:10:20, Christophe Theron wrote: >However I'm wondering about the singular extension stuff. As I understand the >cost of detecting singular moves is linear (would not increase the branching >factor, just add a percentage to the total search time), but the cost of the >extension itself definitely increases the branching factor (increases the search >time exponentially). > >Of course I have no idea if it would be worse, in term of BF, than the set of >extensions microcomputers generally use. > >I think we can safely assume that their branching factor was above 5, and >probably significantly higher. And I did not even factor in the extra cost of >the parallel search. > > > >>I don't think it would do "worse and worse". Any more than any other program >>would. Although it might do worse as depth decreases depending on what they >>did in their eval. > > >With such a "high" branching factor, you can expect to end up doing worse in >term of average ply depth than a low BF program. > >Of course, with their NPS, they start with a huge advantage. But if you draw the >curve of ply depth versus time for both DB and a modern commercial program, you >can expect DB's curve to be eventually reached by the commercial's curve. > >That's what I meant by "doing worse and worse". I could have written "doing less >and less good". > >Maybe I'm wrong because the singular extension stuff would compensate for this, >and the pruning system of commercial program would lose important information >than a pure alphabeta search. But I don't think so. > > >My opinion is that Deep Blue is much stronger than micros just because it has a >huge NPS. > > >But if you present things like this, it's not very sexy. > >So Hsu decided to use a totally different approach than the micro's. > >By not using a good known pruning system and introducing a new extension scheme >of your own, you present yourself as being a pionner. A genius that is so bright >that he has understood that what everybody else is considering as very good >(null move or similar recipes) is in fact rubbish. A guru that has invented a >bright human-like extension: the singular extension! Singular (dual, ternary, etc.) extensions were created by observing a need. I'm sure there are things you've come up with (but not published, perhaps!) where you've found some aspect of your program lacking, set out to fix it, and found a way to do so. If you were an academic, at that point you would write up a paper about it. It has nothing to do with being a guru. It seems weird to me that when Ed Schroder says Rebel does better without null-move than with it, people believe it, but people criticize the DB team for not using it (e.g. from your text above: "by not using a good, known pruning system..."). Why is it such an impossibility for DB's selective search to not require it when some PC programs don't use it either? Dave
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