Author: Uri Blass
Date: 12:45:12 09/01/01
Go up one level in this thread
On September 01, 2001 at 15:06:05, Slater Wold wrote: >On September 01, 2001 at 11:00:37, Ed Schröder wrote: > >>On September 01, 2001 at 09:55:25, Robert Hyatt wrote: >> >>>On September 01, 2001 at 08:48:00, Vincent Diepeveen wrote: >>> >>>> >>>>You are entirely right Ed, i have singular extensions inside diep now >>>>and play with them turned on tournaments now. first tournament i played >>>>with them turned on was back in 1994 the dutch open championship, >>>>but my implementation sucked bigtime there. Then in paderborn 2001 i >>>>used a better implementation with big reduction factor (R=3) and >>>>also in combination with other extensions. The reason i have them >>>>inside diep now is >>>> a) diep doesn't search very deeply so overhead isn't too big then >>>> b) to solve testpositions quicker otherwise i need days to solve things >>>> >>>>However what i notice is that in mainlines in complex positions the >>>>value of singular extensions is very limited. Of course if i'm already >>>>won i see mates way before my opponent sees them (in middlegame) or >>>>i see a win way before my opponent sees it, as well as that Rxf7 move >>>>which ferret played against gandalf i see within seconds with within 90 >>>>seconds the right score, but after all the only impact of singular extensions >>>>is that they give a psychological good feeling "i'm not going to lose >>>>because of a cheap trick if my program messes up". Of course combinations >>>>can only be there and getting outsearched is only important if a program >>>>plays completely anti positional chess. >>>> >>>>In normal game play and in sound positions, there the value of SE and similar >>>>extensions gets hugely overrated i think. >>> >>> >>>I don't believe they _hurt_ when done right. The _last_ report by the DB >>>team suggested that SE was worth maybe 10-20 Elo rating points at most. Their >>>first report suggested far greater improvement, but this was because it did far >>>better on test suites. In matches, it won, but the margin of victory was much >>>less than the test suite results suggested... >>> >>>My tests in CB produced the same results. Modest improvements in games, some- >>>times wild improvements in test positions. But even though the improvement in >>>games is very modest, that one game here or there is _still_ very important. >>>That could be your game vs Kramnik in a big tournament, for example. >> >> >>Then why is SE not in Crafty when SE is an improvement? >> >>Ed > >I believe SE isn't going to hurt you when you're searching 200M nodes a second. > >Perhaps when you're search 1.0M or 1.5M, perhaps that extra squeeze of depth is >not worth it, when it's taking up valuable time. > >Slate I believe that you are wrong. Deeper search without singular extensions is always important Deeper blue could not see the move Qe3 in the pv against kasparov when top programs of today can see it programs change their mind also at long time control because deep search helps them to discover new things. I have examples from my correspondence games when Deep Fritz changes it's mind after many hours to a better positional move because of deep search and I believe that it could not see it with singular extensions. Uri
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