Saturday, August 02, 2014

Checkmate in 9



White to move and checkmate in 9 moves. Can you find it without computer assistance?

8/5pk1/2R1r2p/5R2/3PQ3/1qp2PK1/r7/8 w - - 0 1

4 comments:

Harry Hariharan said...

Main Line stretching to nine moves.
At move 3, White is threatening mate in 1 move at Qh8 or mate in 2 along seventh rank. Black cannot prevent it but can only extend the game to 9 moves through 5 spite checks! Obviously if there are lesser spite checks, white will mate by move 4-5.
1. Rxf7+ Kxf7
2. Rc7+ Ke8
3. Qh7!!! Rg2+
4. Kxg2 Qa2+
5. Kg3 Qg2+
6. Kxg2 Re2+
7. Kg3 Rg2+
8. Kxg2 c2
9. Qe7#

1st move variants-2
1. Rxf7+ Kg8/h8
2. Qh7#


2nd movie variants-main 4
2A
1. Rxf7+ Kxf7
2. Rc7+ Kg8
3. Qh7+ Kf8
4. Qh8/f7#

2B
1. Rxf7+ Kxf7
2. Rc7+ Kf6
3. Qf4+ Kg6
4. Qf7+ Kg5
5. f4#

2CA
1. Rxf7+ Kxf7
2. Rc7+ Kf8
3. Qf5+ Kg8
4. Qf7+ Kh8
5. Qh7#

2CB
1. Rxf7+ Kxf7
2. Rc7+ Kf8
3. Qf5+ Ke8
4. Qf7+ Kd8
5. Qd7#

2CC
1. Rxf7+ Kxf7
2. Rc7+ Kf8
3. Qf5+ Rf6
4. Qf5+ & 5.Qe/f/g7#

2DA
1. Rxf7+ Kxf7
2. Rc7+ Re7
3. Rxe7+ Kg8
4. Qh7+ Kf8
5. Qg7#

2DB
1. Rxf7+ Kxf7
2. Rc7+ Re7
3. Rxe7+ Kf6
4. Qe5+ Kg6
5. Rg7#

2DC
1. Rxf7+ Kxf7
2. Rc7+ Re7
3. Rxe7+ Kf8
4. Re8+ Kf7
5. Qe7+ Kg6
6. Qd6+ Qe6
7. Qxe6+ Kg7
8. Rg8+ Kh7
9. Qg6#

3rd move variants
Apart from the main line the following longest line also leads to mate in 9 where black utilizes 4 spite checks.
1. Rxf7+ Kxf7
2. Rc7+ Ke8
3. Qh7 Rg2+
4. Kxg2 Qa2+
5. Kg3 Qg2+
6. Kxg2 Rg6+
7. Qxg6+ Kd8
8. Qd6+ Ke8
9. Qe7#

Obviously if there are lesser spite checks, white will mate by move 4-5.

Harry

Yancey Ward said...

I would expect this starts with Rxf7.

1. Rf7 Kf7 (Qh7# otherwise)

Now the question is which check is next? Rc7 makes the most sense to me since the rook can't really block on e7 and the king can't go to f6 (the problem I see with 2.Qh7).

2. Rc7 Ke8

Or [2. ...Re7 3.Qe7 Kg6 4.Qg7 Kf5 5.Qe5 Kg6 6.Rg7#]; or [2. ...Kf8 3.Qf5 with Qf7 and mate to follow]; or [2. ...Kf6 3.Qf4 Kg6 4.Qf7 Kg5 5.f4#]; or [2. ...Kg8 3.Qh7 Kf8 4.Qf7#]. Continuing:

3. Qh7

I looked at this a long while- black's cover on the b and a files was a hindrance to basically any other plan I could think of. However, Qh7 isn't hard to find, in my opinion- it threatens mate by two methods, and the white queen still covers g6 stopping black's only other checking move. Continuing:

3. .....Rg2 (longest line I see)

Or [3. ...Rg6 4.Qg6 Kd8 5.Qd6 Ke8 6.Qe7#]. Every other move is mate on the next move. Continuing:

4. Kg2 Qb2

By my count, Qc2 won't delay things any longer, and Qa2 or Re2 check won't be any longer after 5.Kg3. Continuing:

5. Kg3 and all black has left are the delaying sacrifices of the queen and rook. By my count, white mates in no more than 9 moves total.

Anonymous said...

No I sure can't find the checkmate in 9. But at least I think I can see enough after 1.Rxf7+ that, as a practical matter, I would find this worth playing for and taking the chance. After 1... Kxf7, I originally thought 2. Qh7 was best, but after looking rather too long and too slowly, I think perhaps 2. Rc7+ is best. At any rate, I'll summarize some of the main lines after that move

1. Rxf7+!? Kxf7
2. Rc7+ Ke8 Instead .... Kf6, 3. Qf4+ Kg6, 4. Qf7+ Kg5, 5. f4#. Also 2... Kg8, 3. Qh7+ and mate next move. The Rook interposition 2...Re7, 3. Qxe7+ looks hopeless for Black. That leaves 2...Kf8, which I think transposes into this line after 3. Qf5+ Ke8, 4. Qh7

3. Qh7 ... At first I rejected the "quiet move" - quiet in the sense that it's withut check and gives Black one move to do something. But I now think this is strong although I rather doubt it's "checkmate in 9". Mate is threatened along both the back rank and on the 7th rank. What can Black do? The Rook on the a-file can't go back and defend on either the 7th or the 8th rank. The Queen can prepare to interpose on the back rank with 3...Qb4, but that doesn't stop the mate beginning with either Qd7 or Qf7. If the other Rook checks with 3...Rg6+, 4. Qxg6 is with check and will mate, e.g 4...Kd8, 5. Qd6+ and mate next.

3. ... Rg2+
4. Kxg2 Qc2+
5. Qxc2 .... Okay, maybe White won't mate in 9 but White is easily winning so I'm satisfied! Unless I'm completely missing a resource for Black which is always possible.
- Craigaroo

davey said...

1. Rxf7+ Kxf7
2. Qh7+ does mate, but in 11 moves!