FIDE rules section 9.2 says:

Positions are considered the same if and only if the same player has the move, pieces of the same kind and colour occupy the same squares and the possible moves of all the pieces of both players are the same. Thus positions are not the same if:

  1. at the start of the sequence a pawn could have been captured en passant.
  2. a king or rook had castling rights, but forfeited these after moving. The castling rights are lost only after the king or rook is moved.

My question is about the correct interpretation of "possible moves" in regards to castling and en-passant rights. Has FIDE ever officially clarified this rule, or is there a petition out there somewhere for them to clarify this rule, to decide between these alternatives?

  1. It matters only what moves can actually be made from the positions in question. (Literally, the "possible moves" for the positions.)
  2. Both the moves that can be made, and the retention of rights to castle and capture en passant, must be considered and must match exactly between the positions in question.

I have two examples to illustrate the question.

First, castling rights. In this example, assuming both the king and rook have never been moved at the starting position, there is no possible future where White can castle. So is the final position in this example a threefold repetition or not?

[Title "White to Move"]
[FEN "4k1n1/8/8/8/8/8/4p3/2B1K2R w K - 0 1"]

1. Rh2 Nh6 2. Rh1 Ng8 3. Rh2 Nh6 4. Rh1 Ng8

Second, capture en passant rights. In this example, the white pawn can theoretically be captured en passant, but the only black pawn that could do it is pinned. So is the final position in this example a threefold repetition or not?

[Title "White to Move"]
[FEN "2k3n1/8/8/8/2p5/8/3P4/2R1K3 w - - 0 1"]

1. d4 Nh6 2. Kd1 Ng8 3. Ke1 Nh6 4. Kd1 Ng8 5. Ke1

In both examples, it depends how the phrase "possible moves" in the rule is defined. Has FIDE ever clarified this rule as it concerns cases like these?

closed as too broad by Brian Towers, Phonon, Herb Wolfe, Glorfindel, David Richerby Nov 25 at 17:07

Please edit the question to limit it to a specific problem with enough detail to identify an adequate answer. Avoid asking multiple distinct questions at once. See the How to Ask page for help clarifying this question. If this question can be reworded to fit the rules in the help center, please edit the question.

  • 1
    You ask several questions, some of which you acknowledge have already been answered and some of which you answer. You need to comment/answer on other questions you have issues with rather than start a new question. You also need to use questions for just one question at a time and not use them for raising discussion points. – Brian Towers Nov 22 at 12:38
  • I guess I can cut down on the length. The core of my question is the bolded part, which I think is not duplicate, though similar to these others. I wanted to pre-empt comments linking to these others, thinking I had not seen them already. – wberry Nov 23 at 18:08
  • @BrianTowers I have substantially edited the question and I hope it can be reopened now. Thanks! – wberry Dec 6 at 15:43
  • Thanks @Evargalo for the excellent example. – wberry Dec 7 at 15:54

This is not an answer, but a comment to show an example of a case where the OP's concern applies. I post it as an answer in order to include a diagram. @wberry, correct me if this is not the kind of position you were talking about.

  [Event "?"]
[Site "?"]
[Date "????.??.??"]
[Round "?"]
[White "White to Move"]
[Black ""]
[Result "1/2-1/2"]
[SetUp "1"]
[FEN "4k1n1/8/8/8/8/8/4p3/2B1K2R w - - 0 1"]
[PlyCount "0"]

Neither the white king nor the white rook have previously moved.

The game goes 1.Rh2 Ne7 2.Rh1 Ng8 3.Rh2 Ne7 4.Rh1 Ng8 : Is this a threefold repetition ?

Formally, White has lost his castling right. However, even in the starting position, there was no possible legal continuation of the game where White could castle (he cannot get rid of bPe2 without moving king or rook), so even if the formal right to castle has been lost, the possibility of a later castle has not been altered by the moved played.

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    This should be an edit to the question or a new question, but not an answer. – David Richerby Nov 22 at 18:05
  • Feel free to edit my question instead, you have the rep and it won't hurt my feelings :-) – wberry Nov 23 at 18:09
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    And yes this is what I'm asking about. This is actually a stronger case than I had in mind, because even in the starting scenario, no choice of moves permits a white castling later on. – wberry Nov 23 at 18:10

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