Alan Atkinson wrote:
The arbiter would have perhaps have had more abuse for being overly officious in pointing out that the position was going to need to go around once more, because it would then have just gone around once more, I suspect.
This is what John Saunders wrote in his round 9 report
http://iominternationalchess.com/news-m ... eport.html
*Re the repetition: it turns out it wasn't a strictly legal repetition under FIDE law 9.2. After 14...Nc2+, when the first of the three putative identical positions arose, the white king still had the legal right to castle later in the game. That was not the case after moves 16...Nc2+ or 18...Nc2+, therefore position 1 is not considered to be identical to positions 2 and 3 under the law. You can see that, legally, White could have made a capture on move 15 with 15.Qxc2 and the white king could later have castled but, interestingly, I have it on good authority that position 1 would still not have been considered identical to positions 2 and 3 even if, on move 15, the white king had no other option than to move, thus ruling out future castling anyway. Had the arbiter spotted this irregularity, the threefold repetition claim would have failed and the game continued (albeit only as far as the next move, when White could have claimed, or else for one further repetition by Black, assuming that the players were still minded to draw in this way).
There's a picture of the scoresheets as well
http://iominternationalchess.com/images ... 159589.jpg
The other way for Magnus to claim a draw would have been to write Ke2 as the 19th move, but without actually playing it.