:: Igo Hatsuyôron 120 (2021)

Variations of Our Solution (Ib)

KataGo's 2021 Solution

VAR (.3) (.2)

: ( 58ar)
White continues with the Main Semeai.

:
White returns to the upper left centre.

:
White pushes at the left edge.

: ( 141 58au)
I took things too easy here with connecting at immediately.
Mistakenly, I thought that this connection would be simply a change in the order of moves, because Black would have to add a protective move in the corner anyway, before approaching White's left-hand group at .

However, I overlooked that the exchange of for is White's sente, reducing Black's corner by one additional point.

Black must block at , instead.

:
White pushes for a second time, in sente, punishing Black for his previous mistake.

:
White got this third push for free.
Compared to the superordinate variation, where White exchanged for before, White's third push at is sente here.

If it were gote, as in the superordinate variation, Black would be able to play an additional territory-destroying move (in the Capture Variation), compensating for his one-point loss in the upper left corner.

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

: ( 146 58av)
Black defends his territory in the left centre.

He would benefit in the Semeai Variation, if he played the descent to at the upper edge, while not affecting the overall result of the game.

: (A 58aw)
Black defends his upper left corner immediately, so taking profit outside the Main Semeai area.

He might continue with the Main Semeai, instead, but will lose two points in the Semeai Variation.

Black plays 3/3 reductions.

Capture Variation:

Compared to the superordinate variation, ...

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

In total, White gained one point.

White + 1 => White + 2

Semeai Variation:

Compared to the superordinate variation, ...

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

In total, White gained one point.

Black + 5 => Black + 4

Copyright © 2021 Thomas Redecker.

Design by Jan van Rongen, modified by Thomas Redecker.

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