Chess (#1034)

Carlsen's rating peak has focused attention on calculation methodology. Ratings have inflated since the launch in 1970. How much? The answers are guesswork. Professor Elo's formula has proved fairly accurate over time and the base assumptions he made are simple.

But as the pool of rated players has grown, the collective ratings of top players have risen. There are more rated players now than ever before and the numbers are growing because the game is either officially sanctioned or encouraged in many national school systems. Each debutant introduces new approximations and the rating gains made by debutants aren't zero-sum.

One could contend, average ratings have also risen because the average player is stronger. The top 100 of 2013 are clearly stronger than the top 100 of 1973. One can prove this by examining middlegames and endgames with computer analysis for error frequency.

But while there is rating inflation, the difference between ratings has not inflated. Rating difference expresses the expectancy of scores. Somebody who scores 55 per cent against a 2200 player is rated at 2300. Somebody who scores 66 per cent is rated 2400; 75 per cent equates to 2500, etc. (These are approximations).

So rating differential may be a better measure of dominance. Carlsen at 2872 is 62 points ahead of Kramnik (2810) and Aronian (2809), just behind. The biggest difference was 125 points between Fischer (2785) and Boris Spassky (2660) in 1972. Kasparov (2851) was ahead of Anand (2769) by a larger margin in 2000. There's likely to be more work on this front since there are several maths and stats mavens trying to improve the system.

Meanwhile the Zurich Classic has seen a sequence of exciting draws in a round robin involving Kramnik, Caruana, Anand and Gelfand. The Italian GM leads — he won the sole decisive encounter so far, beating Anand in a good game. The most exciting games have involved Kramnik who has come within an ace of beating Caruana and Gelfand tactically.

In the Reykjavik Open, Wei Yi has become the youngest GM in the world at present at 13 years, 8 months and 23 days. Of course, Karjakin (12 years 7 months), Negi (13, 4, 22) and Carlsen (13, 4, 27) did it when they were even younger. Eljanov, So and Bassem Amin shared top spot with 8 points each from 10 games.

The DIAGRAM, WHITE TO PLAY (Gretarsson,Hjorvar Steinn Vs Navara,David Reykjavik 2013) leads to a spectacular finale. Why shouldn't white play 17.Bxh5? Due to 17...Rxb2! 18.Qd1. Qa5 19.Rc1 Nxe4 20.0-0 Nxc3 21.Qe1 Qxh5 22.Qxc3. I wonder how early Navara saw 22...Rxg2+! 23.Kxg2 Bxh3+ (0-1). Simplification leads to 24. Kf2 Bxf1 25. Rxf1 c5!

Devangshu Datta is an internationally rated chess and correspondence chess player