Friday, June 08, 2012

Memento V

We have come to the end of the Memento series, by which I mean we've reached the beginning.

Memento asked whether Black could allow White to force a king and pawn ending by playing ... Re1. As was quickly pointed out by one anonymous reader (or would have been had I not cut that comment) the position was taken from a Piket-Kasparov game played on the internet at the turn of the century and Gazza's attempt to keep the rooks on with ... Ra2 instead was the subject of Memento II.

If Kasparov had played ... Ra3 instead of ... Re1 a couple of moves earlier we'd have reached Memento III if White had played Rc7 in response. Well, almost. If you look closely you'll see the rook was on a2 not a3 in the position given there.

Memento III was taken from a game that Michael Stean and Bill Hartston played at the British Championship in Brighton more than a quarter of a century before Piket and Kasparov duked it out on the internet. Two almost identical endings played twenty years apart. Actually the position of Piket-Kasparov at move 46 is exactly the same as Stean-Hartston at move 41. This is, not coincidentally, where Memento started.

Memento III could have come from either game - it not making the slightest difference whether Black's rook is on the second or third rank. Memento IV, however, could only arise in Stean - Hartston. Piket's rook was on c2 for a long time so Gazza never had to decide whether or not to try to snatch the pawn on h2.

So we started off at move 46 of a game played in 1999 and after we wound back a few moves we ended up at move 37 of a game played in 1972. What are the chances, I wonder? What are the odds of two entirely different games reaching an identical position so late on? Does anybody know of any other examples of this happening?


Richard James said...

S Ionov - V Karasev Leningrad Ch 1983 reached Memento I with Black to play. He played Re4, and White played the winning move e6, just as Stean had done.

G Sarakauskas - M Bluvstein Budapest FS11 reached Memento I with colours reversed (Black having the extra pawn) and White to play. White went Re6 but Black failed to find e3, playing Ra2 instead. The game continued for another 37 moves before reaching a draw with rook and pawn against rook.

Y Schvayger - A Shankovsky Kiev Independence Cup 2009 again reached Memento I, this time with White to play. White failed to find e6, preferring h3 (after which e6 no longer works) followed by g4. She could only draw with king and pawn against king 12 moves later.

E Schiendorfer - V Kriste Swiss Ch 2011 yet again reached Memento I with White to move. Again White failed to play e6: the game continued 51. Ra7 Re3 52. Rb7 Re2 53. Re7 (now they've reached Memento I with Black to move) 53... Ra2, the position where Piket won with f5 against Kasparov. For the second time White missed the win, the game continuing 54. h3 Ra3 and only now 55. f5 which is a move too late and led to a draw.

Tom Chivers said...

How curious! A question for Tim Krabbé maybe?

Anonymous said...

There's actually a third game that reached your first position.

In endings, it cannot be that uncommon to reach the same position. If anything it's a surprise that you don't see more of them. If you were to just search the pawn structure h2,g3,f4,e5 against f7,g6,h5 with a Rook and King anywhere, you might find dozens. I've located thirty using an obsolete set of data.

Many of them are drawn. In the interests of stating the obvious, allowing the white King to reach h4/g5 isn't good for your drawing chances. So Hartston was a tempo short of a drawing position, which was forcing play by Stean.

Jonathan B said...

If you were to just search the pawn structure h2,g3,f4,e5 against f7,g6,h5 with a Rook and King anywhere, you might find dozens

Well yes, but *exactly* the same position is a rather different thing, isn't it?

Thanks to anony and Richard for pointing out that there are indeed more examples.

Anonymous said...

Regarding the pawn structure.

The best winning chances for white would seem to arise with the white king on g5 and the white rook on something 7, probably e7. So the black king will be on g7 or e7 if that square can be held. That just leaves the black rook looking for a square. If it's a position that white will aim for in search of a win, you are likely to get several examples.