Author: Robert Hyatt
Date: 11:54:10 03/07/02
Go up one level in this thread
On March 07, 2002 at 13:42:33, Slater Wold wrote: >On March 07, 2002 at 10:40:19, Robert Hyatt wrote: > >>On March 07, 2002 at 08:30:02, Slater Wold wrote: >> >>>On March 07, 2002 at 03:43:00, Uri Blass wrote: >>> >>>>On March 07, 2002 at 00:42:56, Slater Wold wrote: >>>> >>>>>On March 06, 2002 at 23:40:28, Robert Hyatt wrote: >>>>> >>>>>>On March 06, 2002 at 22:49:38, Slater Wold wrote: >>>>>> >>>>>>>On March 06, 2002 at 22:27:17, Uri Blass wrote: >>>>>>> >>>>>>>>On March 06, 2002 at 19:18:16, Slater Wold wrote: >>>>>>>> >>>>>>>>>Hyatt said in an earlier post that TB's don't take into account the ability to >>>>>>>>>castle because it would be a waste. >>>>>>>>> >>>>>>>>>However, when I feed this position into any engine, it solves it in 0.00 as a TB >>>>>>>>>win. >>>>>>>>> >>>>>>>>>[D]5Q1Q/5Q1Q/5Q1Q/5Q1Q/8/6P1/6k1/4KR1R w K - >>>>>>>> >>>>>>>>Your FEN is wrong and we need to imagine that all the white queens that you >>>>>>>>copied from dann corbit's post are missing. >>>>>>> >>>>>>> >>>>>>>You're right. But obviously this is not the position I am talking about, >>>>>>>because I don't have the 13 man TB's. :) >>>>>>> >>>>>>> >>>>>>>>>It shows 20 possible moves, all from TB's I am guessing. >>>>>>>>> >>>>>>>>>I cannot cut and paste the eval, because there isn't one, but I have: >>>>>>>><snipped> >>>>>>>>>1.+ - (#4) Rf4 >>>>>>>> >>>>>>>>This is not correct and the program that you use has bugs. >>>>>>>>It should not call tablebases in a position that is not in the >>>>>>>>tablebases(castling is legal) >>>>>>>> >>>>>>>> >_Several_ of these moves take castling into accout. >>>>>>>>> >>>>>>>>>After Rf4 Kxg3 my TB's show 28 moves. The first move is 1. + - (#2) O-O, the >>>>>>>>>last is 28. + - (#15) Rh8. >>>>>>>>> >>>>>>>>>I am 100% sure TB's do indeed take castling into consideration. >>>>>>>> >>>>>>>> >>>>>>>>No >>>>>>>>You do not understand how tablebases work. >>>>>>>>There are no moves in tablebases. >>>>>>>> >>>>>>>>The engine generates all the legal moves and looks in the tablebases after these >>>>>>>>moves to see distance to mate. >>>>>>> >>>>>>> >>>>>>>Um, well, according to Hyatt, it would tell the TB "o-o" and it wouldn't return >>>>>>>anything. I am very well aware how TB's work. >>>>>> >>>>>>Not quite. First I _never_ said anything like that. With EGTB's you don't >>>>>>give them a move, and get back a score, you give them a _position_ and you get >>>>>>back a score. And the score says "mate in N from the given position, >>>>>>assuming castling is impossible." >>>>>> >>>>>> >>>>>> >>>>>>> >>>>>>> >>>>>>>>If castling is legal then the engine looks at the tablebases to see the distance >>>>>>>>to mate after castling in order to see the mate in 2 score. >>>>>>> >>>>>>> >>>>>>>According to Hyatt, no it doesn't. >>>>>> >>>>>> >>>>>>You are greatly twisting things around. Re-read what Uri wrote... >>>>>> >>>>>>"if castling is legal then the engine only checks the TB _after_ castling >>>>>>has been done." Because after castling has been done, it can't be done again >>>>>>and the resulting EGTB score will be correct. Prior to castling, the score >>>>>>will be wrong because castling is possible but the EGTB scores don't include >>>>>>castling. >>>>>> >>>>>> >>>>>> >>>>>> >>>>>>> >>>>>>> >>>>>>>>Uri >>>>>>> >>>>>>>The correct position is: >>>>>>> >>>>>>>[D]8/8/8/8/8/6P1/6k1/4KR1R w K - >>>>>>> >>>>>>>Sorry. >>>>> >>>>>I am not trying to "twist" anything around. You said TB's don't take into >>>>>account castling. Ok, fine. I believe you. I open a chess engine, and it's >>>>>returning o-o as a TB move. NO EVAL NEEDED. I am asking a simple question. >>>>>Why?! How is an engine returning a mate, without TB's, without an eval? >>>>> >>>>>If it's a stupid question, I apologize. I just don't understand, obviously. >>>> >>>>Very simple answer >>>> >>>>0-0 is not a tablebase move because the tablebases have no moves but >>>>only positions and evaluations. >>>> >>>>The position after 0-0 is a tablebase position. >>>>The engine tries every legal move and look at the tablebases >>>>to get a score for the position after the move. >>>> >>>>I can add that the way the engine is using tablebases is wrong >>>>and it can cause mistakes >>>>on positions when the only win is based on the idea to castle in the second move >>>>and not in the first move. >>>> >>>>In this case the engine may return draw score for every move because it is going >>>>to look at the tablebases that are based on the assumption that >>>>castling is illegal in the future. >>>> >>>>It is of course not important for practical games because castling is not >>>>allowed in practical games so I understand programmers who choose not to fix the >>>>problem. >>>> >>>>Uri >>> >>>Thanks Uri. But I am still not convinced. >>> >>>When I put this position into a CB engine, I can monitor CPU usage, and I know, >>>it _never_ uses the CPU. o-o doesn't not have an eval. >>> >>>Last time I checked, when an engine "evaluates" a problem, it gives an eval. It >>>also usually uses some CPU time. >> >>Evaluating a single position takes what? a millisecond? You think you >>could see that on the CPU meter? If the position at the root of the tree >>(the position after o-o) is a tb position, the computer makes every possible >>move, one at a time, and then probes the TB. It chooses the move that has the >>best possible TB score. It is _definitely_ doing some work. But the work is >>a few milliseconds at most, a few microseconds at best. You can't see that on >>a "cpu meter"... > > >Windows 2000 Advanced Server will "meter" CPU time in microseconds. And that is >system based, or program based. > >K. Thanks. > Then you should _never_ see "no cpu usage". It takes cpu time to simply parse the input move you type... > >> >> >> >> >> >>> >>>Not so in either case here. I am not sure what's going on. But thanks for >>>trying to explain. :)
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