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Chessville
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In analysing this position I found some things that the Informant analyst (Tseitlin) either missed or did not think worthy of mention. At the risk of causing amusement to my higher-rated colleagues, I will try to describe the steps I went through in solving this position in the hopes that the more general reader will find it interesting and perhaps instructive. Two positional factors stand out immediately:
1.
Black's king is under pressure from White's active pieces; So what does White have? Because his queen hanging, it is obvious that he must act quickly. The first candidate moves that come to mind are 1.Qxc8, 1.Rxh6+ and 1.Nxh6. The first two can be dismissed right away. 1.Qxc8 Qxc8 obviously leads nowhere. If 1.Rxh6+ Black simply captures the rook with 1...Rxh6 and there is no follow-up since 2.Nxh6 fails to 2...Rxc3 3.bxc3 Kxh6 and White's queen has gone missing in action. How about 1.Nxh6? Black has to take the knight since 1...Rxc3 allows 2.Nxg8+ (check!) followed by 3.Rxc3 and White is up the exchange for no compensation, thus meeting the stipulation. However, there is nothing particularly unusual or aesthetic about this variation, so it is unlikely to be the reason for publishing the position in Informant. In fact the difficulty with 1.Nxh6 is 1...Rxh6. After 2.Rxh6+ Kxh6 3.Qh3+ or 3.Qf6+, White appears to have nothing more than perpetual check. Once his queen goes to the kingside he cannot strengthen his attack in any meaningful way due to the persistent threat of ...Rc1 mate. One thing that often makes an Informant combination special is a relatively quiet key move, in other words, a move that significantly improves the position but which does not capture or sacrifice material. Such a move is available here: 1.Qe3, saving the queen without allowing mate, and also increasing the pressure on h6. This looks quite promising; let's see if it stands up to analysis. A random move such as 2...a5 will be met by 2.Rxh6+ Rxh6 (forced) 3.Qxh6 mate, so Black has to react to this. How about 1...f4? The obvious reply is 2.Qd3+, and what does Black do then? If 2...Rf5 White mates immediately with 3.Rxh6, so that leaves only 2...Nf5. Unfortunately for Black, moving the knight from g7 sets up a discovered attack from White's rook on e7, and in fact White has the very strong continuation 3.Nxh6+, attacking Black's queen. Perhaps you are thinking, "What about the threat of ...Rc1+?" Well, it's a threat in name only, since there's no time for execution: Black is in check. Where to go with the king? 3...Kh8 is a total disaster after 4.Nxf5+. The queen must now interpose (with 4...Qh7), after which White takes with the e7-rook (5.Rexh7+) and then mates quickly after 5...Kg8 6.Rg7+ Kf8 7.Rh8 mate. Very nice. So 3...Kh8 doesn't work, but how about 3...Kg6? We can dismiss that pretty quickly as well. After the simple 4.Nxg8! Rc1+ 5.Qf1 Rxf1+ 6.Kxf1 Nxe7 7.Nxe7+ White ends up a piece ahead for almost nothing, again satisfying the stipulation. Is there anything else Black can do after 3.Nxh6+? 3...Rf7 is about all that's left, but it's a non-starter because of 4.Qxf5+, winning a cartload of material and then delivering a quick mate. So Black's goose appears to be well and truly cooked after 1.Qe3 f5 2.Qd3+. Is there any other defence available? Yes; Black can meet 1.Qe3 with 1...h5, trying to block the h-file, and also giving his king a bit of breathing room. But now that his queen is no longer attacked and the mate on c1 is defended, White can play 2.Nxd6. This move does two things: it attacks Black's rook, and it sets up a pin on Black's knight, which means Black's h-pawn is no longer defended. The threat now is 3.Rxh5+ Kg6 4.Qg5 mate, which is hard to meet. In fact, if Black moves his attacked rook anywhere but c1 with check (a pure suicide mission) White just executes the threat. This leaves Black very few options. He can vacate g8 with his queen and give his king a flight square, but after 2...Qd5 3.Nxc8 Qd1+ White has the simple defence 4.Qe1 since his queen is supported by the rook on e7. The only other try is the line-blocking 