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 for the main line that Black sacrifices his hasami-tsuke stones completely to minimise the amount of his defeat.

If Black tries harder, however, KataGo will come up with an invasion of the upper left corner as a surprising countermeasure.

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

: ( 2022MainLine)
Black's wedge in the right centre is a suggestion of Joachim Meinhardt; aiming at reducing the number fo shared liberties in this area, which - in the case of a semeai between Black's large group at the right and White's centre group - would favour White.

For further details, please refer to the history of our research ...
127

Please note that we had already played Fujisawa Hideyuki's First and my Second Throw-in at that time, but still refrained from inserting the kikashi in the hanezeki "early".

:
White is forced to give atari from the right.

:
Black connects.

:
White is forced to connect her centre stones below.

Black loses a Main Semeai Liberty by this move.
This implies that he will be unable to connect both hasami-tsuke stones .

:
The wandering of the hanezeki's tail continues as usual.

: (A 2029)
Black pushes to the left.

He might want to play the hane at the top, instead, following another one of Joachim's suggestions, which aims at weakening White's eye shape at the top.
We will discuss this move at the end of this section.

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Black starts the Crosscut Sequence in the left centre.

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Black tries Joachim's Hiki here, aiming at attacking White's group at the top.

He already knows that he will be unable to win the game by following the Main Semeai with occupying White's liberty at , instead.

For further details, please refer to the history of our research ...
128

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

: (A 2029)
KataGo likes to insert Michael Redmond's Kikashi in the Bamboo Joint first.

As is already mentioned above, Joachim continued with his Hiki to , instead.

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White answers with the atari, taking profit at the upper edge.

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Black closes the hole in the lower border of his upper left corner, so choosing the Main Semeai.

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Black initiates the Guzumi Exchange.

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As usual, KataGo likes to play the kikashi in the hanezeki early.

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The Nakade Sequence continues.

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Black ends in gote.

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White must play Yamada Shinji's Tsuke in due time.

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Black is still par with the Punishment Semeai Liberty Level, so White takes the opportunity to capture Black's hasami-tsuke stone.

Please note that his capture is for free, as it erases the earlier approach-move liberty at .
White will also be able to capture the second hasami-tsuke stone with later.

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Black gives atari at White's two stones in the lower left.

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White continues the interrupted sequence in the upper left corner.

She is unable to connect her two stones in atari with in the lower left, as this move would cost her two tempi in the Main Semeai, and it would also cause Black to play the large endgame move at himself.

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Black answers with the atari at the upper edge.

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White's hasami-tsuke starts the reduction of Black's lower left corner.

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White captures the second hasami-tsuke stone at the upper edge.

She must do so now, because continuing with at the lower edge is not absolute sente locally.

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Black defends in the left centre, also continuing with the Main Semeai.

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Now, White gives atari at Black's single stone in the lower left corner.

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KataGo chooses Jérôme Hubert's Solid Connection here.

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White gives atari in the upper left.

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Black captures, of course.

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White connects her just played stone in atari.

Please note that she ended the endgame sequence on the left side of the board in gote, so losing one tempo in the Main Semeai.

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Black caputures White's two stones in the lower left.

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White defends her territory at the upper edge.

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Black is able to capture White's single stone at the upper edge.

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White inserts her kikashi in the left centre, ...

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... before answering at the upper edge.

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Black connects his stone in atari.

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The Main Semeai continues.

Capture Variation:

Compared to the super²ordinate variation, ...

• White destroyed two points of Black's territory in the upper left corner.
• White got an additional two points of territory at the top.
• White's cumulated gain in the upper right corner is seven points.
• Black got an additional point of territory in the left centre.
• Black captured White's two stones in the lower left, so gaining four points.
• White did not capture Black's single stone in the lower left, so losing two points.
• White captured an additional Black stone in the hanezeki's tail, so gaining two points.

In total, Black lost six points.

White + 2 => White + 8

After a short detour into the world of amateurs ...

( 2029)
VAR

: ( 2029)
We inserted Joachim's Hiki manually.

Please note that Black did not occupy White's liberty , so losing another tempo in the Main Semeai.
He has just fallen below par with the Punishment Semeai Liberty Level.

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White makes sure that her stones on the left side cannot be captured easily.

Black, however, is unable to continue with the Main Semeai (i.e. with occupying White's liberty ), due to his loss of an own Main Semei Liberty through White's connection at much earlier.

: (A 2029a)
Black captures White's single stone in the right centre, aiming at a semeai with White's centre group.

After the cannon thunder has died down further below, White will capture Black's nakade stones.
You may wonder to what extent it would make a difference if Black saved these stones in the first place (in sente, as White must secure independent life for her left-hand group thereafter), starting with a move at . You will find an answer in the subvariation.

