Life In 19x19 :: The most difficult problem ever. Igo Hatsuyoron 120

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The most difficult problem ever. Igo Hatsuyoron 120 http://lifein19x19.com/viewtopic.php?f=17&t=4381	Page 4 of 4

Author:	Cassandra [ Sat Feb 08, 2025 1:48 pm ]
Post subject:	Re: The most difficult problem ever. Igo Hatsuyoron 120
RobertJasiek wrote: Sorry for playing the noob. Some trivial help below ... RobertJasiek wrote: Click Here To Show Diagram Code [go]$$Bm135 $$ +---------------------------------------+ $$ \| . . . . X . X O . . . O . O . . O X . \| $$ \| . . X 8 . X O . O O O X O . O . . O . \| $$ \| . X O O X X . O . . . X O O . O O . . \| $$ \| . X O X O X X 9 0 O . X . O O X . . . \| $$ \| X . X X O X O O O . O X X X X X O O . \| $$ \| O X . O O O X X X O . . X . X O X . . \| $$ \| O O O O X X O O X X O O O O X O . X . \| $$ \| O X . X . X . O O X O . . . X X X X X \| $$ \| O X . X . . . O X X O . X X X X O O O \| $$ \| 2 O O X . X . O X O O X X O O O O X . \| $$ \| 1 4 O O X . . O X O . X O O O . X X X \| $$ \| 5 3 O O X . . O X O . X O O X X X O O \| $$ \| 7 . O O X . . O X O . X O O O X X X O \| $$ \| . O O X . X . O X O . X X O O O X O O \| $$ \| 6 O X . X X . O X O X . O X X X O O O \| $$ \| O X X X X X . O X O O O O X O X O O X \| $$ \| O . . . O X O O X X X X X T O X X O X \| $$ \| O . X . X O . O O O O O O X O X . O X \| $$ \| . X . . X O O O . . . . O X X X . O . \| $$ +---------------------------------------+[/go] Why would 36 at 41 fail? Variation 1: Black plays 37 at 36. White's cut-off group above is left with only two liberties. In principle, White will have to capture the Hanezeki's Tail with (otherwise, Black will connect there in Sente), so losing several points from the repeated capture of Black's Nakade at the left edge. Otherwise, if White takes liberty of Black's two stones, Black will throw-in at 40, leaving White with a two-point-eye only. This loses her several Main-Semeai-Liberties (not to mention the captured Black stones), so White would have to capture the Tail later. Variation 2: Black throws-in at 40. This means that White has lost the capture of the five-point Nakade, i.e. Black stones and Main-Semeai-Liberties as well. White's capture of the Tail might come later than in variation 1, but still in vain. RobertJasiek wrote: Click Here To Show Diagram Code [go]$$Bm155 $$ +---------------------------------------+ $$ \| . . . X X . X O . . . O . O . . O X . \| $$ \| . . X . X X O . O O O X O . O . . O . \| $$ \| . X . . X X . O . . 8 X O O . O O . . \| $$ \| . X . X O X X X O O O X . O O X O . . \| $$ \| X . X X O X O O O . O X X X X X O O . \| $$ \| O X X O O O X X X O . O X . X O X 4 b \| $$ \| O O O O X X O O X X O O O O X O . X . \| $$ \| O X 7 X . X . O O X O . O . X X X X X \| $$ \| O X 5 X . 3 . O X X O 6 X X X X O O O \| $$ \| O O O X . X 2 O X O O X X O O O O X . \| $$ \| X O O O X . . O X O . X O O O . X X X \| $$ \| X X O O X . . O X O . X O O X X X O O \| $$ \| X 1 O O X . . O X O . X O O O X X X O \| $$ \| 0 O O X . X . O X O O X X O O O X O O \| $$ \| O O X . X X . O X O X a O X X X O O O \| $$ \| O X X X X X . O X O O O O X O X O O X \| $$ \| O X . . O X O O X X X X X . O X X O X \| $$ \| O X X . X O . O O O O O O X O X . O X \| $$ \| 9 X . . X O O O . . . . O X X X . O . \| $ +---------------------------------------+[/go] Why does White postpone dissolution of the hane-seki as long as possible? White will dissolve the hane-seki, why does he play all the approach moves in the upper right? White wants to (repeatedly) capture as many stones in the Nakade as possible. Capturing the Hanezeki's Tail is Sente for White. However, this means that White thereafter has ONLY ONE move for free. If there remained more than one open spot into her territory in the centre, and the upper right, Black would destroy some White territory and win. EDIT: After this diagram, Black will play three Gote moves inside the Nakade. At the right, there are two valueable spots left (a and b), so White has sufficient opportunity to fill these. If the Semeai-Variation were best for White, to order of White's liberty-taking moves at the right would not matter at all.

