:: Igo Hatsuyôron 120 (2021)

Variations of Our Solution (IIIb)

Tricking KataGo (Triple-Ko)

VAR (C) (A) (.2) (.2) (.1)

(.1)

: ( 222ce)
White plays hane at the upper edge, setting the scene for a ko fight in the upper left corner.

: (124 222dj)
Black gives atari in the upper left corner.

He might consider capturing at in the upper right, instead, but will be unable to gain decisively by this move.

:
White connects her stone in atari at the right, also erasing a potential Black ko threat.

:
Black starts the ko.


Ko: ; ;

:
This ko is an approach-move ko for White, and so seems to be disadvantageous for her.
But she is able to utilise Main Semeai moves as ko threats - contrary to Black - which will become sufficient compensation.

:
Black protects his territory in the left centre.

:
White recaptures the ko "early".

As we know now, she could have gained an even better result, if she continued with the Main Semeai first, thereby erasing Black's ko threats against her groups in the centre and the upper right.
Please refer to one of the appropriate subvariations for White before - but which were created after this one.

:
White captures the nakade.


Ko: ; ; ; ; ; ;

:
White is ready to capture the hanezeki's tail, and so can split the Nakade Sequence to generate additional ko threats.

We ask for your kind understanding that we did not colour the boards' edges during the course of the ensuing ko fights.

:
Black's connection allows White to connect at , but erases an important White ko threat.

:
Sooner or later, Black will run out of valid ko threats.

:
White makes sure that Black will not capture her stones in the corner.

:
Black cannot reach more than a seki in the corner now, and so has to answer White's threat, in order to secure a second eye for his upper group.

:
White's hasami-tsuke will damage Black's territory in the lower left corner.

:
But the value of the ko in the upper right corner is much larger than that, so Black connects the ko.

:
White's atari is larger than the connection at .

:
White prepares the scene for a larger ko threat to come.

:
White starts a short ko fight in the lower left.

:
Black does not have any viable ko threat, and so has to connect.

:
White ends the final ko fight.

Black plays 2/2 reductions.

Due to the seki in the upper left corner, White will choose the Capture Variation.

AfterWhite's decision point, and are miai.

Capture Variation:

Compared to the superordinate variation ...

  • Black got an additional point of territory in the left centre.
  • White did not capture Black's stone in the lower right, so losing two points.
  • White's cumulated gain in the lower left corner is nine points.

In total, White gained six points.

White + 6 => White + 12

Copyright © 2021 Thomas Redecker.

Design by Jan van Rongen, modified by Thomas Redecker.

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