Author: Slater Wold
Date: 10:42:33 03/07/02
Go up one level in this thread
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. > > > > > >> >>Not so in either case here. I am not sure what's going on. But thanks for >>trying to explain. :)
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