Author: Eugene Nalimov
Date: 09:15:52 01/13/05
Go up one level in this thread
On January 13, 2005 at 11:08:48, Robert Hyatt wrote: >On January 13, 2005 at 05:36:41, Tony Werten wrote: > >>Hi all, >> >> >>when checking my own tables, I found out that the following (illegal ) position, >>causes the Nalimov code( rather, the decompresssion code ) disabled further egtb >>probes. >> >>No problem for normal use, just when you're doing something without checking if >>the position is legal, it goes wrong. >> >>The position looks like it might have been optimized away, causing a probe >>beyond the uncompressed size of the filechunck just read in, causing an >>"invalid" flag on the tablebase, resulting in a disabling of the KNNkp >>tablebase. >> >>[D]4K3/8/8/k7/8/1N6/p7/N7 w - - 0 0 >> >>Tony > > >I believe this has always been a restriction. Since one way to compress the >database (before the raw compression algorithm) is to weed out positions that >are not possible, such as two kings on adjancent squares, both kings in check, >pawns on illegal squares, etc. I suppose the probe code could be modified to do >all the legality checks, but then it would have to be able to generate moves to >see if a king is in check and the other side is on move, etc. It makes more >sense for the chess engine to do that stuff since it knows about legality issues >anyway... > >Perhaps Eugene will comment further... If you pass illegal position you'll get back either "unknown value" (if you are lucky), or value for some other position. I definitely would not turn off further probing, but chess engine can. Thanks, Eugene
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.