:: Igo Hatsuyôron 120 (2015)

Technical Notes (III)

The chapters "Technical Notes" are designed especially for those who are more interested in the problem, or even want to investigate it on their own. All others can skip these chapters without disadvantage.

In principle, the final decision on the outcome of the game is already fallen. Therefore, it only remains to draw attention to some special points.


This continues the "Technical Notes (II)" from 195.


The First Genuine Gote Move 495
The Tsuke of Yamada Shinji 6p 496
The Hanezeki Exchange 496
Surrender of the Atari in the Nakade 497
Territory-Destroying Options are Evenly Distributed 497
Order of Moves for Filling the Nakade 498
Choice Between Capture and Semeai Variation 499
The Oki of Joachim Meinhardt 501

The First Genuine Gote Move

Tec III.1:

completes the nine-stone nakade on the left edge. However, this move does not contain a direct threat against any of 's partial groups . Therefore, there is no need for to answer this move locally, e.g. by capturing . Further information on this subject can be found later ( 831).

The Tsuke of Yamada Shinji 6p

Tec III.2:

The top left corner is the largest open space on the board. The tsuke , kindly shown to us by Yamada Shinji 6p, starts the endgame. In principle, this move can be played at any time - as long as capturing the hanezeki's tail , with a move at , is possible for W. gains one point locally - compared to the "classical" move one point to the right - and additionally changes some sente-gote-relationship of the problem as a whole, which can lead to a further gain of a second point.


Yamada's tsuke is discussed in the sections "2007 - A New Move - Tsuke" ( 787), "2011 - Yamada's Tsuke Again" ( 794), and "Yamada Shinji's Tsuke" ( 879).

The Hanezeki Exchange

Tec III.3:

The Hanezeki Exchange of / must be played at the right moment. If played too early, a potential ko-threat would be given away. If waited for too long, could pre-empt this exchange with a move at 95 herself, gaining additional profit when choosing the Semeai Variation later, with a move at .


Without the second throw-in , a move at 95 is double-sente, so must play the Hanezeki Exchange very "early".


The atari of destroys one point of 's potential territory, at 94, and is coupled with the second throw-in .



White will not answer the atari in the Hanezeki ( 566a).

Harry Fearnley found that playing the forcing moves Black and in the Hanezeki just after Yamada's Tsuke in the upper left corner (; chosen by us for no specific reason) is the wrong timing.

Black must play this exchange earlier in the game!

Surrender of the Atari in the Nakade

Tec III.4:

A technical matter that could become important, if it were not this problem (and especially, if had less liberties), is the question, whether should give atari in the nakade or not. We decided to continue with occupying liberties in the top right, with a move at , preferring an "unconditional" continuation. The alternate atari in the nakade would in principle create a ko-shape, but which is quite irrelevant in this problem, because has no chance to win the resulting ko.


This issue is discussed in the section "2012 - White's Unforced Atari in the Nakade" ( 822).

Territory-Destroying Options are

Evenly Distributed

Tec III.5:

If we consider both sides options for reducing their opponent's territory, we can identify six dotted points of 's / 's potential territory in the left / right half of the board that could be destroyed by / . However, destroying one point of territory is strongly coupled with losing an own liberty in the Main Semeai, which enables the opponent to return the favour. Therefore, a mutual reduction of territories will not affect the final score. Please see also "2012 - Occupying White's Liberties" ( 833).

Order of Moves for Filling the Nakade

Tec III.6:

Another technical matter that could become important, if it were not this problem, is the correct order of moves for filling the nakade. According to Ōhashi Hirofumi 6p, should not use the dotted point (to avoid a triangled four-point nakade), but play - as shown here, to get a squarish shape.

Tec III.6a:

After captured with , is dead as it stands. With the triangled nakade, would be forced to play oki with , to pre-empt two eyes for .


However, in the problem, has no use for his "just won" sente, because he has to take another liberty, with reference to the Main Semeai.


Further information can be found in the section "2012 - Correct Order of Moves for Filling a Nakade" ( 820).

Choice Between Capture and Semeai Variation

(Referenced by 37)


Tec III.7:

After played into the nakade for the last time, with , has to choose between the Semeai Variation (starting with a move at ), and the Capture Variation (starting with a move at ).


In the Semeai Variation, captures 3 stones on the lower edge (and later gets 1 stone plus 3 points of territory there), captures 3 stones in the nakade, and 3 stones in the lower right, captures (14 stones plus 14 points of territory), captures (33 stones and 34 points of territory), gets on the left (28 stones and 29 points of territory).


has got a total of 92 points, has got a total of 73 points (i.e. 19 points for so far). wins the Semeai Variation by 3 points, so has a plus of 16 points in the rest of the board.


In the Capture Variation, captures (20 stones plus 18 points of territory), re-captures 4 stones, captures 3 stones in the lower right, captures / (14 / 18 stones plus 14 / 18 points of territory), captures 1 stone on the lower edge, and gets 1 stone plus 4 points of territory in the nakade.


has got a total of 68 points, has got a total of 47 points. With 21 points for far this is 2 points worse for than the Semeai Variation.

Tec III.7a:

We now can admire that the problem has been composed exactly such that - from 's point of view - 's group in focus () is one stone too small, and each of 's groups in focus (//) is one stone too large. If the hanezeki's tail were one stone longer, and all of 's above-mentioned groups were one stone smaller, would win both variations by one point.

Tec III.8:

However, it is in no case easy to try adjusting the problem, in an attempt to giving support to .


It seems that is might be possible to make smaller by one stone, through changing the stone at the marked spot into a one. But this action is coupled to two side-effects. On the one hand, the assumption that has got an initial prisoner before the problem starts, can no longer be maintained - this reduces 's gain to one point. On the other hand, there are now 71 , but only 70 stones on the board - this makes a further adjustment necessary.

Tec III.8a:

might be an appropriate addition of 's 71st stone, hopefully not affecting any of the problem's main sequences. However, this measure provides with an additional prisoner, reducing 's gain to zero.


To cut a long story short, we think that it is best to stick to the original.

The Oki of Joachim Meinhardt

Tec III.9:

With the Capture Variation - after has captured the hanezeki's tail, and has recaptured with a move at - everything is played out on the board already, but only one spot remains for the final endgame:


Joachim Meinhardt's oki at in the lower right corner.


On the one hand, this oki forces to take , and , off the board, but what must have done anyway, because his large group in the upper right lacks eyes.


On the other hand - and this impact is much more decisive - allows to capture in sente, gaining at least four points locally.


During the development of the classical solution, this territorial effect - which would have won the game for - seems to have become lost out of sight. Now - with the knowledge of the guzumi , and the hasami-tsuke , in the upper right corner - this move - after which Joachim sought for so long - is part of a sub-variation of our solution "only". Nevertheless, this move has kept its very great importance.

Joachim's oki is discussed in detail in the chapter "The Decisive Moment in the Historical Line of Play" ( 877).

Copyright © 2017 Thomas Redecker.

Design by Jan van Rongen, modified by Thomas Redecker.

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