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:
- at the start of the sequence a pawn could have been captured en passant.
- 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?
- It matters only what moves can actually be made from the positions in question. (Literally, the "possible moves" for the positions.)
- 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
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 moves played.
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?