Author: Albert Silver
Date: 13:20:17 06/18/01
Go up one level in this thread
On June 18, 2001 at 15:46:13, Bas Hamstra wrote: >On June 18, 2001 at 13:05:38, Robert Hyatt wrote: > >>On June 18, 2001 at 10:51:12, Bas Hamstra wrote: >> >>>On June 18, 2001 at 08:33:21, Ulrich Tuerke wrote: >>> >>>>On June 18, 2001 at 08:28:08, Bas Hamstra wrote: >>>> >>>>>On June 17, 2001 at 01:09:50, Robert Hyatt wrote: >>>>> >>>>>>On June 16, 2001 at 22:59:06, Vincent Diepeveen wrote: >>>>>> >>>>>>>Hello, >>>>>>> >>>>>>>From Gian-Carlo i received tonight a cool version of crafty 18.10, >>>>>>>namely a modified version of crafty. The modification was that it >>>>>>>is using a small sense of Singular extensions, using a 'moreland' >>>>>>>implementation. >>>>>>> >>>>>> >>>>>> >>>>>>Instead of modifying Crafty to simulate Deep Blue, why didn't you >>>>>>modify Netscape? Or anything else? I don't see _any_ point in >>>>>>taking a very fishy version of crafty and trying to conclude _anything_ >>>>>>about deep blue from it... >>>>>> >>>>>>Unless you are into counting chickens to forecast weather, or something >>>>>>else... >>>>> >>>>>I don't agree here. It is fun. Maybe not extremely accurate, but it says >>>>>*something* about the efficiency of their search, which I believe is horrible. I >>>>>think using SE and not nullmove is *inefficient* as compared to nullmove. We >>>>>don't need 100.0000% accurate data when it's obviously an order of magnitude >>>>>more inefficient. >>>> >>>>May be you are right, if the program is running on a PC. However if you can >>>>reach a huge depth anyway because of hardware, may be you can afford to use >>>>this, because it doesn't matter too much wasting one ply depth ? >>> >>>I don't see why inefficiency becomes less of a problem at higher depths. >>>Nullmove pruning reduces your effective branching factor to 2,5 where brute >>>force gets 4,5. So you could suspect at higher depths the difference in search >>>depths grows, starting with 2 ply, up till how much, 5 ply? >> >>Several things here. First a normal alpha/beta program does _not_ have a >>branching factor of 4.5... it is roughly sqrt(n_root_moves) which is closer >>to 6. > >Not at all. Have you never tried Crafty without nullmove? See below my engine >output, rootposition. Where is the 6? I have never had 6, in my opinion 4,5 on >average is normal. > >Hash 8 Mb >PawnHash 4 Mb >Hashing 524288 positions >PHash 65536 records >Evaluation learning 50 >Could not open Tao.bk for input >Ok[book] >Book[No] >Ok[analyze] >TargetTime set[4750] > 1. 25 0 25 d2d4 > 2 0 0 52 d2d4 d7d5 > 2. 0 0 91 d2d4 d7d5 > 3 27 0 173 d2d4 d7d5 c1g5 > 3. 27 0 661 d2d4 d7d5 c1g5 > 4 -2 0 1219 d2d4 d7d5 c1g5 g8f6 > 4. -2 0 2206 d2d4 d7d5 c1g5 g8f6 > 5 22 0 4611 d2d4 d7d5 g1f3 c8f5 c1g5 > 5. 22 0 13223 d2d4 d7d5 g1f3 c8f5 c1g5 > 6 0 0 24494 d2d4 d7d5 g1f3 c8f5 c1f4 g8f6 > 6 8 1 52306 e2e4 e7e5 g1f3 g8f6 f1c4 b8c6 > 6. 8 1 64702 e2e4 e7e5 g1f3 g8f6 f1c4 b8c6 > 7 19 2 185234 e2e4 d7d5 e4d5 d8d5 g1e2 c8g4 d2d4 > 7. 19 3 311857 e2e4 d7d5 e4d5 d8d5 g1e2 c8g4 d2d4 > 8 11 6 686116 e2e4 b8c6 d2d4 d7d5 e4d5 d8d5 g1f3 c8f5 > 8. 11 9 978711 e2e4 b8c6 d2d4 d7d5 e4d5 d8d5 g1f3 c8f5 >Ok[quit] > >>Second, if you look at DB's log files for the kasparov match, you will find >>their branching factor is well below 4.0... > >So 4 is close to normal, I would say. > >>>Of course nullsearch has holes, but they are certainly not big enough to offset >>>a couple of plies, or none would use nullmove! In practice a n ply nullmove >>>search sees more than a n-2 ply BF search. >>> >>>Keeping that in mind, give Crafty 1000x faster hardware. It would search at >>>least 20 ply (normally 13 average according to Bob plus at least 7). I can tell >>>you DB does not search 18 ply BF. Therefore Crafty would in principle see more, >>>given the same eval. The SE thing only makes it worse. >> >>Again, I can tell you that DB did search 16-18 plies deep. We have that in >>the log files and as direct quotes from the team members. If you can get that >>deep without null-move, is another couple of plies _really_ worth all the >>nonsense that null-move search causes? zugzwang problems. fail high/fail low >>problems. Tactical oversights. Etc. > >Not convincing. Several times you have said deeper is better, and there is no >"tactical barrier". I agree. And nullmove gets you there which is more important >than the sideeffects. What evidence do you have that beyond 15 ply suddenly >different laws apply? Didn't Heinz recently publish a paper on diminishing returns? Albert
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