Puzzle of the week #112

Level: 
4-Rook
Chess Diagram: 

--------
--p-----
--------
--------
-----P-k
p-------
-------P
--K-----

In the past little while we had to deal with 6 complicated middle game puzzles, so it is time to switch our attention to another basic endgame for a change. We already know the importance of passed pawns in King and pawns endgames and here we have no less than 4 such pawns on the board. There is a very nice method of play you need to remember in order to find the solution, method we have done at the club. Actually the admission test to level 5 has a puzzle where this method is being used. Without further ado here are your simple tasks for the week:
a) White to move and win;
b) explain your solution.

Total available points for this puzzle is 20. The answers will be published next week together with puzzle #113.

Puzzle #111 solution:
This was not an easy puzzle. It has remained in history as a very good practice material after the game Smyslov - Hort, Interzonal, Petropolis, Brazil 1973. I really appreciated your work in analysing the position and most of you have written down quite a few good things. Of course writing your ideas could be improved, but in general you guys should be proud of your work. It is for the second week in a row when Owen has the most complete response; congratulations! Please read Canadian GM Kevin Spraggett's analysis below and compare it with your answer:
"Now Hort must exchange Knights with 26... Nxg4 27. Qxg4 Re7. Instead, he walks into a ferocious attack:
26... Re7? 27.Bxe5! dxe5 28.Nf6! ...
Clearly Black can not play 28... gxf6 29.gxf6+ Kh8 30.fxe7 ... and White wins as he pleases
29.Nxh7! ...
Ouch! That damn Knight is so annoying... Black is busted. If 29... Kxh7 then White breaks thru with 30.g6+! fxg6 31.Rxf8 ... with mating threats; Or if  29... Rd7 30.Nxf8 Rxf8 31.Qh4 Kg8 32.g6 ... with a mating attack.
29... Re6
Best is to resign, but nobody likes to resign in less than 30 moves...
30.Rxf7 ...
Hort continues for the spectators
30... Bc5+ 31.Kh1 Re7 32.Rf8 ... 1-0
It is forced mate.  Hort has had enough! Give that King Knight a cigar(!) for a job well done..."

Correct solutions:
Owen - 25 points
Andy Y, Edwin, Karl - 20 points
Jeffrey, Andy Q, Nathaniel, Humphrey - 15 points
James - 10 points

STANDINGS

Owen - 234 points
Karl - 220 points
Andy Y - 218 points
Andy Q - 214 points
Humphrey - 175 points
Edwin - 172 points
Alex - 158 points
Jeffrey - 133 points
James - 128 points
Amir - 103 points
Nathaniel - 100 points
Rick, Marko - 10 points

Comment: 

What is the method?