10 June 2011

What's cooking?

Hopefully you're not too disappointed that I'm not gonna write about culinary goodies. My writing is still about chess problems. Nevertheless, I want to mention cooks — a contradiction? Only, if I intended to mention those guys preparing delicious food in the kitchen. — Problem chess and cooks? Where's the link?

In simple terms a cook is a flaw in a chess problem. This might be an unintended (additional) solution or a possible defense was overlooked by the composer, so that there is no solution at all. Thirdly, the solution may not be unique due to so-called duals. Of course, all thes possibilities spoil a problem.

It's not absolutely clear, where this term cook comes from. The general opinion is that it's named after the nineteenth-century problemist Eugene Beauharnais Cook (1830-1915) who was famous for a phenomenal solving talent. Emanuel Lasker came up with this explanation. On the other hand, the problemist Benjamin Glover Laws (1861-1931) traces the term back to a statement of Josef Kling. Moreover, I've read that cook is probably derived from the word's English slang meaning (to tamper with or foil).

Anyway, cooks are so annoying! And this leads us back to the endgame studies. There are very strong solving programs with which you can check a great varity of chess problems. But what to do with those studies? Sure, you can use powerful chess engines and query endgame tablebases. But there is no general foolproof method to check a study for correctness. How to spot the best moves and defenses? At which point can the composer (in the previous post, it was the solver to ask) say "and wins" or "and draws" without doubt, unless a tablebase position or a book draw/win (stalemate, insufficient material, a forced mate in x, etc.) is reached? You and/or your engines might still miss a critical move, possibly exactly the one that spoils it all.

Guess what? When writing last week's post, at first, I had selected a cooked study. I only noticed when I compared the given solution in a book with the one in Harold van der Heijden's endgame study database. So, cooked chess problems are also irritating for authors like blog writers! Grrrrrr. Anyway, I do my best to pick only sound studies for you.

By the way, in his book Studies and Games, Jan Timman shows several of his compositions with all the flaws they have/had – e.g. anticipations, duals, being unsolvable. It's very interesting to read about the backgrounds of his works and how he managed to repair or further develop the cooked problems. I think it's quite rare that a composer writes so much about his unsuccessful attempts. Kudos to GM Timman!

In 2007, there was an international composing tournament with the thematic task "Studies for Practical Players". It was held in recognition of Mark Dvoretsky's 60th birthday. Obviously, most composers were making active use of computer programs and of endgame tablebases. Nevertheless, there were also 21 cooked problems! Here are some of the prize winners for you to enjoy:

N. Rezvov
S. Tkachenko
Dvoretsky-60 JT, 2007
1st Prize
1. Bf6!
Not 1. Nxe6?, as after 1. - b2 2. Bg5+ Kf2, White would have to give up the bishop for the pawn: 3. Be4 b1=Q 4. Bxb1 Nxb1.
1. - b2!
Weaker is 1. - Nxc5+? 2. Kxa3 +-
2. Bxb2 Nc4
This gets the knight away from attack with gain of time.
Again, 2. - Nxc5+ 3. Kxa3 is lost.
Now, where should the bishop go?
3. Bh8!!
Tempo play does not work: 3. Bc1+? Kf2! 4. Bd5 Nxc5+ 5. Kb5 Nd3 and the knights will reunite on the next move.
Also, 3. Ba1? Nxc5+ 4. Kb4 Nd2,a5 only turns out to be in favour of Black.
3. - Kf2!
Black has all the time to harrass the bishop. The knight on c5 can wait, it's not going anywhere.
4. Bh1!!
This move to the corner drives the black king further away.
The premature 4. Ba8?! analogous to the previous move fails: 4. - Nxc5+ 5. Kb5 Nd7! 6. Bd4+ Ne3! 7. Be4 Nf8! 8. Kc6 Ne6.
4. Bh3? Nxc5+ 5. Kb4 Kg3! also does not win.
4. - Kg1!
4. - Nxc5+ 5. Kb5 Ne3 6. Kxc5 Ng2 7. Bd4+! and the (temporarily) trapped bishop is save. The two bishops win versus the knight.
5. Ba8!! Nxc5+
5. - Nb6+ 6. Ka,b5 Nxa8 7. Nxe6 +-
6. Kb5! Nd7 7. Bd4+! and wins. Now, there is no Ne3 that saved Black before with his king on f2.

Three times, the bishops have to hide in the corners in their battle against the knights that goes on across the whole board.

Y. Bazlov
Dvoretsky-60 JT, 2007
2nd Prize
Apparently, this position is clearly better for Black, isn't it? It seems quite probable that sooner or later that game is lost for White. But, unlike in an OTB situation, we do know that there is a way to save this!
First question: Where to put the rook? 1. Rd2? Qh6+ 2. Nh3 Qxd2+ or 1. Rd3? Qf2+ 2. Kh3 Qf5+ fails immediately.

