We will present Joachim Meinhardt's alternative move suggestions, which in principle all aim at a semeai between Black's large group in the upper right and White's centre group.

Unlike our historical attempts, which resulted in a variation of Joachim's Ko-Semeai, KataGo suggests that Black dispenses with Joachim's Hiki on the upper edge to minimise the amount of his defeat.

In the process, we will again experience surprising White invasions of Black's upper left corner.

If Black tries harder, however, KataGo will use Joachim's Ko-Semeai to take a higher victory for White.

Referenced by ( 2031)

Let's go back in time and enter the world of amateurs ...

: ( 2022MainLine)
Black plays hane at the top, following one of Joachim's Meinhardt's suggestions.

Black aims at weakening White's eye shape at the top.

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White is forced to answer from above.

She cannot cut at , instead.
However, that alternative move deserves attention for a very different reason; it leads to a seki across half the board with a new type of seki, called "Circular Hanezeki".

As part of his research into unusual shapes on the Go board, Harry had predicted the existence of such a seki, but without finding a use case for it.

For further details, please refer to the history of our research ...
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Black connects, of course.

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White starts a variation of the Crosscut Sequence in the upper left centre.

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This connection will prove to be the gravedigger for Black's deviation from the solution sequence.
White now looks very deeply into Black's upper left corner.

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Black plays Joachim Meinhardt's Hiki, a large endgame move.
He also has the idea of Joachim's Ko-Semeai between Black's large group in the upper right and White's centre group in mind.

Black did not occupy White's Main Semeai Liberty , and so lost one tempo in the Main Semeai by Joachim's Hiki.
This implies that Black will be unable to connect both his hasami-tsuke stones .

Let's find out what KataGo thinks about this matter ...

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KataGo favours Michael Redmond's Kikashi in the Bamboo Joint.

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White must answer with the atari.

: ( A 2030a)
With small reverse komi, e.g. with komi = -1, KataGo also favours Joachim's Hiki.

With larger reverse komi (obviously more appropriate for the analysis), KataGo favours , instead, so continuing with the course of the Main Semeai for a while.
This line will substantially reduce the amount of Black's defeat.

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White prevents her group at the left from becoming captured easily.

: ( 2030c)
KataGo favours this connection at the top, closing the right border of his upper left corner.

However, this move leaves White's Main Semeai Liberty unoccupied for a second time. It is clear now that Black will lose the Punishment Semeai, as he has fallen below the Punishment Semeai Liberty Level.

Please follow the subvariation to see what will happen after Black played at , instead.

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White occupies the Guzumi Point.

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Black continues with the Nakade Sequence at the left edge.

You might wonder why KataGo does not choose Joachim's Ko-Semeai, instead. Well, the answer is simple: Black will not get all the required points at the right.
White's Main Semeai Liberty is still unoccupied. Thus, it is not necessary for her to capture Black's nakade stones to live independently on the left side.
After , , , , the points and are still miai, which makes Joachim's Ko-Semeai impossible.

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White captures Black's hasami-tsuke stone.

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White captures Black's second stone at the upper edge.

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We have reached Black's decision point now.

Black's large group at the right has only six liberties left, which would make it the prey of the Punishment Semeai.

White's large group at the left has five liberties left (3 x , ), one more than "usual".
However, this is as many liberties as Black's hanezeki group in the lower left would have after the connection of the hanezeki's tail (5 x ).

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Therefore, Black connects the hanezeki's tail, intending to capture White's left-hand group.

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White's oki is mandatory.

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Black continues with occupying White's liberties at the left, ...

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... while White is busy with occupying Black's liberties in the lower right.

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White captures Black's three stones in the corner.

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Black occupies the last but one liberty of White's left-hand group.

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White secures two eyes for her corner group.

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Black continues with the endgame on the left side of the board.

Before the end of the game, he will have to take White's group off the board with .
As a matter of course, all remaining Black groups at the right are dead.

White wins the game by 44 points.

Compared to the "usual" Semeai Variation, where Black's marked group would be alive but White's marked group dead, the territorial swing in the lower right is about 50 points in White's favour.

The Punishment Semeai would end about 40 points worse for Black.

2022MainLine