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Teaching Game 67, Tsumego after W52
PageType: OngoingGame   Difficulty: Beginner   Keywords: Life & Death

This was the situation in the TeachingGame67 after W52 (the marked stone):

[Diagram]
Diag.: TG67 Tsumego


The white group on the RS is an example of a three-spaces notcher.
Taken in isolation and being six spaces long, his status is unsettled: unfortunately it is black's turn and so the group could be killed by a play at the vital point a. The strongest resistance is W b, but to no avail: there are a number of sequences but all fail. Try to work them out.

But real-life Tsumego is complicated by the surrounding positions: fortunately this time, W has an ally in the LR group: a white move at c threatens to link up there with the sequence Wd, Be, Wf. Therefore W can work out a Ko this way:

[Diagram]
Diag.: Ko


Needless to say, this is a HanamiKo for black, i.e. he risks very little (also because he gets to capture first), while white risks a lot.

Actually this is not the best sequence to get the ko: if W plays 4 at 6 she gets to capture first, which is obviuosly an improvement (see the actual development in the game of the Path not taken).

The sequence Joe believed could lead to a Seki is probably this one:

JoeSeki Indeed it was what I thought was a seki. I saw the aji of "c" and thought that gave me enough time to either escape to the bottom or make a big enough room to get a seki.

[Diagram]
Diag.: Seki? Mmmmhh... not really!


This may look like a seki, but it is not: black has made an EyeInTheBelly? of white's group: she cannot capture those stones else she ends up with a space AlmostFilled with a dead shape, while black can always occupy all the external liberties, then play a and b to put the group in atari.
The move B51 (the marked stone) was played not only to seal white in without any remaining Aji (Altough I wonder whether it would have been better if it was played a space below, at c...), but also to stop W6 from being Sente: else a seki would have indeed been possible by threatening to escape:

[Diagram]
Diag.: Without B51 B is forced to defend at 7


The problem of making life for this group could have been probably solved earlier by playing differently after I connected with the marked stone in the dia. below, by expanding the space starting at the other side:

[Diagram]
Diag.: Alive, but...?


This should be alive, but this sequence has the drawback of B2, that weakens the LR white corner.
It is also true that black is full of holes in the upper RS...



This is a copy of the living page "Teaching Game 67, Tsumego after W52" at Sensei's Library.
(C) the Authors, published under the OpenContent License V1.0.