At the beginning of the year, Dany introduced his atekomi to us, which leads to Dany's Ko.

In the context of this ko, we began our investigations into what effect it would have if Black did without his kikashi beforehand, especially after Joachim's idea to tenuki at the very beginning (instead of playing KataGo's solid connection).

Joachim discovered the value of White's kikashi in the lower left corner.

A few months later, Dany found that White's atari (played after her wedge in the left centre) should not be played so early, but kept in reserve as a ko threat.
However, for a long time we mistakenly thought that this atari was an additional ko threat for White, simplifying the ko fight for her (see also below).

Dany also found that (especially in conjunction with an earlier White move in the hanezeki that pre-empts Black's kikashi there) White might be able to gain decisively by not connecting her two stones in the lower right. We called this "Dany's Sacrifice".

It was a big shock when I noticed that we had taken the order of moves of several exchanges (especially with "natural" looking moves) too easy, not considering their effect on the number of Black's Main Semeai Liberties at the moment of White's decision point (when she hs to choose between Capture, and Semeai, Variation).
That was the starting point of my colour coding of the board edges (please refer to the respective legend below), making the status of the Main Semeai Liberties easily recognizable even in earlier stages of the game.

In this context, and in conjunction with Dany's atekomi, Joachim found that Black's atari at White's two stones in the lower left should be played very early. IF White connected (i.e. refuted Dany's Sacrifice), Black would gain two Main Semeai Liberties (what would remove some of his restrictions).

Joachim introduced his Final Ko in the Semeai Variation, but only as a side note. During my further investigations on this subject, it turned out that its application cases were far more numerous than Joachim had assumed.

Some special cirumstances given, Joachim's Final Ko will make it impossible for White to win the Semeai Variation if Black's large group has "only" nine Main Semeai Liberties (surely you will know already the Black's group survives the Semeai Variation with ten Main Semeai Liberties).

Joachim found another mistake in the order of moves, related to the number of Black's Main Semeai Liberties. If Black is par with the Punishment Semeai Liberty Level, he must not play his push at the top. White will continue with the Main Semeai thereafter, winning the Punishment Semeai.

When working on the presentation of Dany's atekomi and the following Dany's Ko without White's atari in the left centre having been played beforehand, I realised that White's atari was not an additional ko threat. Black still has his atari at White's two stones in the lower right to be used as a ko threat, compensating for White's atari in the centre.
Dany's atekomi loses one tempo in the Main Semeai in the abovementioned case, so that Black is then able to start Dany's Ko immediately.

Darkgrey = 6 Main Semeai Liberties:
Black has fallen below the Punishment Semeai Liberty Level. White will choose the Capture Variation, capturing not only the hanezeki's tail, but also Black's large group int he upper right.

Darkred = 7 Main Semeai Liberties:
Black is bound to follow the Main Semeai, as he must not lose a single tempo in the Main Semeai. Black can play outside the Main Semeai area, only if White did so just before.

Brown = 8 Main Semeai Liberties:
Under certain cirumstances (depending on the number of territory reducing moves Black has to play to get a satisfactory score in the Capture Variation), White must be careful to not lose a single tempo in the Main Semeai, and so might be restricted in her movements on the baord.

Pink = 9 Main Semeai Liberties:
Under certain circumstances (and still nine Main Semeai Liberties at White's decision point), White might fall prey to Joachim's Final Ko in the Semeai Variation.

Lightgrey = 10 or more Main Semeai Liberties:
Under certain circumstances (and still nine Main Semeai Liberties at White's decision point), White might fall prey to Joachim's Final Ko in the Semeai Variation.
If Black still has ten Main Semeai Liberties at White's decision point, Black's large group in the upper right will survive the Semeai Variation, resulting in White losing the game by a very large margin.

Lightbrown:
Capture Variation.

Darkbrown:
Semeai Variation.

Cyan:
Analysis mode. Special restrictions apply (e.g. a ban on giving atari at Black groups, or capturing Black groups that are in atari).

No Early Kikashi

For your convenience, a SGF of the above position for download.