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

andrew buchanan andrew at anselan.com
Mon Feb 9 19:45:14 EST 2009

Dear Andrey,

> 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.

Yes of course in real life these cannot be claimed to be the same. But I was trying to salvage an interesting conceit from Jonathan's mail, of what I term "moral right" to claim a draw where the positions are not precisely the same. It's possibly not a fruitful idea, but I just thought it was novel.

For example:
After 1.Nb3 N~ 2.Na1 Nf6 3.Nc2 N~ 4.Nd4 Nf6.

The position now dominates the initial position and the identical position after 2 moves from each side. Since White's first and third moves were different, he cannot draw with his next move. But I claim that White has the "moral right" to claim a draw now, since his position dominates the earlier two similar 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.

This is true and interesting, but I was thinking about orthodox chess to keep this simple.

>> 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.

Yup. As I typed those lines, I was remembering a radio program from the weekend where Stephen Fry, a very entertaining British broadcaster, was talking about language and in particular quotations. He was taking the whimsical position that inaccurate or incomplete quotations were more sincere that complete ones, because they came from the heart, while complete quotations can just be looked up. Particularly, I feel, now that search engines make the world omniubiquitous. It was with that curious thought in mind that I decided not to look up the author.

>> 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.

I am not sure that it does. If the draw by 50 is optional, then DR wouldn't get a look in. So let's say that we have the conventions so draw by 50 is mandatory. Fine: but who's to say whether DR is "aware" of the conventions? But it seems to me that there are two possible worlds:
(a) DR is aware of the mandatory draw by 50, and factors that into all its thinking.
(b) DR is innocent of the mandatory draw by 50. Mandatory draw by 50 will come in like a deus ex machina without any anticipation.
Option (a) is probably more interesting, but that doesn't make it more likely to be correct.


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