Author: Robert Hyatt
Date: 14:46:10 08/16/05
Go up one level in this thread
On August 16, 2005 at 17:37:30, Uri Blass wrote: >On August 16, 2005 at 17:30:02, Paolo Casaschi wrote: > >>On August 16, 2005 at 17:26:28, Dann Corbit wrote: >> >>>On August 16, 2005 at 17:16:33, Paolo Casaschi wrote: >>> >>>>>I know that usually when program improve they improve in all time controls. >>>>>I do not know of evaluation changes or search changes that make programs weaker >>>>>at blitz but stronger at long time control. >>>>> >>>>>In thoery it can happen but I need to see a proof for it and I believe that >>>>>fabien mainly test in blitz time control(he can correct me if I am wrong) >>>>>because usually productive changes in blitz of adding knowledge to the >>>>>evaluation are also productive at long time control. >>>> >>>>Do you have any proof or evidence that there is some correlation between blitz >>>>strenght and slower speed strenght? >>>>If you dont, then we can only compare assumptions and I tend to agree with Bob >>>>Hyatt since the same non-correlation is evident with humans and because common >>>>sense... >>> >>>There is definitely a general correlation between strength at blitz and strength >>>at standard time control. However, there are also exceptions to the rule. >>> >>>For instance, we will expect Fruit to be stronger than Golem at blitz, in the >>>same way that we would expect Kasparov to clobber me at blitz. >>> >>>On the other hand, Mike Valvo overperforms at blitz, and Amy used to >>>underperform badly (it was mostly due to bad algorithms for time management at >>>fast time control). >> >>Exactly my point. >>There is some correlation but there are exceptions and it's possible that >>different players have a different type of correlation, thus the point of Bob >>Hyatt stands. >> >>--Paolo > >I still need to see an example for programs without significant bugs that show >significant difference(Amy is not a good example because of bad time management) > >There may be cases when A is 50 elo weaker at blitz and 50 elo better at long >time control but I doubt if you can find cases when A is 100 elo weaker at blitz >and 100 elo stronger at long time control. > >Uri I'm not going to waste all day here, but a parallel search program can play worse in endgames than in the middlegame, if sufficient care is not taken. Would you really want to sic 8 cpus on a position which on average only has 4 moves or less? Overhead goes thru the roof. Same thing happens in blitz. Trees are a fraction of their normal size. To split them invites excessive search overhead. In extreme cases (I have seen this in Crafty) I get to do _zero_ splits in a blitz game (this happened in a couple of the games Peter played today in fact) which means the search is running about 1/6 its normal performance level. Think a factor of 6 slower will make a measurable difference in speed vs normal chess? Easily. over-compensate for that and you greatly slow the search down by having excessive split overhead. And screwing up on this side of the equation can make the parallel search _slower_ than a single-processor search, which can totally wreck performance... Enough of this for the moment. The problem is real...
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