: ( 58bc)
White connects her two stones in the lower left.

This early connection - which is not mandatory at all - is the game-deciding mistake.

White must never ever connect her two stones, as long as the position in the upper left corner is still open.
White should simply play the crosscut in the upper left corner just now and play this connection after Black's (correct) reply in the upper left corner.

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Black has to defend in the left centre.

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KataGo likes to play this hasami-tsuke in the lower left corner as a kikashi.

Here, however, White cannot gain any local advantage by this exchange, but has enhanced Black's eye shape in the corner unnecessarwedeily. In addition, after White has already connected her two stones in the left centre (), White will never get a chance to connect her stone to the outside.
Therefore, this move can be considered to be a technical mistake. It is simply superfluous.

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White's wedge in the left centre is another kikashi often choosen by KataGo.

However, it can also be considered a kind of technical mistake, as it enhances Black's eye shape in the left centre unnecessarily (and is a genuine mistake, if played too early; 58dr). In general, it should be simply left unplayed.
But here, after White's mistaken connection in the lower left and the destruction of all aji in the lower left corner, this move will not make a difference.

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Finally, White has to connect at the left edge.

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White returns to the upper left corner, following the course of the superordinate variation.

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White's connection terminates the sequence in the upper left corner.

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With the marked exchange played, KataGo favours the solid connection to defend Black's territory in the lower left corner.

Alternatively, Black might consider descending to , as in the superordinate variation. The final scores of the game would not be affected.

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Whife forces once in the lower left corner.

Alternatively, she could also push at .

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KataGo seems to like pushing into the bamboo joint as a kikashi.

However, this move can be considered a technical mistake, if played so early. White should simply do without.
After Black captured White's single stone with , he might benefit by one point in the Semeai Variation by turning the point of into an approach-move liberty of his right-hand group. This will happen if he has sufficient Main Semeai Liberties to spend for connecting at and .

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White forced for a second time in the lower left corner.

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Black captures White's stone at the second line.

However, it might have been preferable to capture the other White stone with , instead, leaving absolutely no aji to the left.

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White plays KataGo's bad-shape move in the left centre.

Alternatively, she might also consider connecting at , instead. Both points are miai.

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Black captures White's stone in the right centre.

By this move, Black gains two points locally, but loses only one tempo in the Main Semeai in return (please note that has become an approach-move liberty of his group). Therefore, the net effect of this capture is a gain of one point overall.

: ( B 58bj)
White attaches in the left centre.

She would benefit by two points in the Semeai Variation, if she reduced Black's upper left corner before, starting with .

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Black plays an unusual attachment in the left centre, but will be unable to capture White's just played stone.

It would have been simpler to connect at immediately.

: (C 58bk)
Black descends to the upper edge, defending his territory in the upper left.

Connecting his stone in atari, instead, would be a grave mistake.

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The Main Semeai continues.

Please note that the Central Semeai will not work for Black here, as his right-hand group has one outside liberty less than in the superordinate variation.

Black must not play any reduction.

After her decision point, White will capture at in the centre; Black will push at at the upper edge.

Capture Variation:

Compared to the super²ordinate variation, ...

• Black's cumulated gain in the upper left corner is one point.
• Black's cumulated gain at the upper edge is two points.
• White's cumulated gain in the left centre is five points.
• Black captured White's single stone in the right centre, so gaining two points.

In total, gains and losses compensate for each other.

White + 1 => White + 1

Semeai Variation:

Compared to the super²ordinate variation, ...

• Black's cumulated gain in the upper left corner is one point.
• Black's cumulated gain at the upper edge is two points.
• White's cumulated gain in the left centre is five points.
• The net effect of the different play in the upper right is zero.

In total, White gained two points.

Black + 7 => Black + 5