1. Rf1! Qb2+
1. - Qh6+ is not dangerous: 2. Nh3 Qd6 (2. - Ne4 3. Ng4) 3. Rf5 Qe6 4. Rh5 Ne4 5. Nf4 Qa2+ 6. Ng2=.
2. Kh3
Of course not 2. Kg3? Ne2+.
2. - Qe2 3. Rf5
Though everthing is protected, White is still not out of the woods yet.
3. - Qh5+ 4. Kg2
4. Kg3? Ne2+ 5. Kg2 Nd4 6. Ne4 Qe2+ and one of the white pieces will be captured.
4. - Nd5
4. - Ne4? is weak, for the rook is indirectly protected: 5. Nxe4 Qxf5 6. Nd6+. Now, how to neutralize the threat Ne3+?
5. Kg3!
The knights can't move. 5. Ne4? is not the same as before: 5. - Ne3+ 6. Kg1 (otherwise the rook is captured with check) Qd1+ followed by 7. - Nxf5. Also, 5. Nd7? Qg4+ is clearly lost.
5. - Ne7 6. Ng4!!
White sacrifices the rook without obvious compensation. But he has to, there is nothing else: 6. Kf4? Qh2+ (6. - Nxf5? 7. Kxf5=) 7. Kg4 (7. Ke4 Qc2+) 7. - Qg2+ 8.Kf4 Nd5# Oops, a mate in the middle of the board!
Okay, White threats the fork on f6. But Black comes first and captures with check.
6. - Nxf5+ 7. Kf4 Qg6 8. Ne5 Qf6 9. Ng4
The last stumbling block is 9. Ne4? Qe6 10. Ng5 Qc8 and Black wins. The black queen has not many squares from where it can both protect the knight and avoid a fork.
9. - Qf8 10. Ne6 Qf7 11. Ng5 Qg6 12. Ne5 and draws. Black can't escape from the continuous attack.

S. Didukh
Dvoretsky-60 JT, 2007
3rd Prize
1. Nh5!
Insufficient tries:
1. Rh1? Kxg7! (but not 1. - Nf2? 2. Rh2 Kxg7 3. Kc7) 2. Rxh3 Nd6+! 3. Kd7 Nf5 4. Rd3 Kf6 and Black has built a fortress.
1. Ne8? e5+ 2. Kd8 exd4 3. Rh1 Ng5=; according to the tablebases, 3. Rd1 Kh7 4.Rxd4 is a drawn position.
1. - e5+!
1. - Kg8 2. Kd8 leaves Black no chance at all: White gradually realizes the advantage of the exchange by purely technical means. For example: 2. - Kf7 3. Ra7+ Kf8 4. Ra3 Bg4 5. Re3 Nd6 6. Ng3 Nc4 7. Re1 Kf7 8. Kc7 Kf6 9. Ne4+ Ke7 10. Nc5 Kf7 11. Nd7 Bf5 12. Ne5+.

Now, White has a difficult choice: where to go with the king? It seems reasonable to let it approach the black pawn: 2. Kc7? exd4 3. Rh1 Bg2 4. Rh4 Kg8 5. Rg4+ Kh7! 6. Rxg2 d3 7. Rg1 d2 8. Rd1 Kg6 9. Nf4+ Kf5 10. Nd3 Kg4 11. Rf1 Nc3 12. Nb2 Nd5+!! 13. Kd6 Ne3, draw!
A different check will spoil things with the king on d8: 2. Kd8? exd4 3. Rh1 d3! 4. Rxh3 Nf2 5. Rg3 d2 6. Nf6 and the black pawn promotes with check! Therefore ...
2. Kb8!! exd4
2. - Bg4 3. Re1!
3. Rh1 Bg2
Now, the variation 3. - d3 4. Rxh3 Nf2 5. Rg3! d2 (5. - Kh7 6. Nf6+ Kh6 7. Ng4+!) 6. Nf6 d1=Q contains no check, so White continues with 7. Rg8#.
4. Rh4 Kg8 5. Rg4+

A) 5. - Kh7!
5. - Kf7?! 6. Rxg2 d3 7. Rg7+ Ke6 8. Nf4+ +-
6. Rxg2 d3 7. Rg1! d2 8. Rd1 Kg6 9. Nf4+ Kf5 10. Nd3! Kg4 11. Rf1! Nc3 12. Nb2 Kg3
Unfortunately, there is no longer enough time to bring the knight over.
13. Nd1! and wins.

B) 5. - Kf8 6. Rxg2 d3 7. Rg1 d2
7. - Nf2 (7. - Nc3 8. Rf1+! Ke7 9. Rf2) 8. Rf1 d2 9. Rxf2+
8. Rd1 Ke7 9. Nf4 Kd6 10. Nd3 Kd5
10. - Kc6 11. Ne5+
11. Nf2! Nxf2 12. Rxd2+ and wins.

Surely a difficult study. White wins a piece by force and is a rook up. But this advantage in material can't be converted with ease. The remaining pawn gives Black serious counterplay. Only the foresighted second move brings the win for White.

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