:: Igo Hatsuyôron 120 (2021)

Variations of Our Solution (IIIb)

Tricking KataGo (Triple-Ko)

VAR (C) (A) (.2)

(Referenced by 222mw; 222na)


: ( 222aa)
White's peep is an artful, well-timed probe. It destroys Black's intention to initiate Joachim's Ko-Semeai.

However, Black gets the opportunity to play the guzumi, which will slightly increase the overall result of the game in his favour.

: (111 222nx ; A 222ob)
Black is on his guard, and takes the opportunity to play the guzumi.

If he immediately connected with , he would not get the chance to play the guzumi later, so losing several points overall.

Protecting his cutting point at the upper edge indirectly with (having his intention in mind to initiate Joachim's Ko-Semeai here), however, would be a grave mistake.

: (111 222on)
White answers locally, as usual.

It will be a mistake for White to complicate the matter by cutting with , so letting Black live at the right after . We assume that White would lose some points overall.

:
Eventually, Black answers White's peep at the upper edge.

Capturing White's five stones in the upper left with , instead, is out of the question. Black would fall prey to the Punishment Semeai thereafter.

:
White continues with the Main Semeai, still keeping Black par with the Punishment Semeai Liberty Level.

:
Black is able to connect his hasami-tsuke stone, which is quite large.

:
Now, White connects her five stones in the upper left.

:
Black reinforces his corner.

White's connection was not sente, but created an approach-move liberty for her left-hand group. Therefore, Black is unable to play e.g. the large endgame move of at the lower edge.

:
White's push destroys two points of Black's territory, without losing a tempo in the Main Semeai.

:
White does not connect her two stones in the lower left, as several endgame spots at the left side are still open.


: ( A 222oo)
White continues with the Main Semeai.

However, she must not let Black defend his territory in the left centre, and so play the wedge in the left centre, instead.
She will benefit by one point overall.

:
White starts the endgame on the left side "early".

For White, it does not make sense to push again at at the left edge, as this move costs one tempo in the Main Semeai. Therefore, Black would get compensation in the upper right corner.
The same is true for White's third push to , after Black connected at after her second one.
This implies that Black will occupy White's liberty there with during the course of the mutual occupation of opponent's liberties.

Black must not play any reduction.

After her decision point, White will hane at .
Before the end of the game, Black will have to connect at .

Capture Variation:

Compared to the super²ordinate variation ...

  • White's cumulated gain in the upper left is seven points.
  • Black's cumulated gain in the upper right corner is seven points.
  • White's cumulated gain in the lower left is two points.
  • White did not capture Black's stone at the lower edge, so losing two points.

In total, gains and losses compensate for each other.

White + 2 => White + 2

Semeai Variation:

Compared to the super²ordinate variation ...

  • White's cumulated gain in the upper left is seven points.
  • Black's cumulated gain in the upper right corner is zero; he destroyed four points of White's territory, but White captured an additional two Black stones for a gain of also four points.
  • White's cumulated gain in the lower left is two points.
  • White did not capture Black's stone at the lower edge, so losing two points.
  • Black captured two additional White stones at the left, so gaining four points.

In total, White gained three points.

Black + 3 => Jigo

Copyright © 2021 Thomas Redecker.

Design by Jan van Rongen, modified by Thomas Redecker.

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