The Hasami-Tsuke found by Harry Fearnley is in principle a "very normal" endgame tesuji, but which must have much of a kikashi inherent in it, because KataGo wants to play this move extremely early in the solution sequence.

When compared with the classical line of play, it will turn out that Harry's Hasami-Tsuke could also have been played in the original solution of Fuisawa Hideyuki 9p without disadvantages.

We will also shed light on the specific peculiarities of this move, which offer starting points for making additional use of them.

Coincidentally, the KataGo-supported analysis of a minor aspect in the following section "Fujisawa Hideyuki's First Throw-in" revealed that choosing Harry's Hasami-Tsuke Sequence for the reduction of White's upper left corner in due time would not only increase Black's flexibility in the game, but also affect the overall result, as Black would benefit by one point in the "classical" line of play (i.e. without my Guzumi, Yamada Shinji's Tsuke, as well as without most of KataGo's new moves at the left side of the board).

At the end of this section, KataGo will confirm this finding, with a ban on my Guzumi as the only restriction.

Referenced by ( 2022MainLine), ( 2025)

Let's enter the world of KataGo ...

: ( 2022MainLine)
KataGo considers the reduction of White's upper right corner, which starts with Black's push at , "extremely early".

Please note this push is only feasible due to the existence of Black's seemingly misplaced stone in the corner (see below).

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White blocks immediately with , preventing her stones to the left from becoming captured by Black.

We also analysed a White response at early in our investigations, but refrained from considering this retreating move as an alternative, because we came to the conclusion at the time that it was a few points worse for White.

However, KataGo rates this alternative move as equivalent, both in the classical solution and with my Guzumi.

For further details, please refer to the respective subvariation of the Story Line 2022 ( 2022a)

Quite the contraty, if Black's seemingly misplaced stone was not on the board, White would be able to block with at the left, also taking Black's large group a Main Semeai Liberty.
White would benefit by one point overall (not counting the then missing prisoner).

For further details, please refer to section "Black's Missing 71st Stone - Vanished" ( 2023)

Let's go back to the dawn of time ...

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This push has also been used by Fujisawa Hideyuki 9p, but much later in the game.

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White answers with the immediate block at .

As already mentioned earlier, a White move at would be also possible, not affecting the final result of the game.

For further details, please refer to the respective subvariation of the Story Line 2022 ( 2022a)

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Fujisawa Hideyuki further reduced White's upper right corner with a second push from the left, in sente.

However, as we know now, this move is a mistake.

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Thereafter, he descends to the upper edge.

Please note that Black's final move of Fujisawa Hideyuki's reduction sequence is gote locally.

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White starts the mutual occupation of opponent's liberties in the Main Semeai.

Let's return to the era of KataGo ...

: ( 2022MainLine)
It would be advisable for Black to continue with the hasami-tsuke of , a typical endgame move.

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

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This hasami-tsuke has been found by Harry Fearnley in 2009.

As we will see below, this move gains a lot of profit in conjunction with the already played Guzumi Exchange (, ).

Let's reenter the world of KataGo ...

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White draws back, in order to save her single stone that has just been attacked by Black.

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Black connects along the upper edge.

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White blocks a further Black intrusion into her corner.

:
After Harry's Hasami-Tsuke Sequence has been terminated, Black will return to the interrupted creation process of the hanezeki in the lower right, following the classical sequence of Fujisawa Hideyuki here.

Let's go back to the dawn of time again ...

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to are the classical moves chosen by Fujisawa Hidejuki.

Please note that Black's descent to is gote locally, so - in reality - this move could not be played so very early in the game.

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This block was originally played at (at a later moment in the game, of course; there is already a White stone at ), occupying another liberty of Black's group.
We have shifted this move upwards to simplify the following presentation.

Let' s enter the analysis room and stay there for a while ...

Without any reduction of White's corner, Black's large group has seven liberties () in the upper right.

After Harry's Hasami-Tsuke Sequence , , Black's large group has only six liberties left, one less than above.

However, we have to take into account that White's formation has got a decisive weakness identified by Michael Redmond 9p in 2017, in the context of the classical solution sequence, where White occupied the point of .

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Black's kikashi in the bamboo joint makes use of White's false eye at / , threatening to capture White's two stones to the left.
Please note that Black's large group got an additional liberty at by Michael Redmond's Kikashi.

