(Referenced by 58ar; 58bc; 58bd; 58bi; 58by; 58cr)

: ( 58ap)
White plays the wedge in the left centre, but which is the game-deciding mistake here.

White must never ever play this wedge before an atari at Black's nakade.
White will be unable to make up for having stabilised Black's shape in the left centre unnecessarily.
She does not have any chance to give the urgently needed atari at Black's nakade later.

:
Black gives atari from the outside, as usual.

:
Here, White gives counter-atari from above.

Giving atari from below, with a move at , would have the same effect. It's just a matter of a change in the order of moves.

:
Black's shape in the left centre has been stabilised by White unnecessarily.
The White cut at (an earlier exchange of for assumed) is no longer a valid threat.

:
KataGo likes to insert the hasami-tsuke in the lower left corner as a kikashi.

However, this move will increase the susceptibility to errors in the following course of the game unnecessarily (and can be a genuine mistake; 58by), and so can be considered to be a technical mistake in the timing of moves.

:
White plays another kikashi at the upper edge.

:
Last, but not least, captures White Black's stone in the lower left centre.

:
White continues with the Main Semeai, for just one move.

However, an exchange of liberty occupying moves of the Main Semeai is unnecessary at the moment, and so can be considered to be a technical mistake in the timing of moves.
White should simply do without this move.

: ( 122 58ds)
Black defends his upper left corner at the left edge, also occupying a liberty of White's group below.

He would gain two points in the Semeai Variation, if he defended in the left centre with first.

:
White plays the tsuke of Yamada Shinji Shinki quite "early".

:
The ensuing sequence ends with Black's atari at the upper edge.

:
White continues with the endgame at the lower edge.

: ( 122 58dt)
Black plays tenuki to defend his upper left corner.

He would gain two points in the Semeai Variation, if he defended in the left centre with first.

:
White inserts the final atari after her initial wedge in the left centre.

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

Please note that this move loses one tempo in the Main Semeai - in principle - as it does not contain an immediate local threat.

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

:
White inserts another kikashi in the lower left corner.

Please note that this kikashi is effective, only if White is able to deny Black's left-hand group any eye in the left centre.

: (A 58du)
Black answers from below, as usual.

Black does not have a sure eye in the left centre yet, but would be able to answer with the atari of from the left here, due to White's missing atari at the nakade. He would reach the same final scores of the game as with the sequence below.

: (A 58dv)
KataGo simply continued with the Main Semeai in this selfplay game.

This move was my first candidate for a potential mistake in this subvariation, as there are more valuable points remaining on the board. White's move prevents a Black push into her upper right corner, but which Black does not want to play so early anyway.
But after a closer inspection of the alternative continuation I had to admit that I was too hasty in the very beginning. The status of this move changed to "false positive".

Capturing with in the lower left corner instead, completing the endgame sequence at the bottom, would not affect the overall result of the game.

If Black now connects at , and White connects at , the local score is zero.
White's left-hand group lost her liberty at ; Black has sente.

Therefore, Black is able to capture White's single stone in the upper right with . Compared to a White connection at , he gained one point locally.

Both sides lost two tempi each in the Main Semeai, so Black is still one over par with the Punishment Semeai Liberty Level.
Black will play another territory destroying move, gaining two points in the Capture Variation in total.

Please note that White cannot achieve the usual benefit of one point by playing the kikashi at (while keeping Black without any eye in the left centre) here.
Black would not connect at , usually his best reply, but simply give atari at White's corner stones with .
This was the deciding fact that I had overlooked in the very beginning.

If Black now captures two White stones with , and White captures one Black stone with , the local score will be two points for Black.
Again, White lost her liberty at , but she has sente now.

In principle, she will use her sente to prevent a one-point-reduction of her territory in the upper right, e.g. with - so gaining one point.

Additionally, White did not lose any further tempo in the Main Semeai, so Black still has one Main Semeai Liberty to spend.
Again, Black will benefit by two points in the Capture Variation in total.

If White (with her move ) captures at and connects at thereafter, the local score will be two points for White.
Black has sente.

In principle, he will use his sente to destroy one point of White's territory in the upper right by capturing White's single stone with .

Thereafter, Black is three over par with the Punishment Semeai Libery Level, so he will be able to destroy another three points of White's territory.
In total, Black gained two points in the Capture Variation again.

Please note that White cannot achieve the usual benefit of one point by playing the kikashi at (while keeping Black without any eye in the left centre) here.
Black would not connect at , usually his best reply, but simply give atari at White's corner stones with .
This was the deciding fact that I had overlooked in the very beginning.

: ( 128 58dy)
Black captures White's two stones in the lower left

Alternatively, he might consider connecting his stone in atari. The overall result of the game would not be affected, but Black would benefit by two points in the Semeai Variation.

:
White captures Black's single stone at the bottom.

:
White must connect her single stone in the right centre.

:
White must give atari at Black's nakade stones.

Otherwise, she would lose her stones at the left after Black's atari at . A move at would be too late then, due to .

:
Black is able to insert his kikashi at the top, ...

:
... before playing KataGo's solid connection in the left centre.

Black must not play any reduction.

After her decision point, White will connect at at the upper edge.

Capture Variation:

Compared to the superordinate variation, ...

• Black's cumulated gain in the upper left corner is two points.
• White's cumulated gain at the top is four points.
• White destroyed one point of Black's territory in the left centre.

In total, White gained three points.

Black + 2 => White + 1

Semeai Variation:

Compared to the superordinate variation, ...

• Black's cumulated gain in the upper left corner is two points.
• White's cumulated gain at the top is four points.
• White destroyed one point of Black's territory in the left centre.
• Black captured an additional White stone in the left centre, so gaining two points.

In total, White gained one point.

Black + 2 => Black + 1