:: Igo Hatsuyôron 120 (2021)

Variations of Our Solution (Ib)

KataGo's 2021 Solution

VAR (.2)

: ( 58ai)
Black descends to the upper edge.

We inserted this alternative move manually. The sequence below shows KataGo's favoured continuation (in "Analysis Mode").

:
White captures Black's stone in the lower left as a kikashi, ...

:
... before attacking Black's upper left corner, starting with the hane at .

:
Black tries to separate White's forces in the corner.

:
White's atari at the left edge is absolute sente.

:
Black must connect solidly.

He is unable to fight the ko after blocking with , instead.

:
White intends to establish an eye space for her group that is as large as possible.

:
Black's descent to the upper edge stops White from getting two eyes in the corner.

:
White destroys Black's potential second eye at the upper edge.

:
KataGo plays the atari at the nakade as a kikashi in-between.

KataGo also considered in the upper left and the peep at at the upper edge (both CHITOOM).

:
Black's group has only one eye.

:
KataGo seems to like playing kikashi like this.

:
White continues with the attack in the upper left corner, ...

:
... before answering Black's move in the upper right.

:
Black captures White's two stones at the left edge.

:
White recaptures.

:
Black plays atari from the outside.

KataGo also considered the throw-in at , instead.

:
White connects, preventing a Black throw-in at this point.

:
Black erases some potential White ko threats in the left centre.

:
Black captures at the left edge, starting a ko fight for life and death in the corner.

:
White captures the nakade as a ko threat.


Ko:

:
White splits the Nakade Sequence, in order to create an additional ko threat at the left.

:
The ko in the upper left corner is an approach-move ko, so Black throws-in at the left edge, erasing White's potential ko-threats in the nakade.

:
White occupies another outside liberty of Black's corner group.

:
White continues with occupying Black's outside liberties.

:
Black connects the ko.

:
White occupies the last outside liberty of Black's group, turning the upper left corner into a seki.

:
Black saves his hasami-tsuke stone that was in atari.

:
White continues with the endgame in the lower left corner.

:
Black connects, as there is no larger point available on the board.

:
White captures the hanezeki's tail.

:
Black recaptures.

:
White's oki continues a well-known sequence for dissolving the hanezeki.

:
White starts the endgame at the rest of the board.

...

Capture Variation:

Compared to the super²ordinate variation, ...

  • White's cumulated gain in the upper left corner is 17 points.
  • White's cumulatead gain in the left centre is one point.
  • Black's cumulated gain at the left edge is five points.
  • White destroyed two points of Black's territory in the lower left corner.
  • White did not capture Black's stone in the lower left, so losing two points.
  • Black's cumulated gain at the top is two points.
  • Black's cumulated gain at the right side of the board is ten points.

In total, White gained one point.

White + 2 => White + 3

Copyright © 2021 Thomas Redecker.

Design by Jan van Rongen, modified by Thomas Redecker.

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