White's options for answering Black's move are the solid connection of and the atari of .
will lose some points of territory, but no Main Semeai Liberty, while will avoid this territorial loss at the cost of losing one Main Semeai Liberty.

In reality, White might play in the bamboo joint first, with , . But even then adding a stone at or would be mandatory for White, in order to get rid of her shortage of liberties.
However, Black would have taken one of White's Main Semeai Liberties at the left before, so that the resulting effect on the relationship of Main Semeai Liberties is identical.

Please note that if Black played my Guzumi with , Michael Redmond's Kikashi would not have any effect.
Thus, its successful application is restricted to the classical line of play, in which White, however, has a means of compensating for its impact.

For further details, please refer to section "Michael Redmond's Kikashi in the Bamboo Joint" ( 2032).

: (A 2024)
We will study the solid connection first.

Afterwards we will focus on the atari at .

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In the later course of the game, Black will want to connect his hasami-tsuke stone.

Therafter, his group is left with seven liberties in the upper right area.

Capture Variation:

Fujisawa Hideyuki (at left):

• White got seven points of territory in the marked area.

Harry's Hasami-Tsuke (at right):

• White got three points of territory.

White lost four points of territory.

Semeai Variation:

Fujisawa Hideyuki (at left):

• White got seven points of territory in the marked area.
• White captured one Black stone, so gaining two points.

Harry's Hasami-Tsuke (at right):

• White got three points of territory.
• White captured three Black stones, so gaining six points.

No difference.

( 2024)
VAR

: ( 2024)
If White answers with the atari, the conditions in the upper right area change.

: (15 2024)
Again, Black will want to connect his hasami-tsuke stone.

However, dependent on the surrounding conditions, he might be forced to connect at , instead, so sacrificing his pivotal stone.

However, his large group is left with only six direct liberties thereafter, which is one less than above with White's solid connection.

The fate of Black's group depends on whether becomes an (additional) approach-move liberty or whether White loses at least one Main Semeai Liberty elsewhere on the board.

Under the assumption that Black survives the Punishment Semeai ...

Capture Variation:

Fujisawa Hideyuki (at left):

• White got seven points of territory in the marked area.

Harry's Hasami-Tsuke (at right):

• White got three points of territory.

White lost four points of territory.

Semeai Variation (assuming that there in no approach-move liberty in the upper right):

Fujisawa Hideyuki (at left):

• White got seven points of territory in the marked area.
• White captured one Black stone, so gaining two points.

Harry's Hasami-Tsuke (at right):

• White got four points of territory.
• White captured three Black stones, so gaining six points.

White gained one point of territory.

2024

VAR

: ( 2024)
If Black cannot afford losing a Main Semeai Liberty, he is forced to sacrifice his initially played hasami-tsuke stone.

As you will see below, the effects of this sacrifice on the liberties of Black's large group as well as White's territory in the upper right corner are identical to those of Fujisawa Hideyuki's classical reduction sequence.

This implies that Harry's Hasami-Tsuke could be played without any risk at any appropriate moment.
However, as always, the devil is in the detail in this respect, too.

Black's large group is left with seven liberties in the upper right again.

Capture Variation:

Fujisawa Hideyuki (at left):

• White got seven points of territory in the marked area.

Harry's Hasami-Tsuke (at right):

• White got five points of territory.
• White captured one Black stone, so gaining two points.

In total, White got seven points.

No difference.

Semeai Variation:

Fujisawa Hideyuki (at left):

• White got seven points of territory in the marked area.
• White captured one Black stone, so gaining two points.

In total, White got nine points.

Harry's Hasami-Tsuke (at right):

• White got five points of territory.
• White captured two Black stones, so gaining four points.

In total, White got nine points.

No difference.

2024

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

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We analysed the two different ways for reducing White's upper right corner territory in a scenario, which followed KataGo's solution to the problem, in principle, but refrained from playing my Guzumi.

My Guzumi would create additional approach-move liberties for Black's large group in the upper right, which would develop their full effect exclusively in cooperation with Harry's Hasami-Tsuke.

Please remember that KataGo played my Second Throw-in, inserted the kikashi in the temporary seki early, and captured Black's single stone in the lower left after KataGo's Atari during the creation of the nakade.

