Endgame Problem 6 / Solution

Sub-page of EndgameProblem6
White first  

White protects with W1. Later, B4 is a 1 point sente. The result is a local count of -3. (By convention, White scores are negative.)

Black first  

Black throws in with B1. Through W4 is Black's sente, reaching a three stage ko. If White wins the ko the result is -3; if Black wins, the result is +4 (next diagram).

Black wins ko  

Black has captured 2 more stones than he has lost.

It takes Black 4 net moves to win the ko and get 4 points. In 1 net move White can prevent or win the ko for -3 points. The miai value of a play is (4 - (-3))/(4 + 1) = 7/5 = 1.4 points.

The original count is -3 + 1.4 = -1.6 points.

Losing sente  

B1 is a losing sente. After W2 the local temperature has reduced to 1 1/6, a well-known yose (See Miai Values List / 1.00 to 1.99). Since W4 results in a score of -3, the local count after W2 is -3 + 1 1/6 = -1 5/6. Black has lost almost 1/4 point.

Black's original sacrifice is an endgame tesuji with a somewhat unusual point. Black gives up a stone to prevent White from playing her best play in response to B3 (B1 in the Losing sente diagram). Capturing the sacrifice stone is not as good as the solid connection.

--Bill Spight

Endgame Problem 6 / Solution last edited by Unkx80 on November 30, 2004 - 10:13
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