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White has to occupy the Guzumi Point.

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KataGo pushes from the left first, reducing White's potential eye space at the top, ...

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... before reducing White's liberties in the centre through creating a false eye with this throw-in.

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Black creates a second false eye in White's formation.

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White pushes into the hole of Black's encirclement in the upper left corner.

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Black has to connect his stone in atari.

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Thereafter, KataGo starts one of its surprising attacks on Black's upper left corner from the inside.

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Black defends with a diagonal move of his own at the right.

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White's descent keeps Black's forces separated.

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Black tries to reduce White's liberties, while keeping the ownership of the corner.

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White starts with the creation of cutting points in Black's formation at the left edge.

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Black must seal White's group in.

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White's throw-in is decisive for spoiling Black's shape.

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White reduces the size of Black's eye in the corner.

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White's atari initiates a ko-fight at the left edge.

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White captures the hanezeki's tail as a ko-threat.

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Black recaptures, as a matter of course.

Ko: ; ; ; ;

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White has plenty of ko-threats in the nakade, starting with Joachim's Rediscovered Oki.

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Black is restricted to ko-threats in the upper left and in the Nakade Area.

Black's large group in the upper right is already alive, so the forcing moves and in the hanezeki are worthless here.

Ko:

...

Ko:

...

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White captures the ko for the last time.

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Black does not have any valid ko-threat left, so he prepares for the life of part of his stones in the upper left.

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Black secures a second eye for his remaining group at the top, which is larger than saving his nakade stones.

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White captures Black's nakade stones in return.

• Black will continue with , close the left-hand borders of his lower left corner, and thereafter the right-hand one with .
• He will reduce White's upper left corner a bit, starting with and .
• He will also be able to connect his hasami-tsuke stone with .
• White lost some points in the nakade.

But Black does not have any compensation for the loss of the larger part of his upper left corner.

Please note that the capture of Black's nakade stones does not play a major role here, as these would have been lost in the Main Semeai anyway.

White will win the game by 15 points.

2029

Many years before in the world of amateurs ...

VAR

: ( 2029)
Black plays a hane at the top, following one of Joachim's suggestions.

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White must answer from above.

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Black connects his just played stone.

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White continues with some variation of the Crosscut Sequence n the left centre.

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Joachim's Hiki at the upper edge aims at a semeai between Black's large group at the right and White's group at the top / in the centre.

Please note that he did not occupy White's Main Semeai Liberty at .

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

:
We inserted Joachim's Hiki manually.

Please note that Black did not occupy White's liberty , so losing another tempo in the Main Semeai.
He has just fallen below par with the Punishment Semeai Liberty Level.

:
KataGo pushes once into Black's upper left corner, as we also did.

However, KataGo utilises this move as a preparation for an attack on Black's upper left corner, while we aimed at increasing the liberty count of White's group at the top.

:
Thereafter, White makes sure that her stones on the left side cannot be captured easily.

Black is unable to continue with the Main Semeai on the left side with , instead, due to his loss of an own Main Semei Liberty through White's connection at much earlier.

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Black attacks White's eye shape at the top.

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KataGo starts another one of its surprising attacks on Black's upper left corner from the inside.

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KataGo likes to insert this kikashi at the left edge, ...

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... before answering in the upper left corner.

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White blocks the corner, intending to gain its ownership.

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Black seals White's forces in, also connecting his own.

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White's descent enlarges her eye space in the corner.

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White's atari at the left edge ...

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... forces Black to connect.

As usual, he is unable to fight a ko with , instead.

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White captures the hanezeki's tail, getting rid of any potential shortage of liberties for her cut-off upper group on the left side.

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Black recaptures.

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White continues with the semeai in the upper left corner.

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Black's oki is mandatory.

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White solidifies her shape in the corner.

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Black's hane aims at creating difficulties to approach his group from the upper edge, and also threatens to make miai between living independently of connecting to his allies to the right.

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White plays an oki of her own, also erasing the aforementioned threat.

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Black occupies a shared liberty.

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Black occupies another outside liberty of White's corner group.

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White must prevent Black from occupying this point.

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White seals Black's group securely in.

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Black continues with occupying White's liberties.

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But it will turn out that White's eye is too big to die.

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Black captures White's two stones in the lower left corner.

Black's group in the upper left corner has only three liberties left (3 x ), while White's group has five (, 2 x ).
Thus; continuing with this semeai would become a lost move for Black, as White is clearly ahead in liberties.

:
Joachim's Rediscovered Oki continues the dissolving of the hanezeki.
Thereafter, White will descend to at the left edge, capturing Black's nakade stones above.

Black cannot find any compensation for the loss of his upper left corner.

White will win the game by a large margin.

2029

2022MainLine