Wikipedia:Reference desk/Archives/Computing/2019 November 7

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November 7

Standard chess notation for nonstandard starting positions

Does any de facto standard exist for extending algebraic notation so that games of chess that start with a nonstandard position (such as Chess960 and historical games played with the handicap of a missing piece) can be replayed and analyzed? NeonMerlin 03:36, 7 November 2019 (UTC)

First you would need to record the starting positions, which would require as many notations as pieces on the board. You could use codes like A1-bB for "square A1 contains black player bishop". Then, each turn could simply use the from and destination squares, like A1>B2 or A1xB2 (for the piece on A1 takes the piece on B2). This wouldn't be as easy to read directly, without moving pieces around on the board, but it would get the job done. The algebraic notation wouldn't be as reliable, say if the "queens bishop" may be one of 2 (or even 3) bishops starting on the queens side. Additional notations could be made for check, castling (if allowed), en passant pawn capture (if allowed), promotions (if allowed), and draws/stalemate/mate. SinisterLefty (talk) 03:47, 7 November 2019 (UTC)

OK, I will bite. SinisterLefty, when you have to use that amount of conditionals in your "answer", it usually means you make too much speculation for too little information, and should refrain from posting altogether.

Your post re-discovers long algebraic notation but with different symbols (it's "a1-b2", not "A1>B2"), and incorrectly says "queen's bishop" is part of algebraic notation (it is not: that would be descriptive notation, and even so, you could still use the existing square names even if it is a bishop that starts on Queen's Knight 1). As for "additional notations could be made..." - yes, they are already made, and the same are the in use in Chess960.

Notice that gadfium's answer below, although shorter by a factor of 5 or so, is correct and answers the question (which was "is there a standard", not "how would I go about designing a standard"). Tigraan^{Click here to contact me} 09:59, 7 November 2019 (UTC)

I've stricken most of my answer (although I stand by my assertion that you need one notation for the starting position and another for each subsequent move). As for gadfiums, it's good as far as it goes, but it doesn't say what to do after the starting position is noted. You obviously can't just denote the current board position in that way, as that wouldn't allow replaying the game, up to that point, because there are many ways a given board position could have been achieved. I suppose that notation (actually you'd need a modified version, X-FEN) could be used for both the initial position and every move made, but that would be both inefficient and ugly, if anybody has to look at it all. So, some notation for each move is also needed. The answer by 173.228.123.207 addresses some of this. SinisterLefty (talk) 13:34, 7 November 2019 (UTC)

Forsyth–Edwards Notation (FEN) is the standard notation for recording a board position.-gadfium 05:53, 7 November 2019 (UTC)

...and Portable Game Notation (PGN), which codes moves, can include a FEN indication for the starting position. Tigraan^{Click here to contact me} 12:51, 8 November 2019 (UTC)

For chess960, Fischer_Random_Chess#Coding_games_and_positions discusses notation. 173.228.123.207 (talk) 11:22, 7 November 2019 (UTC)