(Referenced by 58aa; 58ai; 58dc)

: ( 58bb)
Black defends his formation in the left centre by playing this guzumi.

However, this move is the game-deciding mistake here (correct continuation below provided), compensating for White's earlier mistake of having connected at too early.

Black's defensive move in the left centre does not occupy a liberty of White's left-hand group, and so loses one decisive tempo in the Main Semeai.

Contrary to a subvariation discussed later ( 58dc), Black's upper left corner is still open here. However, Black's loss of one Main Semeai Liberty will make the inside atari after White's forthcoming crosscut mandatory, losing one point overall.

:
White captures the nakade.

:
KataGo likes to insert the wedge in the left centre early.

:
White erases Black's potential for creating one point of territory by playing at this point himself.

; :
KatoGo seems to like this exchange.

:
White returns to the upper left corner.

: (A 58cu)
Black answers White's crosscut with the inside atari.

Playing the outside atari of , instead, would be a mistake here, due to Black's earlier move at in the centre that cost him a decisive tempo in the Main Semeai.

:
White returns to the upper left corner.

:
KataGo likes to insert this exchange.

(Referenced by 58aa)

:
Black descends to the lower edge, defending his territory in the lower left corner, instead of blocking with , doing the same with the upper left corner.

Please remember that this choice benefits White by four points in the Semeai Variation (correct continuation below provided), while not affecting the overall result of the game.

:
White continues in the upper left corner, following a well-known path.

:
White plays the final atari in the left centre in-between.

:
Black captures White's stone in the right centre.

: ( 143 58cv)
White closed the remaining hole in the border of her upper right corner.
However, there was no need to do so, as Black will not push into her corner territory anyway.

This move will increase the susceptibility to errors in the following course of the game unncessarily, and so can be considered to be a technical mistake in the timing of moves.

White should play the wedge in the right centre first, in sente.
Quite contrary to the "usual" preference of AI to insert kikashi early (assumed to reduce the complexity of the game for the programmes), which can also be seen above, KataGo missed an important one here.

:
Black secures an additional point of territory in the right centre.

If he played at the left side of the board, instead, it would result a change in the order of moves with the previous subvariation.

In order to defend her potential territory in the upper right, White needed four moves ().

Black needed five moves () to accomplish the same task at the left side of the board.

It's White's turn, so after all defensive moves were played in order, there would remain one hole in the encirclement of Black's territories.

Please note that both sides already played one protective move each in the upper right.

Please also note that Black is unable to connect his stone in the lower right, as this would lose two tempi in the Main Semeai - but he has none to spend.

White has five territory-destroying moves at the left side of the board (), all gaining one point (in the Capture Variation).

Black would be able to destroy four points of White's territory in the upper right, and has the connection of in the lower right at his hands, which is worth two points.

This implies that White must never start the mutual reduction of opponent's territory.
If she did, Black would be able to connect , so gaining one point overall.

:
White occupies one of Black's liberties at the right, also defending her potential territory at the top.

:
Black returns the favour with a protecting move in the lower left corner.

: ( A 58cw)
Simply occupying a Black liberty with a move that does not cover any hole in White's borders in the upper right is a grave mistake, which will decide the game in Black's favour.

White must continue e.g. with , instead.

White's mistake seems to be similar to another line, where White mistakenly did not capture Black's stone in the lower left corner, but thoughtlessly occupied one of Black's liberties at the right.
However, the mistake her follows another systematic; it's just an error in the order of the mutual occupation of opponent's liberties.

:
Black continues with the Main Semeai, playing his protective moves first.

Black must not play any reduction.

Capture Variation:

Compared to the superordinate variation, ...

• Black's cumulated gain in the upper left corner is three points.
• White's cumulated gain at the upper edge is five points,
• Black got an additional point of territory in the left centre.
• Black did not capture one White stone there, so losing two points.
• Black captured White's single stone in the right centre, so gaining three points.

In total, gains and losses compensate for each other.

White + 1 => White + 1

Semeai Variation:

Compared to the superordinate variation, ...

• Black's cumulated gain in the upper left corner is three points.
• White's cumulated gain at the upper edge is five points,
• Black got an additional point of territory in the left centre.
• Black did not capture one White stone there, so losing two points.
• Black captured two White stones less in the upper left, so losing four points.
• White captured one Black stone more in the upper right, so gaining two points.
• Black destroyed one point of White's territory in the upper right corner.

In total, White gained eight points.

Black + 7 => White + 1