## Saturday, December 26, 2009

### The twelve puzzles of Christmas

White to play and win

Jonathan B said...

I'm going to struggle with this one since my k and p knowledge is somewhat lacking.

Only 5 moves to consider - but they all look much of a muchness to me at the moment.

For now I'm investigating the Agatha ... but I@m not sure I see it makes much difference.

Let's have another look ...

Jonathan B said...

OK, I think I might have it.

Going straight for the pawn doesn't work since something like

1. Ke7 Kg6
2. Kd6 Kf6
etc

the Black king comes to d5 and snaffles the white pawn.

So White needs to get a tempo somewhere.

I had a look at 1. b3 (on the grounds that it's the least likely looking move) but Black has

1. ... Kg6 in response.

So, by process of elimination,

1. Kf7 Kh6
2. Kf6 Kh7

and White has his extra tempo.

I thought it didn't make a difference at first because the White queen is two tempi away from d6 on f6 just as it is on f8 so

3. Ke6 Kg6
4. Kd6 Kf6

is just the same as the first line I looked at. Then I finally realised that White can play

3. b4 Kh6
4. Ke6 Kg6
5. Kd6 Kf6
6. Kc6 Ke6
7. Kb6 Kd5
8. Kxa6

and White wins.

If Black doesn't go back to h7 but heads to h5 then White has to play

3. Kf5 now Kh6
4. b4

and if

3. ... Kh4

White blocks the King with

4. Kf4 and keeps going until Black goes all the way to h1 if necessary. White moves the pawn to b4 whenever Black moves his king back up the board.

ejh said...

Very, very close but one detail is not quite right.

Jonathan B said...

I'll get back on it then

I haven't got a clue for tomorrow's white to play and draw. Am avoiding the comments box in case i read the solution.

an ordinary chessplayer said...

After 5 Kf3 Kh2 6 Kf2 Kh3 7 b4? black can leave white with an a-pawn: 7...Kg4 8 Ke3 Kf5 9 Kd4 Ke6 10 Kc5 a5! 11 bxa5 (11 b5 Kd7) Kd7 12 Kb6 Kc8 =.

7 b3 is correct: 7...Kg4 (7...a5 8 Ke3 Kg4 9 Kd4 Kf5 10 Kc5 a5 11 bxa5 Ke6 12 Kc6 - No draw this time.) 8 Ke3 Kf5 9 Kf4 Ke6 10 Kc5 Ke5 11 b4+-.

If black tries 6...Kh1 then 7 b4 is okay, since the black king is not en route to c8.

Is that the detail referred to?

ejh said...

Yes!

The puzzle is from Nunn, Solving in Style, Gambit, 2002.