Endgame Tesuji 3

  Difficulty: Intermediate   Keywords: EndGame, Tesuji
[Diagram]
Position  

Consider the upper left corner in this diagram: are you surprised by W1?

[Diagram]
Sacrificing stones to aim for...  

The real endgame tesuji for White is to play the hane at W1 and another hane at W3.

[Diagram]
... the white sente descent.  

If B4 blocks, then W5 is an atari, which is sente for White.


Comparison

[Diagram]
Black plays first  

The hane-connect is often a sente endgame play for Black, which gains him 2 more points than in the previous sequence.

It is conceivable that White can omit W4, in which case Black will of course gain more; in this case the sequence is also not really sente.



The question is: how should White play in this corner if there are also large endgame plays elsewhere?

[Diagram]
Gote  

White is reluctant to play the hane-connect at W1 and W3, although it gains her 1 point more than the original sequence, because it is gote.

[Diagram]
Better  

The descent at W1 is an improvement, because it threatens to enter the corner, but this may not be good enough.

If Black does not defend, White plays as in the next diagram to reduce the corner by some 8 points at p and white+square.

If Black does defend at B2, the score is as in the original sequence. He may, however, prefer to defend elsewhere to reduce White’s ko threats.

[Diagram]
Gote again (2,6: tenuki; 9: later)  

The reason W1 may not be good enough is that if there are more urgent plays elsewhere, B2 can tenuki. While W3 and W5 can enter Black’s corner, gaining some 8 points (see above), B6 can tenuki a second time.

Black thus gets sente twice and has two plays with which to match White’s 8 points.

White is in no hurry to play W9 as Black has a shortage of liberties. This stone is mainly present for comparison with the next diagram, emphasising that W1 has become redundant.

[Diagram]
Severe  

On the other hand, if B4 after the tesuji is tenuki, then connection with atari at W5 is much more severe than W5 at a. This W5 threatens to capture three Black stones for another 8 points.

W5 may also have life and death implications depending on the configuration on the right side, since it also destroys Black’s eye in the corner. This is, however also the case when White enters Black’s corner with W3 in the previous diagram. The difference is that there the three stones are not threatened until W9, which is a dame, while here W5 threatens them and takes the corner profit; in the original sequence, W5 threatens both the corner and the stones, keeping sente.

Bill: Normally, this will not be a double sente, as that depends upon the rest of the board. So normally this is a Black sente or a White sente. If the tesuji above is sente, so will the descent be.


Author:


Endgame Tesuji 3 last edited by 107.210.159.110 on June 12, 2018 - 00:29
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