Analysis of information sources in references of the Wikipedia article "Threefold repetition" in English language version.
By recurrence of position when the same position occurs three times in the game, and the same person is Player on each occasion, and if such Player claim the draw before the position is altered by further play, otherwise no claim can be sustained.
The position is considered the same if pieces of the same kind and colour occupy the same squares and if the possible moves of all the pieces are the same.
The position is considered the same if pieces of the same kind and colour occupy the same squares and if the possible moves of all the pieces are the same, including the right to castle or to take a pawn en passant.
