Kyu Exercise 75 / Solution

Problem diagram  

The status is: Black first kills, White first lives.

Black first

Black first  

If Black first, several moves kill. is one of them.

White first

Solution

White first  

If White first, the key move is the tesuji of .

Black loses three stones  

If here, then the wedge at is a common tesuji that captures the three Black stones.

Next move  

is the strongest resistance. is the only move.

Main line 1 ( at )  

This sequence is forced. White makes Black into a dumpling shape and lives with .

See BQM 374 for a discussion on whether at a would be a better move.

Main line 2 ( at )  

If here^[1], then the result is similar to the previous diagram.

Failure

Mistake  

A mistake would be to play here, because can descend. White can at best make a two-stage ko.

Mistake  

The previous diagram also explains why should not be played as shown in this diagram. Because after , the situation transposes to the previous diagram.

Mistake  

If plays the hane first, then can make a net instead of playing at . White is unable to make an eye in the corner.

Difference game, Black first  

Bill: If Black kills, White does, too, for jigo. So and live, and then Black wins by 1 point.

Difference game, White first  

Bill: But if White plays first, Black keeps jigo with .

The difference game favors Black, so Black should push before capturing, unless the ko situation dictates otherwise. Main line 2 is normally superior for Black to main line 1.