Puzzle of the week #203

Submitted by eugen on

Long mates (4)

Level
5-Queen
Chess Diagram
[Event "Puzzle #203"][Date "2012.06.27"][Result "1-0"][SetUp "1"][FEN "rnb1kbnr/p2ppppp/1pp5/4NN2/2Q5/2K1B3/8/8 w kq - 0 1"]
This is your vacation puzzle. It requires not only precise calculations, but also some research work as well. Listen to the story behind it, written by its original inventor more than a thousand years ago:
Armies at war. A tale of a White army devastated by disease and obliged to pact peace. The Black Shah (King) orders his Firzan (Queen) to bring the White Shah (King) to his presence, but the lazy Firzan (Queen) sends 2 Baidaqs (pawns) to carry out the order; angry the Black Shah (King) executes his Firzan (Queen) and the White Shah (King) afraid at seeing the cruelty of the Black decides to launch a final attack.
White to move and win; explain your solution. The answers will be published in September 2012 together with puzzle #204.

Puzzle #202 solution:
Study by Otten. Karl's answer was the coolest:
Black: King + Bishop
While: King + 2 pawns
Position - the white pawns are on almost opposite sides of the board, so the Black King can only stop one of them, and the Black Bishop the other. But, if Black were to be given another move, it would be a draw because the Black King can move into the a-pawn's square. So, a forced first move:

[Event "Puzzle #202"][Date "2012.06.18"][Result "1-0"][SetUp "1"][FEN "8/6b1/5k2/8/P3K1P1/8/8/8 w - - 0 1"]1.a5 {The Black King can't reach the a-pawn's square anymore, and therefore only the Bishop can catch it. Currently, the Black Bishop is limited to f8, g7 and h6 (h8 is useless; why would it go there?). To protect a7, the Bishop has to be on the a7-g1 diagonal and currently the White King is guarding d4 and e3. So it's only option is to go to c5} 1...Bf8 2.Kd5! {To protect c5. "Why not Kd4?" you ask, "It protects c5 and e3, so the Bishop has no chance of stopping the pawn right?" A good try, however Black has a nice tactic in store} (2.Kd4? Bd6 3.a6 Bh2! 4.a7 Bg1+ 5.Ke4 Bxa7 {Draw}) 2...Bh6 3.g5+!! {Magnificent! Black is forced to take with the Bishop, else the King blocks it} 3...Bxg5 4.Ke4 Bh4 5.Kf3 {White wins}

Correct solutions:
Leo, Ziyao, Philip, Karl - 20 points
Daniel, Jeffrey - 19 points
Alex - 15 points
Leroy, Coco - 12 points
Justin, James, Kevin - 6 points
Derrick - 4 points

Jeffrey - 20 points for puzzle #201

FINAL STANDINGS:
Philip - 468 points
Ziyao - 409 points
Jeffrey - 350 points

James - 335 points
Daniel - 331 points
Leo - 313 points
Derrick - 272 points
Alex - 258 points
Leroy - 233 points
Coco - 225 points
Harmony - 187 points
Justin - 148 points
Kevin - 49 points
Karl - 20 points