### Killbox

The first area of attention is the killbox. Is there already a killbox, or must you erect the walls first? Is the king already in the killbox, or must you chase him into it? Have you already access to the killbox or must you pry it open with a sacrifice first?

All normal tactics can play a role. Like double attack, discovered attack, clearance, pin, blockade, lure, magnet et cetera.

Tempo moves are extremely important. 80% are checks, the rest mostly threatening mate in one. Capture is irrelevant.

What patterns and logic plays a role with a killbox?

A few examples

 Diagram 1. Black to move. Mate in 3

6k1/1p4n1/8/2RPQ3/4p3/P3qbP1/7K/2R5 b - - 1 1

[solution]

Here you must divide the killzone first. The white king must decide in which killbox he wants to be mated. The black queen  must split the killzone by a double attack, where the double attack means delivering mate in killbox 1 or in killbox 2. This splitting is a common theme.

 Diagram 2. Black to move. Mate in 3

3r2k1/2p2pb1/1p1r3p/p5p1/P3P3/1P2NnPq/QB3PN1/3RRK2 b - - 0 1

[solution]

Another common theme is to cover the escape square. At all costs, in this case.

 Diagram 3. White to move. Mate in 3

r4k2/4p3/5NpN/1bp1Q3/P7/7P/1P4PK/3q4 w - - 1 2

[solution]

Another common theme. The white king is in the killbox, but there is no adequate check to deliver mate. A common tactic as a discovered attack adds a duplo threat to the equation.

 Diagram 4. Black to move. Mate in 3

6k1/p1p2Rbp/b6q/2pBP3/2P3Q1/P5P1/1r1n3P/6K1 b - - 0 1

[solution]

There is no killbox yet. The queen sac serves only one purpose: that the next move can be done with double check. The tempo battle is extremely important, and a recurring theme in every mate.

 Diagram 5. White to move. Mate in 3

2r1k3/2q5/p1rbp1R1/2pp3Q/1P1P1P2/P3P3/7P/2R3K1 w - - 0 2

[solution]

Here you must erect the walls of the killbox first. You do that with a discovered attack. The second goal is to chase the king away from the point of pressure f8.

You see, it is not exactly rocket science. When you work your way through a themed database of 250 mates, you start to see the common logic.

1. In Diagram 1, it is obvious that Black must begin with a check by the Queen. WHY? Because the Black Knight is providing the only “shade” for the Black King and it is too far away to impact the White King. Because the Black Bishop needs to remain on f3, creating one “wall” (g2-g3-g4) of the killzone (“box”) in conjunction with the WPg3. This is a classic “corridor mate” clue. That only leaves a Queen move with check. There are only two possible Queen checks:

1...Qh6+

A “gut feeling” says that Black will NOT be able to finish the job in 3 moves. (This little caveat requiring 3 moves would NOT be applicable during an actual game, because there would be nothing to indicate that a faster mate is available.) After 2. Kg1 Qh1+ 3. Kf2 Qg2+, White still has an “escape square” at e3. We abandon this variation altogether, because of the problem requirement.

1...Qd2+

White only has two possible replies.

2. Kg1 Qg2# is easily dismissed, again because of the problem requirement. Why would White make the mate easier to achieve??

2. Kh3 SHOULD [might?] invoke the “familiar” corridor mate pattern of Bishop and Rook (or Bishop and Queen) (rotated 90 degrees from the usual pattern along the back rank). The visual “key” may be the opposition of the Bishop to the King with a Pawn in-between them, with the King on the edge of the board. I think this “rotation” might prevent System 1 from triggering on this pattern.

If that corridor mate pattern IS retrieved and brought to System 2’s attention, it is easy to “see” that 2...Qh6+ will be fatal. White can only toss his Queen into the piece shredder, with mate to follow: 3. Qh5 Qxh5#.

1. The point is to find a form of logic reasoning that becomes the guide of your thoughts instead of trial and error.

2. Since trial and error is good enough for simple cases, but it is insufficient when there are too many branches on the tree of analysis. You can't do without pruning by logical reasoning then.

3. As can be seen from my comments above, I used the method of elimination to LOGICALLY prune my area of investigation. Unfortunately, that eliminating factor was the (artificial) puzzle requirement for reaching mate in 3 moves. That factor would not exist in a game situation. Perhaps we should approach each training puzzle by first eliminating at least that artificial constraint from consideration - a very difficult (if not impossible) thing to do when it is right in front of our faces!

4. Interesting. I will omit this information in the future.