Single Comment

I have a couple questions concerning the three-fold repetition rule. The
official FIDE version of the rule is:

The game is drawn, upon a correct claim by the player having the move,
when the same position, for at least the third time (not necessarily by
sequential repetition of moves) 
(a) is about to appear, if he first writes his move on his scoresheet and
declares to the arbiter his intention to make this move, or 
(b) has just appeared, and the player claiming the draw has the move. 
Positions as in (a) and (b) are considered the same, 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. 
Positions are not the same if a pawn that could have been captured en
passant can no longer be captured or if the right to castle has been
changed temporarily or permanently.

My questions are on the last sentence. Consider this position:
W: Kc1 Nh1 Pc5
B: Kb8 Rc8 Nh8 Pd5
Black has just moved ...d5. The knights are then shuffled around,
resulting in the position repeating two more times. However, the rule
says
that 'positions are not the same if a pawn that could have been captured
en passant can no longer be captured.' In this case, the pawn cannot be
captured en passant in any of the three positions (the white pawn is
pinned). Are all three positions considered the same, even though the
right to capture the pawn en passant would have changed in the absence of
the pin?

My second question is about the 'right to castle' provision. Consider
this position:
W: Ke1 Ra1 Nb5
B: Kh4 Bf8
Suppose white's king and rook have not moved. The knight and bishop move
around, resulting in the position repeating two more times. However, in
doing so, the bishop checks the white king and is blocked by the knight.
Since the right to castle has been changed temporarily, are all three
positions the same?

Also, from that position, suppose that instead of white being checked,
white moves her knight between the king and rook. Since this temporarily
changes the right to castle, are all the positions the same?

Consider this position:
W: Ke1 Rh1 Bb2
B: Ka8 Ra7
From here, it is impossible for white to ever castle, even if his king
and
rook have not moved. Does it make a difference here if the right to
castle
is changed temporarily (e.g. the black rook checks the white king and is
blocked by the bishop)?