# Puzzle of the week #143

Level:
5-Queen
Chess Diagram:

I missed posting a puzzle this past week for being very busy with organizing a festival; still I found 5 minutes and did at least one puzzle a day. Did you do the same?
This present puzzle shows Black in a cramped position, but at first glance it is not at all clear what can White do to end the game quickly. There aren't enough pieces left on the board for anything spectacular such as a bone crushing sacrifice. I looked at it first searching for spectacular play, then I went away from it for a few hours and when I came back the solution appeared to me nice and clear. Your tasks:
a) White to move and win;
b) What details in Black's position is White using to end the game?

Total available points for this puzzle is 20. The answers will be published next week together with puzzle #144.

Puzzle #142 solution:
I got pretty disappointing answers for this quite simple endgame. First of all there were only 3 answers (was expecting far more) and secondly only one was good. Karl is solving them really well and I wish him the same success in his chess games. His answer:
"My instinct told me it was a King move and not a pawn move in this position, however the most logical try here (at a glance) is c6. But it won't work as this is what will happen:
1.c6 Kc8
If 1... bxc6?? then 2.b7 ... wins
2.Kc5 Kb8
If 2.cxb7? ... then 2. ... Kxb7 3.Kc5 Kb8 and Black can hold a draw using the "pawn on the sixth rank and the enemy King behind it combined with opposition" rule. The Black King always has opposition unless the White King is on c5 or a5, then he goes Kb8. Note that pawns on the h- or a-file will always result in a draw if played properly.
If 2... bxc6? then 3.Kxc6 ... with opposition wins.
3.c7 Kd7 is one of the possible lines, but it results in stalemate or draw because the Black King can just keep going back and forth on c8 and d7. White has no way of going around the pawns because Black has opposition, so it's a draw. But this is the real solution:

1.Ke6!! ...
An exceptionally good move, as it tries to lure the Black King away from the pawns. If Ke8, keeping the opposition, then White can simply push the pawns to a win. If Black moves Kc8 then white has the opposition (diagonal opposition).
1... Ke8
2.c6! bxc6
3.b7 ... wins

Or:
1... Kc8
2.Ke7! Kb8
3.Kd7 Ka8

A lot of these moves are forced so Black has no possible way of escaping. Now the Black King is in a corner and White can push the pawns to victory (again!)
4.c6 bxc6
If 4... Kb8 then 5.c7 Ka8 6.c8Q# wins.
5.Kc7! c5

Only move, trapping the escape route of the Black King.
6.b7+ Ka7
7.b8Q+ Ka6
8.Qb6#

All forced. Great puzzle!"

Correct solutions:
Karl - 20 points
Alex, Frank - 5 points
Frank - 20 points for puzzle #141

STANDINGS

Karl - 289 points
Jeffrey - 230 points
Rick - 174 points
Frank - 147 points
Alex - 111 points
Owen - 95 points
Edwin - 72 points
Nathaniel - 60 points

Comment:

Subtle details, yet effective