Kyu Exercise 75 / Solution

Sub-page of KyuExercise75

Status

[Diagram]

Problem diagram

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



Black first

[Diagram]

Black first

If Black first, several moves kill. B1 is one of them.



White first

Solution

[Diagram]

White first

If White first, the key move is the tesuji of W1.

[Diagram]

Black loses three stones

If B2 here, then the wedge at W3 is a common tesuji that captures the three Black stones.

[Diagram]

Next move

B2 is the strongest resistance. W3 is the only move.

[Diagram]

Main line 1 (B6 at white+circle)

This sequence is forced. White makes Black into a dumpling shape and lives with W7.

See BQM 374 for a discussion on whether W7 at a would be a better move.

[Diagram]

Main line 2 (B8 at white+circle)

If B4 here[1], then the result is similar to the previous diagram.



Failure

[Diagram]

Mistake

A mistake would be to play W3 here, because B4 can descend. White can at best make a two-stage ko.

[Diagram]

Mistake

The previous diagram also explains why W1 should not be played as shown in this diagram. Because after B4, the situation transposes to the previous diagram.

[Diagram]

Mistake

If W1 plays the hane first, then B2 can make a net instead of playing at B4. White is unable to make an eye in the corner.


[1]

Bill: Is B4 better than simply capturing white+circle? A difference game helps us tell. Let us set up mirror positions, and then show the resulting gote positions after Black pushes before capturing, but White, in the mirror position, simply captures.

[Diagram]

Difference game, Black first

Bill: If Black kills, White does, too, for jigo. So B1 and W2 live, and then Black wins by 1 point.

[Diagram]

Difference game, White first

Bill: But if White plays first, Black keeps jigo with B2.

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.



This is a copy of the living page "Kyu Exercise 75 / Solution" at Sensei's Library.
(OC) 2014 the Authors, published under the OpenContent License V1.0.
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