Puzzle of the week #86

Chess Diagram: 

[Event "Puzzle #86"][Date "2009.09.18"][Result "1/2-1/2"][SetUp "1"][FEN "1R6/8/8/5k2/5p2/1p5r/4K3/8 b - - 0 1"]

The morning after the admission testing is always calm and sunny. It is good to play chess, isn't it? It is a bit like being a scientist working to discover a new theory that will bring a lot of good to people. He looks at what he knows over and over again, trying different ways to come up with new ideas the same way we look at our puzzles. Sometimes inspiration comes in the most unexpected way; for Archimedes (approx. 287 BC - 212 BC) - the famous Greek inventor - it once came while taking a bath. It is the moment forever remembered in history when he exclamed "Eureka!" meaning "I found it!" while running on the street naked.
Today puzzle might be one of those moments for you. It is the end of the game between 2 Grand Masters: Bronstein - Smislow, Groningen Holland 1946 Black is very much in control with his extra 2 pawns and winning the game seems just a matter of time. He decided to use the skewer and moved 1... b2 Your task:
a) Was this a good idea? Please provide a line showing how Black wins (if you think it was a good idea), or how White saves the game (if you think it was not a good idea)
b) Explain your solution

Total available points for this puzzle is 15. The answers will be published next week together with puzzle #87.

Puzzle #85 solution:
Surprisingly I did not get very good answers this time. The most important reason is everyone chose poor play for Black in his task to still save the game. If you are behind it is time to challenge yourself and come up with ideas and tricks; anyone can play when they are in front. Here is one partial good answer I got from James: James explanation:
b) White here is up a Knight and has a extra passed pawn and must try to promote it while Black will do his best to stop it. Winning is just around the corner for White and he should quickly finish the game.
Indeed White should focus on using the positional advantage on the Queen side to win the game. Once you have established this, coming up with the right moves (meaning best play for both sides) is not that hard. See solution:

[Event "Puzzle #85"][Date "2009.09.04"][Result "1-0"][SetUp "1"][FEN "8/2rb4/4k2p/P2p2p1/1N1Ppp2/7P/5PP1/1R3NK1 w - - 0 41"]41.Na6 {Game line} 41...Rc4 (41...Ra7 42.Nc5+ Kd6 43.a6 {Black's pieces (Rook and Bishop) will be blocked defending against the a6-pawn. Please note the position of "Nc5" on a dark square, something his Bishop cannot attack. Black is strategically lost here and winning it is rather easy}) 42.Nc5+ Kd6 43.a6 Rxd4?? 44.a7 Bc6 45.Rb6 Kxc5 46.Rxc6+ {White wins}

Correct solutions:
Andy Q - 15 points
Owen - 12 points
James - 10 points
Rick - 5 points

Andy Q - 160 points
Rick - 140 points
Jeremy - 88 points
Joshua - 71 points
Owen - 60 points
Wilson - 54 points
James - 53 points
Alex Ge - 51 points
Karl - 39 points
Katerina, Andy Y - 20 points
Marcus - 19 points
Nathaniel - 18 points


Rook + pawns endgame