Author: Miguel A. Ballicora
Date: 15:53:46 05/20/01
Go up one level in this thread
On May 20, 2001 at 14:47:12, Christophe Theron wrote: >On May 20, 2001 at 14:26:15, Vine Smith wrote: > >>On May 20, 2001 at 13:24:29, Christophe Theron wrote: >> >>>On May 20, 2001 at 04:25:41, Frank Phillips wrote: >>> >>>>On May 19, 2001 at 23:48:48, Christophe Theron wrote: >>>> >>>>>On May 19, 2001 at 23:37:31, Ratko V Tomic wrote: >>>>> >>>>>>>I'm extremely surprised that my creature managed to survive more >>>>>>> than 30 moves, given a 300 times speed handicap. >>>>>> >>>>>>The flip side is that the current programs running at some >>>>>>future machines at 300 GHz won't be able to crush the current >>>>>>programs on 1 GHz any more convincingly (in terms of how >>>>>>many moves the slower machine can hang on) than what happened >>>>>>in this matchup. >>>>>> >>>>>>This is the same effect that many players have experienced >>>>>>when upgrading their hardware to 2-3 times faster one and >>>>>>then being disapponted, after all the expense and hopes, >>>>>>when they can't even notice any difference in the perceived >>>>>>program strength (aginst humans). >>>>> >>>>> >>>>> >>>>>You are absolutely right. >>>>> >>>>>I think we are already beginning to experience the effects of dimishing returns >>>>>in chess on current hardware at long time controls. >>>>> >>>>> >>>>> >>>>> Christophe >>>> >>>>Would someone take the time to explain this simply and clearly, to me. I can >>>>understand that if you are already beating humans (or some other group of >>>>players) most of the time, then increasing the speed still means you are beating >>>>them most of the time and maybe a bit more, but until a machine can see _all_ >>>>there is to see how would it not improve by seeing more and how can you say >>>>(apriori) that it will improve only at a diminishing return? In other words, I >>>>can believe that results against a set of players is aysomtopic, tending towards >>>>100 percent, but do see why this is necessarily true of the game played by two >>>>otherwiseequally matched entities. >>> >>> >>> >>>In my opinion it has to do with the fact that in a given chess position the >>>number of moves is limited. Generally you have between 20 and 50 legal moves. >>> >>>From these moves, only an even more limited subset does not lead to an obvious >>>loss. >>> >>>And from this subset there is an even more limited subset of moves (2 or 3 >>>generally) that can be played, and chosing between them is a matter of >>>preference because the amount of computation needed to prove which one is better >>>is too big for any computer. >>> >>>So once you reach the stage where you can see which 2 or 3 moves are playable, >>>it would take an additional huge computation to see further. >>> >>>I think some chess programs on current computers at long time controls have >>>already reached this stage, and this is why is becomes increasingly difficult to >>>say which one is better. >>> >>>This is a very simplistic explanation which lacks mathematical support, I know, >>>but that's how I explain dimishing returns. >>> >>> >>> >>> Christophe >> >>Is it possible that there is also a problem with bad evaluations infecting whole >>branches in the tree of analysis? In Fritz vs. Gambit Tiger at Leiden, Fritz >>played 21.b4, shutting in its queen. Was this not a dreadful move? Yet, I had >>Fritz analyze after this point through 18 ply, and the evaluation was just +0.06 >>(after which it mysteriously halted analysis). And Tiger 14 has reached 20 ply >>looking at this same position, with an evaluation of just +0.46 after 21...Nc3 >>22.Rd3 Qf6 23.Kf1 Ne4 24.Bd4 Qf7 25.Bb2 g5 26.Rde3 Bf4 27.Bxe4 fxe4 28.Rxe4 Rxe4 >>29.Rxe4 Qxd5 30.Re7. Actually, the final position is lost for White after >>30...Qd3+ 31.Re2 Qb1+ 32.Ne1 Bf5, but White doesn't need to play 30.Re7. The >>point is that neither program, given even 10-12 hours to think (on a PIII 850) >>appreciates the disastrous effects of White's missing queen. As poor evaluations >>like this clog up the search, all lines begin to look like one another, despite >>huge differences between them that would be clear to any human player examining >>these positions. >>Regards, >>Vine Smith > > > >I do not agree. > >Tiger KNOWS about the bad position of the Queen after b4 and would never play >this move. > >If you try, you will see that Tiger's evaluation is different in the lines the >queen is trapped and in the lines it is not. > >The evaluation difference is not big, but it is enough to avoid such a >disastrous move in almost all the cases, and to try to find a way to free the >queen if it happens to be trapped by a long sequence of forced moves. > >Tiger is able to identify some cases of blocked pieces or pieces with poor >mobility in its evaluation. In particular, it is able to see that the queen is >blocked after b4? and gives a penalty for this. I have worked hard in this part >of the evaluation, so I can't let you generalize and say that any program would >ignore the consequences of the trapped queen. Mine knows. Even mine knows :-) Yes, my program sucks but my point is that it is a matter of tuning the evaluation, it is now mission impossible. Vine, I post the results before in case that you miss the post (it is easy with so much traffic) http://www.icdchess.com/forums/1/message.shtml?170629 Regards, Miguel > > > > Christophe
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