[Retros] How many times could a Diagram be repeated during a proofgame?

[afretro]

Dear Andrew,
A very fast and selective response to your mail.

> So for example, if a position occurs 3 times 

> (White to Play) with WKa1, except the first time 

> there was also BQb1 present on the board, then 

> does White have the moral right to claim a draw? 

> After all, he now has all the moves and more that 

> were at his disposal the first time round.

With or without BQb1 – these are different positions. In some fairy types, e.g. Circe, castling rights CAN be restored. Two externally identical positions may appear one after another on the chessboard, differing in that e.g. white has lost the castling right in the first position and has regained it in the second.

> Indeed there is a famous problem by somebody where 

> White spends the first 4 double moves eliminating 

> Black's castling rights, returning twice to the 

> original diagram.

It was by Nenad Petrovic.

> We could argue that a position with 50 moves left is 

> different from one with 47 moves left is different from 

> one with 2 moves left...

Of course the Dead Reckoning rule can also come into play.
Yours,
Andrey