2...f4 but as before this allows 3.Qd3+ and regardless of Black's reply White captures the rook on c8 next move and wins on material, thus satisfying the stipulation. Well, the results of this analysis seem quite clear. The combination demonstrates the power of the key move 1.Qe3, which leaves Black tied up and unable to defend against White's attack. It is useful to develop an awareness of such methods since in practice they arise more often than one would think. After working through training books such as Fred Reinfeld's 1001 Winning Chess Sacrifices and Combinations it is easy to conclude that all decisive tactical operations must consist entirely of checks, captures and sacrifices, but many times that just isn't the case. So now it was time to turn to the solution as given in Informant. When I did that I got a bit of a surprise. There was no mention of the variations shown above. Tseitlin played 1.Nxh6, which was met as predicted by 1...Rxh6. But then instead of settling for perpetual check, he uncorked a deflection sacrifice with 2.Rxg7+! This diverts Black's queen and leads to the sequence 2...Qxg7 3.Qxc8. Now if Black captures with 3...Rxh3 White has the intermediate move 4.Qxf5+! recovering the rook and picking up a pawn as well. After 4...Kg8 the most accurate way is 5.Qe6+! either capturing the rook with check and using the tempo to defend his queenside, or exchanging queens after 5...Kf8 6.Qc8+ followed by 7.Qc7+ and then capturing the rook with an easily winning pawn ending (White uses both h-pawns as decoys and if necessary captures all of Black's remaining pawns.) In the game Black played the stronger 3...Qf7 instead of 3...Rxh3. After the further moves 4.Re3 Rg6 5.g3 he decided to throw in the towel. He is a pawn down and the weakness of his king's position means that simplification to a lost queen or rook ending is not far off. Is it meaningful to ask if one or the other solution is better? Both lead by force to winning positions for White. Frankly speaking, I did not take the stipulation to mean that White would settle for winning a mere pawn, and so I did not look past 1.Nxh6 Rxh6. On the other hand, despite the modest win of material, the associated simplification destroys all trace of hope for Black. At the master level this is the easiest of wins for White. I think I prefer my solution to that given by Tseitlin, but I'll leave it to the reader to form his or her own conclusions. Finally, what does Fritz have to say about these lines? Well, it immediately finds both my analysis and the game continuation; however, these are ranked second- and third-best respectively. According to our German friend, the strongest continuation for White is 1.Qd2! This looks like an improvement over 1.Qe3 because there is no hit on the queen after 1...f4. White does not have to play 2.Qd3+, but can sacrifice the knight in an improved situation with 2.Nxh6! Now 2...Rxh6 leads to a quick mate after 3.Qd3+ Kh8 4.Rxh6, while trying to make room for the king with 2...Qc4 leads to mate all the same after 3.Nf5+ Kg6 (or 3...Kg8 4.Rxg7+ Kf8 5.Rh8 mate) 4.Rxg7+ Kxf5 5.Rh5+ Ke6 6.Qe1+ Qe4 7.Qxe4. After 1.Qd2 h5 2.Nxd6 f4, White again does not have to move his queen, but instead can play 3.Rxh5+ Kg6, and now 4.Rh4! with two extra pawns and a very strong attack is considered best by Fritz. This attack is rated more highly than any of the winning lines that I discovered. The latter variation highlights some real differences between human analysis and computer analysis. A program such as Fritz is tactically perfect within a short range and will therefore prefer winning a rook after eight moves to winning a knight after three moves. I am sure that most strong human players would take the knight if it led to a clear-cut win. This is a practical decision because with every further move analysed on the mental chessboard, the possibility of error increases. Even after consulting Fritz, I still prefer my solution.
Here is another position from Chess Informant illustrating our theme.
White has two different ways to win, only one of which was found by the
analyst. Your task is to find both of them.
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