Chess (#1159)

The Biel Super GM has been hard-fought. The six-player double-round-robin has seen 15 decisions in 27 games so far, as well as interesting draws.  Maxim Vachier-Lagrave and Radek Wojtaszek are tied for the lead with 5.5 each after 9 rounds. David Navara (5) is third, with Michael Adams and Pavel Eljanov (both 4.5) just behind. Richard Rapport (2) has taken a hammering.  

High decision ratios depend on format, prize money & appearance fee distribution, Elo differences and player-mindsets. Inviting players with ambitious mindsets helps as do rules that inhibit bloodless draws.  

A Swiss format can be "over-competitive". Typically, prize money is divided such that a half-point difference may mean massive differences in pay-off. Tiebreaks on the same points often depend on uncontrollable factors. So desperate risk taking is quite normal. Large Elo rating differences can also create peculiar dynamics if the lower-rated player tries to draw while the higher-rated one takes risks. 

The Biel Super invited players with positive mindsets. The ratings of the top five are very close, with Adams #1 at Elo 2740 and Eljanov #5 at 2723. Rapport (2671) is lower-rated. Draws offers are forbidden till move 40. There will be a playoff for the top spot if required. Everybody has lost at least once and Rapport is the only player without a win.   

The DIAGRAM, WHITE TO PLAY (White: Navara Vs Black: Wojtaszek, Biel 2015)  is an example of trust in engine analysis. White has gained 8 minutes at the diagram. On average, he's spent less than the increment of 30 seconds /move. Now 22.N5xe4 Ne5+ 23.Kf4 Ng6+ is a perpetual. 

But Navara instantly went 22.Kf4!? g5+ The engines say 22...Rd6!? is equal. Now play is forced with 23.Kf5 Rhe8 24.Rhd1 Re5+ 25.Kf6 Rg8 26.bxc4 Rg6+ 27.Kxf7 Re7+ 28.Kf8 Rf6+ The engines say there's no mate. One perpetual is 28...Reg7 29. N3xe4! Rg8+ 30. Kf7 Ne5+ 31. Ke7 Nc6+. The Nc5 guards e6, unlike in 29. N5xe4? Rg8+ 30. Kf7 Ne5+ 31. Ke7 R8g7+ 32. Ke8 Re6+ 33. Kf8 Rf7+ 34. Kg8 Re8# 

Black was in time trouble. The game went 29.Kg8 Rg6+ 30.Kh8! Rf6 31.Rf1 Bf2 32.Rxf2! Rxf2 33.Rf1 Rxg2? After 33...Re8+ 34.Kxh7 Rxg2 35.N3xe4 Re7+ 36.Kg6 b6 37. Nd6+ Kc7 38. Nf5 bxc5 39. Nxe7 Nxe7+ 40. Kxg5 white is better.  

But this loses to 34.Rf8+ Kc7 White missed a win with 35.N5xe4! Rxc2 36. Nd5+ Kd7 37. Nxg5+ Ke5 38. Nc8 (and Rf5#). A sharp rook endgame arose with 35.Nd5+? Kd6 36.Nxe7 Kxc5 37.Rf5+ Kxc4 38.Nxc6 bxc6 39.Rxg5 Rg3 White won after errors on both sides with 40.h4 h6 41.Rg6 Rxe3 42.Kg7 Rg3 43.Kxh6 e3 44.Kg5 Kd5 45.Kf4 Rh3?! 46.h5 c5 47.Rg5+ Kd4 48.Re5 (1-0) Re4+ will take the e-pawn.

Devangshu Datta is an internationally rated chess and correspondence chess player