Author: Miguel A. Ballicora
Date: 23:05:10 05/20/01
Go up one level in this thread
On May 21, 2001 at 01:15:18, Vine Smith wrote: >On May 20, 2001 at 18:53:46, Miguel A. Ballicora wrote: > >>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 >Hi -- >I did miss it -- thanks for referring me to the message, because I was glad to >finally see an evaluation that more or less matches my perception of the >disastrous nature of 21.b4. I must certainly do some testing with Gaviota, to >see if this positional sense it displays here is reflected in its evaluation of >other positions. Also, Gaviota's preferred 21.Re2 was my first thought when >looking for alternatives to 21.b4. I'm baffled by not only Fritz's choice, but >also the number of programs that think 21.b3 is the best idea here. I don't see >problems with the b-pawn; if there are any, then Crafty's choice of 21.Bc1 has >to be superior to moving the pawn, which just creates additional weaknesses. >Regards, >Vine Gaviota is a *weak* winboard engine in development. If Gaviota can beat fritz in this position, it will prove a point about that the position is disastrous. I can assure you that gaviota will try to keep the queen trapped. I do not have Fritz, otherwise I will try it myself. Gaviota has some kind of learning implemented, so you can even play a match. I believe that the position is so bad that I won't be easy for Fritz... If you want to download it, it is in http://www.msu.edu/~ballicor/gav Regards, Miguel PS: let me know if you try it.
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