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As a matter of course, the reduction of White's upper right corner starts with the usual push from below.

: ( 104 2024)
As in the next section, we start the consideration with Fujisawa Hideyuki's subsequent second push from the left.

We enforced this move manually.

As a matter of course, KataGo would like to play Harry's Hasami-Tsuke , instead, which will turn out to carry a quite unexpected one-point benefit.

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Black ends in gote in the upper right corner, which might be the reason for the disadvantage of the previous push.

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White starts the endgame at the left side of the board with Yamada Shinji's Tsuke, ...

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... followed by KataGo's Immediate Crosscut.

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In between, White erases one of her potential weaknesses in the upper right corner.

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Black is par with the Punishment Semeai Liberty Level, and so is forced to follow White with the Main Semeai.

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

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For the second time, White erases a potential weakness in the upper right corner in between.

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Black takes the opportunity to give atari at White's two stones in the lower left.

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Black connects here, ...

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... letting White continue in the upper left corner.

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Black got sente, and so captures White's two stones in the lower left.

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The Main Semeai continues.

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Cheng's Bump in the left centre.

Black must not play any reduction.

After her decision point, White will give atari at the upper edge. Black will connect at (he will be unable to win this endgame ko), and White will take the last valuable point in the right centre with .

Capture Variation:

Compared to Our Solution (2021), ...

• 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 got an additional seven points of territory in the upper right corner.
• 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 stone in the lower left, so losing two points.
• White got an additional point of territory in the right centre.

In total, White gained five points.

White + 2 => White + 7

Semeai Variation:

Compared to Our Solution (2021), ...

• 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 got an additional six points of territory in the upper right corner.
• White captured three Black stones less in the upper right, so losing six points.
• Black got an additional point of territory in the left centre.
• Black captures two White stones less at the left, so losing four points.
• White did not capture Black's stone in the lower left, so losing two points.
• White captured one Black stone less in the right centre, so losing one point.

In total, White gained four points.

Black + 4 => Jigo

VAR

: ( 2024)
Black plays Harry's Hasami-Tsuke.

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White exchanges for , as usual.

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After that, however, White immediately connects with .

Continuing with the "usual" attachment at would be mistaken here.
Black would utilise Michael Redmond's Kikashi in the Bamboo Joint, so gaining decisively overall.

Please note that the reduction of White's upper right corner territory ends in sente for Black, which - according to KataGo - seems to be worth one point overall.

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Black got sente, and so takes the opportunity to strengthen his formation in the left centre.

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White starts the endgame on the left side of the board with Yamada Shinji's Tsuke, ...

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... followed by KataGo's Immediate Crosscut.

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In between, KataGo likes fixing the borders of White's upper right corner, starting with the peep at the upper edge.

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Black must connect, of course.

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Black is still par with the Punishment Semeai Liberty Level, and so forced to follow White with the Main Semeai.
He captures White's two stones in the lower left, so compensating for his territorial loss in the upper right corner.

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White ereases her remaining potential weakness in the upper right corner.

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Thereafter, White returns to the upper left corner.

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

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Black plays tenuki after White's atari, as usual.

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Cheng's Bump in the left centre.

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The Main Semeai continues.

Black must not play any reductionl

Just before her decision point, White will connect her single stone at the upper edge with . Black will force with for at the top, before occupying the last valuable point of in the right centre.

If she mistakenly waited until after her decision point, Black would not sacrifice the additional stone at in the Semeai Variation, so gaining one point.

Capture Variation:

Compared to the superordinate variation, ...

• Black's cumulated gain in the upper left is two points.
• In the upper right corner, White captured an additional Black stone, but lost two points of territory, so the net effect is zero.
• White captured Black's stone in the lower left, so gaining two points.
• Black destroyed one point of White's territory in the right centre.

In total, Black gained one point.

White + 7 => White + 6

Semeai Variation:

Compared to the superordinate variation, ...

• Black's cumulated gain in the upper left is two points.
• In the upper right corner, White captured an additional Black stone, but lost two points of territory, so the net effect is zero.
• White captured Black's stone in the lower left, so gaining two points.
• White captured one Black stone more in the right centre, so gaining one point.

In total, Black lost one point.

Jigo => White + 1

2024

2022MainLine

2022MainLine