Author: Robert Hyatt
Date: 07:37:54 03/07/02
Go up one level in this thread
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. Simple. The engine makes the move o-o. It then gives the resulting position to the TB probe code which looks up the position and returns the score. Since you are giving it a position _after_ castling the mate score will be perfect. Suppose it returns mate in 2 for the position _after_ castling. If you give it the position _before_ castling it might return mate in 5 or anything else because that mate was achieved _without_ trying the move o-o when generating the tablebase...
This page took 0 seconds to execute
Last modified: Thu, 15 Apr 21 08:11:13 -0700
Current Computer Chess Club Forums at Talkchess. This site by Sean Mintz.