Author: Steve Coladonato
Date: 07:31:39 05/04/00
Go up one level in this thread
On May 04, 2000 at 10:06:28, Robert Hyatt wrote: >On May 04, 2000 at 08:13:51, Steve Coladonato wrote: > >>On May 03, 2000 at 18:26:09, Robert Hyatt wrote: >> >>>On May 03, 2000 at 12:52:01, Steve Coladonato wrote: >>> >>>>On May 03, 2000 at 10:38:57, blass uri wrote: >>>> >>>>>On May 03, 2000 at 09:41:19, Steve Coladonato wrote: >>>>> >>>>>>On May 03, 2000 at 03:29:48, Jouni Uski wrote: >>>>>> >>>>>>>On May 02, 2000 at 13:03:47, Steve Coladonato wrote: >>>>>>> >>>>>>>>There is a correspondence match going on between Steve Ham and both Fritz 6(a) >>>>>>>>and Nimzo 7.32. The games are documented at the following site: >>>>>>>> >>>>>>>>http://correspondencechess.com/campbell/index.htm >>>>>>>> >>>>>>>>They appear to be quite interesting and the analysis by Mr. Ham is very >>>>>>>>extensive. It's interesting that even after 19-21 hrs of evaluation, the >>>>>>>>computers are only getting to 15-16 ply. Also, it looks like Mr. Ham has the >>>>>>>>upper hand in the games. >>>>>>>> >>>>>>>>Regards. >>>>>>>> >>>>>>>>Steve >>>>>>> >>>>>>>I am not so sure if Ham has upper hand. And note, that most moves were played in >>>>>>>3-best move mode! >>>>>>> >>>>>>>Jouni >>>>>> >>>>>>Jouni, >>>>>> >>>>>>What is "3-best move mode"? >>>>> >>>>>Chessbase engines can search the 3 best move instead of only searching for the >>>>>best move. >>>>> >>>>>They did it in the beginning of the game and probably they could search more >>>>>deep by searching only for the best move. >>>>> >>>>>searching for 3 best moves instead of only the best move is about the same as >>>>>being 2-3 times slower. >>>>> >>>>>Even if we do not assume diminishing return from being 2-3 times faster >>>>>the demage for programs in this case is not more than 100 elo and if we consider >>>>>also the fact that the programs did it only in the opening the demage is >>>>>probably less than 50 elo so it will probably not change the reuslt of the match >>>>>because the expected changed in the result is less than 0.25 point >>>>> >>>>>Uri >>>> >>>>Uri, >>>> >>>>When a computer engine evaluates a position, does it not take all the possible >>>>moves and compute an evaluation for each move? In this case the three "highest" >>>>scores would be the top three and there is really no effect on the processing. >>>>I understand that variations within a given move are also calculated but is this >>>>not just normal processing? >>>> >>>>Steve >>> >>> >>>no. Alpha/beta finds the best move and only proves that the other moves are >>>worse, without proving how much worse they are. To do this requires a lot more >>>time. >> >>You have both given me essentially the same answer. I've never looked at the >>code for a chess engine so I don't know exactly what Alpha/Beta does. But the >>answers here are confusing to me. I was under the impression that the best move >>was determined by calculating the eval for the candidate moves. Your answers >>are implying that that is incorrect and something else is used to determine the >>best move, not the eval for the position. But if that is the case, is not what >>the program calculates somehow related to the eval? And if so, saving the >>result in an array would not incur that much more overhead so that the program >>would know what the top three moves are or rather the order of all candidate >>moves based on whatever it is calculating. >> >>Steve > > >Here is the idea: > >You have three holes in the wall. Your task is this: "stick your hand in >each hole, for exactly one minute, and then report which one gave you the >most pleasant (or least unpleasant) experience." > >You stick your hand in hole #1. For one minute, you get nothing but warm >water. You stick your hand in hole #1. You are instantly greeted by very >hot water. This is already more unpleasant than holee #1. Do you wait around >to see if it gets to the boiling point or do you leave _right now_. I leave >now, as I have already proved that it is worse than #1. I don't know how much >worse yet (to discover this I have to wait for the full minute). I go on to >hole #3 and immediately get doused by salt-water at about 30 degrees F. That >is very cold and much worse than hole number one. Do I stick around to see if >it gets worse, or do I quit not? > >Total time spent = 1 minute in hole 1, 1 sec in hole 2, one sec in hole 3. I >only proved that 2 and 3 were worse, but not how much worse. > >That is how alpha/beta works. That makes sense. But let's start with hole #2 first. So now I stick my hand in, get doused with very hot water but hang around for a minute. Now I go to hole #1 and get greeted with warm water. Nice. So now the best move is hole #1 not hole #2. But do I hang around in hole #1 for a while or immediately move on to check hole #3. And what about that shark that's about ready to snatch off my hand should I dally a bit longer in hole #1. It seems like the best move is determined by a very superficial ply movement once something is deemed to be best. But maybe the best move is actually that knight sac (very cold water) that is rewarded 6 ply later. Of course I can't argue with success. Am I correct in now believing that ply depth has nothing to do with best move? Steve
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