Puzzle of the week #20

Chess Diagram: 

[Event "Puzzle #20"][Date "2008.05.15"][Result "1-0"][SetUp "1"][FEN "5qbk/p6p/1rp2p2/2pp4/2P2Q1N/1P6/P4PPP/4R1K1 w - - 0 27"]

It is always a pleasure reading articles by Susan Polgar, or her online blog. She always has interesting opinions and advises, plus great chess material coverage for various chess events from the local stage, to the international scene. This week I had the chance to read her original article "A major boost for SPICE" posted at ChessCafe.com, where she mentions between other chess events the European Individual Chess Championship 2008 from Bulgaria. She annotates one game of the newest crowded European Woman Champion, WGM Katerina Lahno (Ukraine). The game is K. Lahno (2479) - K. Nemcova (2344), where after 26... Bg8 they reached the following position (see diagram). Your tasks:
a) White to move and win. The line is 7 moves long at it is worth 7 points
b) What tactical element is White using to win? (1 point)
c) What strategical element is White using as an important part of the winning plan? (1 point)

Total available points for this puzzle is 9 (7+1+1). The answers will be published next week together with puzzle #21.

Puzzle #19 solution:
This time the solution needed clear answers and precise calculations. It was meant to be a small test for everyone on how they look at a position, the conclusions they reach and solutions they come up with based on it. The first thing to notice is Black having 3 undeveloped pieces (Ra8, Bc8 and Rh8), reason why White's attack is successful and answer to question "d". Any undeveloped/ blocked piece unable to defend in case of an attack values nothing! We can also see that Kg8 is trapped and each Black Knight defends a possible mate on "g5" and/or "e8". Now we begin sensing there's something going on here and the obvious choice is to attack the defenders Nf6 and Ne4; removing them (answer to question "b") would end the game. The easiest one to attack is Ne4 and all we need to decide is how. See solution below.

[Event "Puzzle #19"][Date "2008.05.08"][Result "1-0"]1.e4 e5 2.Nf3 Nc6 3.Bc4 Bc5 4.c3 Nf6 5.d4 exd4 6.cxd4 Bb4+ 7.Nc3 Nxe4 8.O-O Bxc3 9.d5 Ne5 10.bxc3 Nxc4 11.Qd4 Ncd6 12.Qxg7 Qf6 13.Qxf6 Nxf6 14.Re1+ Kf8 (14...Kd8 15.Bg5 Ne8 16.Rxe8+ Kxe8 17.Re1+ Kf8 18.Bh6+ Kg8 19.Re5 {White wins}) 15.Bh6+ Kg8 16.Re5 Nde4 17.Nd2! {The threat is 18.Nxe4 Nxe4 19.Re8#} 17...d6 (17...Nxd2?? 18.Rg5#) 18.Nxe4 dxe5 19.Nxf6#

Correct solutions:
Jacob, Jeremy, Algerd, Wilson, Katerina and Nathaniel - 8 points
Matthew - 7 points
John D - 5 points
Joanne, Ning Ning and Tse Hoi - 4 points
Karl - 3 points

67.0 John D
64.0 Jeremy and Jacob
49.0 Matthew
41.5 Katerina
31.5 Karl
29.5 Joanne
24.0 Wilson
20.5 Algerd
17.5 Frank
16 more solvers with less points

Congratulations to everyone presenting solutions! This must be some sort of a record result with so many solving all or part of it.


Distracting the defender