Author: Slater Wold
Date: 05:30:02 03/07/02
Go up one level in this thread
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. Not so in either case here. I am not sure what's going on. But thanks for trying to explain. :)
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