El reto de Nihal: la solución

22/05/2020 – El lunes pasado publicamos un problema de ajedrez planteado por el joven gran maestro indio Nihal Sarin. Se trataba de una posición muy complicada y compleja. ¿Estaría justificado el tentador sacrificio la dama que nos saltó a la vista inmediatamente? ¿Serviría para ganar o para simplemente poder mantener las tablas? ¿O incluso era un error muy grave y conduciría a una derrota? Sagar Shah, el editor jefe de ChessBase India, ha analizado la partida, con la asistencia del público. (En inglés.)

Komodo Chess 14 Komodo Chess 14

El año pasado, Komodo se proclamó Campeón del Mundo de Ajedrez en dos ocasiones. Es el “2019 World Computer Chess Champion“ y “2019 World Chess Software Champion“. La nueva versión, el Komodo 14 es todavía más novedosa y ha sido perfeccionado.

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Here is the position we gave you to analyse. It is quite challenging.

 

As you know you can move pieces on the above board to analyse.

The first thing you notice here is that Black is two pieces up – he has the two extra bishops – but the black king is in trouble. White can play 1.fxg7, which seems pretty good: if you take the pawn then there is 2.h6, and when the bishop moves you have 3.Qh5 with the threat of Ng5+, and this is very strong. Maybe Black's best defence, after 1.fxg7 is ...Be7, and the game goes on.

However, let's take a look at 1.Qg6, which is clearly very interesting. If the king moves to f8 or g8, because Ng5 comes with great force – it actually leads to mate. So Black must take the queen, and then 2.Ng5+ (if you play 2.hxg6++, then after 2...Kxg6 it looks like Black is completely fine) when 2...Kh8/g8 again result in mate (after 3.hxg6).

But Black plays 2...Kh6 after which 3.Nf7+ Kh7 is pretty much forced. So that would continue 4.Ng5+ and repetition. But wait a sec, White can try to win! How about 4.hxg6++ Kxg6 5.Nh8+ Kg5 (the only flight square available to the black king). Now you can think about a lot of interesting checks, like 6.Rh5+ or 6.Nf7+, until you hit on 6.Rd4, after which White is winning. Or is he?

And here is IM Sagar Shah discussing it in detail – and explaining why it is called the "Nihal Challenge".

You can stop at any stage and do your own analysis, right here on the board (here's a comprehensive tutorial on how to get the most out of the game viewer). One big advantage is that you can start an engine (fan icon) that will help you to analyse. You can get multiple lines of analysis by clicking the + button to the right of the engine analysis window. The "!" key, incidentally, shows you the threat in any position, which is incredibly useful in the case of unclear moves.

[Event "Is the queen sac on g6 justiified?"] [Site "?"] [Date "2020.04.12"] [Round "?"] [White "The Nihal Challenge"] [Black "White to play"] [Result "*"] [Annotator "Sagar Shah"] [SetUp "1"] [FEN "r1r2b2/n4ppk/p3pP2/qb1pP1QP/1p4P1/1P3N2/P1P5/1K1R3R w - - 0 1"] [PlyCount "33"] [EventDate "2020.??.??"] [SourceVersionDate "2020.04.12"] {[#]} 1. Qg6+ $1 (1. fxg7 $1 Bxg7 (1... Be7 2. g8=Q+ $1 (2. Qxe7 $6 Qc7 $11)) 2. h6 Bh8 3. Qh5 $18) 1... fxg6 (1... Kg8 2. Ng5 fxg6 3. f7+ Kh8 4. hxg6#) ( 1... Kh8 2. Ng5 fxg6 3. hxg6+ Kg8 4. f7#) 2. Ng5+ (2. hxg6+ Kxg6 $19) 2... Kh6 (2... Kg8 3. f7+ Kh8 4. hxg6#) (2... Kh8 3. hxg6+ Kg8 4. f7#) 3. Nf7+ Kh7 4. hxg6+ Kxg6 (4... Kg8 5. Rh8#) 5. Nh8+ $1 {Playing for a win!} Kg5 6. Rd4 $1 { A silent move protecting g4 and threatening Rh5#} Qxa2+ $1 {Never say never!} ( 6... Be8 {The Bishop drops back to help its monarch...} 7. f7 $1 {... but not for long! Now Rh5 is unstoppable} Bxf7 (7... g6 8. fxe8=Q Rxe8 9. Nf7#) 8. Nxf7+ Kg6 9. Nh8+ Kg5 10. Rh5#) (6... g6 7. Nf7#) 7. Kxa2 (7. Kc1 Qxc2#) 7... Rxc2+ 8. Kb1 ({You have to be very careful.} 8. Ka1 $2 Rc1+ $1 9. Rxc1 gxf6 $19 ) 8... Rh2 $3 {The double exclamation is not really for how good the move is, but for appreciating the resources that exist in the position.} (8... Rc1+ 9. Kxc1) 9. Rxh2 Bd3+ $1 10. Rxd3 {We reach a position where it is important for Black to decide what to do. He has this move and must make good use of it because otherwise White will put his rook back on d4 and threaten Rh5 mate.} ( 10. Kb2 Bg6 $19) 10... gxf6 (10... Nb5 $5 {Stopping Rd4.} 11. Rg3 $1 Kf4 (11... gxf6 12. Rg1 fxe5 13. Rh5+ Kf4 (13... Kf6 14. Rf1+ Ke7 (14... Kg7 15. Rg5+ Kh7 16. Rh1+ Bh6 17. Rg6 $18) 15. Ng6+ $18) 14. Ng6+ Ke3 15. Rh8 $18) 12. Rg1 Bc5 13. Rgh1 Nc3+ 14. Kc2 gxf6 15. exf6 Rc8 16. f7 $18 {And although the position looks complex, objectively White is winning.}) (10... Rc8 11. Rd4 $18 {with a forced mate.}) (10... Kf4 11. Nf7 gxf6 12. exf6 Nb5 13. g5 $18) (10... Nc6 11. Rd1 Nxe5 (11... gxf6 12. exf6 Kxf6 13. Rh7 $18) 12. Rh5+ Kxf6 13. Rf1+ $18) ( 10... Z0 11. Rd4) 11. Rd4 $1 (11. Rf3 $1 {is also strong.} Bg7 12. Nf7+ Kg6 13. exf6 Bxf6 14. Rh6+ $18) 11... fxe5 12. Rh5+ Kf6 13. Rd1 Bc5 (13... Ke7 14. Ng6+ Kd6 15. Rh8 Nb5 16. Kb2 Ra7 17. Rxf8 $18) 14. Rf1+ Ke7 15. Rh7+ Kd6 16. Nf7+ Kc6 17. Nxe5+ $18 {The entire analysis is not exhaustive, but you get a feel of how White should be better in all these lines. In any case, what I love about the position is that first White sacrifices his queen to get at the black king, and then Black strikes back to defend! A beautiful example of attack and defence and a big thanks to Nihal for sharing the solution with us.} *

There is one more thing you can do. It is a lot of fun, but also a serious challenge: Click on the rook icon below the notation window. This will allow you the play the above position against Fritz, at your level of playing strength (e.g. "Club Player"), right here on the news page. Note that your analysis, in which you can delete, move or promote lines, is stored in the notation as new variations. In the end you will find the game with your analysis in the cloud. So nothing is ever lost.

Please tell us what you think of this analysis. Do you agree, can you poke holes into it?