Talk:Forsyth–Edwards Notation

message: Anyone knows if the letters for pieces (KQRBNP) are strictly defined by this standard?
If, for example, I use FIDE approved letters, will it invalidate the FEN?
--217.198.225.76 22:02, 16 Nov 2004 (UTC)
replies: text: Because it can and does stretch the diagram display especially in Firefox. Looking at the situation at present to see if it can be resolved somehow. ChessCreator (talk) 17:53, 31 March 2008 (UTC)
replies: text: That isn't a good reason. --Zzo38 (talk) 05:00, 24 December 2012 (UTC)
thread_title: Standards

message: Here is the FEN after the move 1. e4:
:rnbqkbnr/pppppppp/8/8/4P3/8/PPPP1PPP/RNBQKBNR b KQkq e3 0 1
Is this correct? Although a pawn has moved 2 forward, no en-passant is actually possible. Evercat (talk) 16:37, 10 June 2010 (UTC)
replies: text: I think that is correct.  The en passant square is listed if the last move was a two-square pawn move, whether e.p. is possible or not.  Of course, it would not really hurt anything to leave it off if no e.p. is possible.  From the article: "This is recorded regardless of whether there is a pawn in position to make an en passant capture."Bubba73 (You talkin' to me?), 17:16, 10 June 2010 (UTC)
thread_title: En-passant square when no en-passant possible

message: The second introductory paragraph states, "FEN does not represent sufficient information to decide on draws by [...] the fifty-move rule." However, the fifth item of FEN is apparently "used to determine if a draw can be claimed under the fifty-move rule." I'm not a frequent user of FEN, but it seems the half-move clock is sufficient for establishing a draw by this rule. Unless someone else has reason to believe it isn't, I'll remove the relevant statement from the introduction.--TrippingTroubadour (talk) 01:31, 2 July 2010 (UTC)
replies: text: I believe you are right!  Bubba73 (You talkin' to me?), 03:18, 2 July 2010 (UTC)

text: Can you use "-" if you don't know the halfclock? --Zzo38 (talk) 05:00, 24 December 2012 (UTC)
thread_title:  Fifty-move rule 

message: Chess960 starting position rules do not allow both rooks to be on one side of the king. "This leaves three empty squares. Place the king on the middle empty square, and the rooks on the remaining two squares." The rules of Chess960 make the following statement superfluous. "However, the FEN castling availability encoding (KQkq) is inadequate for positions in which there are two Rooks on the same side of the King on the back rank. It is ambiguous which Rook is still available for castling without knowing their initial positions."  — Preceding unsigned comment added by 151.193.220.28 (talk) 15:23, 5 September 2012 (UTC)
replies: text: Came across the same question myself. It was well explained here http://www.dwheeler.com/essays/Fischer_Random_Chess.html. If in the game the other rook comes to the same side of the king as the rook with castling right, then it is ambiguous. Ketorin (talk) 16:56, 1 March 2015 (UTC)
thread_title:  FEN adjustment for chess variants like Chess960 

message: Interesting that FEN is actually "overspecific", in that the same position can be represented by two different FEN strings, as detailed in the "COMMENTS" section here. In particular, the two FENs below are the same position, such that FEN alone cannot be used (e.g. with hashing) for counting unique positions. Possibly this should be mentioned in the article, and the word "particular" in the opening paragraph reconsidered?
rnb1kbnr/pppp1p1p/4pq2/5Pp1/8/8/PPPPPKPP/RNBQ1BNR w kq g6 0 1
rnb1kbnr/pppp1p1p/4pq2/5Pp1/8/8/PPPPPKPP/RNBQ1BNR w kq - 0 1
--Jientho (talk) 20:15, 23 December 2013 (UTC)
replies: text: It sometimes has to be specific. When it doesn't have to be specific, there is no reason for it to be specific. Also, you seem confused what a position is: if an en passant capture is possible in one position but not the other, then they cannot possibly be the same position. ISaveNewspapers (talk) 05:01, 15 May 2022 (UTC)
thread_title:  FEN overspecifies 

message: A recent edit has changed c5 to c6 in error. As the move was changed, but the FEN not, the FEN example became invalid. When I looked at the article, I was not aware of such a recent change, and adapted the FEN to be correct with c6. Also as such, I assumed the article has low attention, so made a few small corrections, which are not relevant. The change to c6 is clearly in error, it was not intended to introduce the move c6, the author assumed wrongly that the move meant is c6. As such I will roll-back my changes and this commit. I will do this edit by edit, this is just to document. Dlbbld (talk) 14:14, 20 July 2020 (UTC)
replies: text: Performed as mentioned, in one edit. Dlbbld (talk) 23:07, 20 July 2020 (UTC)
thread_title:  Erroneous change "c5" to "c6" invalidated FEN 

message: This article mentions halfmoves, saying they're relevant to the fifty minute rule and linking to that page, but doesn't elaborate. The fifty minute rule article does not mention halfmoves. There is no other content related to halfmoves on Wikipedia.
I therefore suggest that this article requires an explanation of what halfmoves are. Anyone care to write something up? Birdsinthewindow (talk) 01:36, 13 January 2023 (UTC)
thread_title:  Halfmoves?