Discussions (not only) about Xboard/Winboard, Computer Chess and Chess Programming
by Sune Fischer » 03 Jun 2004, 23:00
How can it be the GUI's fault when it is supporting the FEN standard? If anything, it is the fault of the FEN standard.
Regards
Dave
by Fabien Letouzey » 04 Jun 2004, 09:54
As far as I know XBoard/WinBoard do not know about en passant or castling rights (and of course many other rules). That's one of the reasons why the engines have to act as referees during the games.It's a bug in Winboard 4.2.6, it removes the e.p. information from the FEN.How can it be the GUI's fault when it is supporting the FEN standard? If anything, it is the fault of the FEN standard.
Regards
Dave
I don't know if it has been fixed in the new version.
-S.
by Sune Fischer » 04 Jun 2004, 11:56
Winboard does know a few things and apparently edits the FEN using some internal logic.As far as I know XBoard/WinBoard do not know about en passant or castling rights (and of course many other rules). That's one of the reasons why the engines have to act as referees during the games.It's a bug in Winboard 4.2.6, it removes the e.p. information from the FEN.How can it be the GUI's fault when it is supporting the FEN standard? If anything, it is the fault of the FEN standard.
Regards
Dave
I don't know if it has been fixed in the new version.
-S.
Tournament directors and engine authors have problems because the interface cannot even (fully) test the legality of moves!
Fabien.
by Fabien Letouzey » 04 Jun 2004, 12:19
I think I remember that XBoard/WinBoard never handled either castling or en-passant rights internally. When in doubt they will always send the potentially-legal move to the engine and expecting it to test for legality.Winboard does know a few things and apparently edits the FEN using some internal logic.
You can try a FEN with castle rights and kings on d-file, winboard will remove the castle rights before sending it to the engine.
It does a similar thing to the e.p. information, only in that case it's incorrect.
I guess the validity detector for the e.p. information is broken or something, winboard always thinks it's illegal.
-S.
by Fabien Letouzey » 04 Jun 2004, 13:01
Yes I think the logic is the following:Winboard does know a few things and apparently edits the FEN using some internal logic.
by Sune Fischer » 04 Jun 2004, 13:05
If the doc says that then there is an error in the doc.I think I remember that XBoard/WinBoard never handled either castling or en-passant rights internally. When in doubt they will always send the potentially-legal move to the engine and expecting it to test for legality.Winboard does know a few things and apparently edits the FEN using some internal logic.
You can try a FEN with castle rights and kings on d-file, winboard will remove the castle rights before sending it to the engine.
It does a similar thing to the e.p. information, only in that case it's incorrect.
I guess the validity detector for the e.p. information is broken or something, winboard always thinks it's illegal.
-S.
The doc files will confirm this I think.
Alternately you can try "Reset Game", "Edit Game" then you play 1. e4 d5 2. e5 e6 3. exd6 (illegal) and verify that WinBoard sends it to the engine even when "Test Legality" is selected.
WinBoard is a graphical display for chess pieces, it only knows part of the rules.
Fabien.
by Fabien Letouzey » 04 Jun 2004, 13:13
I explain why in my other post.Just take any engine and hook it up, give a FEN to winboard and print out what
the engine recieves, it's clearly an edited FEN.Move legality testing is not the same as FEN legality testing.Alternately you can try "Reset Game", "Edit Game" then you play 1. e4 d5 2. e5 e6 3. exd6 (illegal) and verify that WinBoard sends it to the engine even when "Test Legality" is selected.
From what I can tell there are no bugs in the move legality part.
by Sune Fischer » 04 Jun 2004, 13:16
Okay, so winboard breaks up the FEN and then re-assembles it.Yes I think the logic is the following:Winboard does know a few things and apparently edits the FEN using some internal logic.
1) en-passant information is always empty (not removed because it was never stored in WinBoard's data in the first place)
2) if a king and rook are on their original squares, emit the corresponding castling right (regardless of whether they have moved before or not).
I have checked for castling rights: 1. e4 e5 2. Ke2! Nf6 3. Ke1!! then output the FEN string, white is allowed to castle.
Fabien.
by Sune Fischer » 04 Jun 2004, 13:33
Apparently my knowledge of that was not complete, you're right winboard does allow an illegal move even with legality testing on.I explain why in my other post.Just take any engine and hook it up, give a FEN to winboard and print out what
the engine recieves, it's clearly an edited FEN.Move legality testing is not the same as FEN legality testing.Alternately you can try "Reset Game", "Edit Game" then you play 1. e4 d5 2. e5 e6 3. exd6 (illegal) and verify that WinBoard sends it to the engine even when "Test Legality" is selected.
From what I can tell there are no bugs in the move legality part.
My other post explains my reasoning more clearly, I hope.
Do you mean that WinBoard rejects my illegal 3. exd6 by itself?
That would indeed invalidate my explanation, just let me know.
Fabien.
by Dieter Bürßner » 04 Jun 2004, 21:53
Matthias, I cannot reproduce this with either Shredder 5/6/8 Classic. They all seem to send move lists as expected, here.it was in ordinary engine-engine matches (nothing pasted).
I would have to install at least Shredder6Classic again to find out.
If I do it, I will inform in this forum.
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