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.

Moves 225-232  

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

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:

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.

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.

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.

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 on July 24, 2016 - 17:16
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