Dochi Yose Tesuji

  Difficulty: Advanced   Keywords: EndGame, Tesuji

In a game played on November 24, 1705 between Honinbo Dochi (Black) and Yasui Senkaku (White), Dochi seemed to be losing by a few points in the endgame, when he suddenly played a brilliant endgame tesuji.


[Diagram]
Moves 225-232  

B1 began the brilliant sequence of moves that saved the game for Dochi.

[Diagram]
Continuation (Moves 233-236)  

The invasion made B1 and B3 sente, because if White does not capture the marked stone with W4, Black would play at a and make a seki.

The invasion does not work if it is played after the hane-connect sequence.


You may wonder whether White has no other way to play:

[Diagram]
White's alternative  

The other reasonable move for White is to play 4 here instead of a. Black next plays 5 and 7. If this is not sente, White has refuted Black's play.

[Diagram]
Var 1: Black fails  

B1 is an eye-stealing tesuji, as it makes the eye at a false, but W2 is a good response and Black's attack runs into nothing. No matter how hard he tries, e.g. with B3 and so on, Black cannot get a seki, ko, or anything else.


[Diagram]
Var 2: Black succeeds  

The solution for Black is to play on White's vital point himself, with B1.

W2 is forced, as a move here would be rather awkward for White. Next, B3 is tesuji and B7 establishes an eye in the corner. Thus the position becomes a seki.


As can be seen, if White did not reply, he would lose his corner territory (in a seki with Black). Therefore, White had to add another move to defend his territory after Black played hane-connect at the top border. The hane became Black's sente and enables him to win the game.


[Diagram]
Variation at 233  

If Black continues playing inside, e.g. with 233 at B1 here, there is no real difference to the game. At worst, Black has lost a ko threat.

Anonymous : W4 is self-atari. Thus W2 is called into question.

Anonymous2: The author should indeed reconsider W4


Dochi Yose Tesuji last edited by 2.13.248.100 on July 24, 2016 - 17:16
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