Author: Robert Hyatt
Date: 21:29:00 01/25/00
Go up one level in this thread
On January 25, 2000 at 21:26:19, Christophe Theron wrote: >On January 25, 2000 at 13:33:36, Dave Gomboc wrote: > >>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. > > > >If you are an academic, you NEED to write a paper in order to be recognized as >such. > >You need to invent something different. > >Even if it is not as efficient as what has been published already. > >DB is a wonderful opportunity for such "new" things. With or without it, your >machine is going to be very successful because of the computing power you >managed to generate. Just add a new algorithm to it, make good publicity around >it, and you get credit for this new algorithm as well. > >By designing a chess chip, Hsu knows he will only be remembered as a bright >"technician". > >By designing a new algorithm and associating it with a success, he will be >remembered as a good theorician. Much better, isn't it? > >Well done from a PR point of view. Maybe I'm wrong, but this singular extension >stuff is so far really suspect to my eyes: Why spend so much time in a new >algorithm that has still to prove it is worth the effort, when you could have >boosted the power of your machine by merely using null move or something >related? > > I don't think SE has been found 'bad'. I used it in CB. Bruce is doing it. Dave Kittinger did it. Richard Lang did it (I think everyone but CB and HiTech implemented it in a less-expensive and less accurate way, but they all are getting results that are quite good, still, particularly Bruce with Ferret. > > >>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..."). > > > >If the DB team did not have enough time, they could simply take the null move >algorithm because there is documentation available on it. > >However null move is not the final say. Rebel does very well with ANOTHER >pruning system. Junior does very well with ANOTHER pruning system as well. And >there are other programs that do fine without null move, one of which I know >very well. > >I guess that adding null move to these programs would degrade their >performances, because it would simply be too much pruning. > >Adding null move to a pure alphabeta searcher like Deep Blue would improve it >tremendously, that's what I meant. > > maybe or maybe not. It isn't clear how a recursive null move search interacts with singular extensions. They are sort of "opposites" when you think about it. DB's results are already good enough for me. I wish my program was that strong... > >> Why is it such an impossibility for DB's selective search to not >>require it when some PC programs don't use it either? > > >Every competitive PC program uses a selective search. > >Null move is only one selective system amongst others. > > > > Christophe
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