Author:	dany [ Sat Feb 15, 2025 7:41 am ]
Post subject:	Re: The most difficult problem ever. Igo Hatsuyoron 120
Cassandra wrote: For some of these non-Main-Semeai variations, it seems to have been consolidated in the meantime that they represent valid solutions to the problem. I will publish details on this in subsequent posts. Does these non-Main-Semeai variations really matter? If non-Main-Semeai variations better for White then Black force Main-Semeai variation https://igohatsuyoron120.de/2015/0009f.htm "81 blocks the upper left corner. Black could have enforced the "usual" 2022 Solution by inserting the Guzumi A prior to any of the marked moves in the centre (White would be forced to answer locally at B." If non-Main-Semeai variations better for Black then White will choose Main-Semeai variation at move 82 So in any case Main-Semeai will be choosen not non-Main-Semeai variations

Author:	Cassandra [ Sun Feb 16, 2025 12:58 am ]
Post subject:	Re: The most difficult problem ever. Igo Hatsuyoron 120
dany wrote: So in any case Main-Semeai will be choosen not non-Main-Semeai variations Really? The further course of the Main Semeai does NOT match the historical meaning of the title of the problem given by Inoue Dôsetsu Inseki.

Author: Cassandra [ Sat Mar 15, 2025 4:16 am ]

Post subject: Re: The most difficult problem ever. Igo Hatsuyoron 120

The other non-Main-Semeai variations

The other non-Main-Semeai variations still have a long way to go before consolidation, as the board is much emptier / more open and there are therefore many more variations to investigate.

8 generations of the 28b-net after #59 ...

+ + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + +

046048_F2J3

Click Here To Show Diagram Code: [go]$$B $$ +---------------------------------------+ $$ | . . . . . . . . . . . . X . . . O X . | $$ | . . . . . . . X O O . X O X O . . O . | $$ | . . . . . X . O . . . X O . . O O . . | $$ | . X O , . . . . . O . X . O O X . . . | $$ | . . X X . X . . . . O X X . X X O O . | $$ | . X . O . O . . . . . . X . X O . . . | $$ | . O O O . . O O . . O O . O X . . Y . | $$ | O . . X . . . . . . . . . . X X X X X | $$ | . . . X . . . O . . O . X X X X O O O | $$ | X O O , . X . . . O . X X O O O O X . | $$ | X . . O X . . . . O . X O O O . X X X | $$ | X . . O X . . . X O . X O O X X X O O | $$ | X X . . X . . O . O . X O O O X X X O | $$ | . O O X O X . . . O . X X O O O X O O | $$ | . . X . . X . . . a X . O X X X O O O | $$ | O X X , X . . O . O O O O X O X O O X | $$ | . . . . O X B . W X X X X . O X X O X | $$ | O . X . . Q . . O O O O O X O X . O X | $$ | . X . . . . . . . . . . O X X X . O . | $$ +---------------------------------------+[/go]

Really seems to come down to Jigo.
However, the question of whether :bc:

is actually the best answer to :wt:

still needs to be clarified.
:bc:

does not seem to be the best answer to :wt:

. The push at a, instead, makes the game easier for Black.
The jûrokubango is still to come.

046_J3

Click Here To Show Diagram Code: [go]$$Bc $$ +---------------------------------------+ $$ | . . . . . . . . . . . . X . . . O X . | $$ | . . . . . . . X O O . X O X O . . O . | $$ | . . . . . X . O . . . X O . . O O . . | $$ | . X O , . . . . . O . X . O O X . . . | $$ | . . X X . X . . . . O X X . X X O O . | $$ | . X . O . O . . . . . . X . X O . . . | $$ | . O O O . . O O . . O O . O X . . Y . | $$ | O . . X . . . . . . . . . . X X X X X | $$ | . . . X . . . O . . O . X X X X O O O | $$ | X O O , . X . . . O . X X O O O O X . | $$ | X . . O X . . . . O . X O O O . X X X | $$ | X . . O X . . . X O . X O O X X X O O | $$ | X X . . X . . O . O . X O O O X X X O | $$ | . O O X O X . . . O . X X O O O X O O | $$ | . . X . . X . . . . X . O X X X O O O | $$ | O X X , X . . O . O O O O X O X O O X | $$ | . . . . O X . . Q X X X X . O X X O X | $$ | O . X . . . . . O O O O O X O X . O X | $$ | . X . . . . . . . . . . O X X X . O . | $$ +---------------------------------------+[/go]

Seems to be a bit easier for Black than for White.
The jûrokubango is still to come.

046_F2

Click Here To Show Diagram Code: [go]$$Bc $$ +---------------------------------------+ $$ | . . . . . . . . . . . . X . . . O X . | $$ | . . . . . . . X O O . X O X O . . O . | $$ | . . . . . X . O . . . X O . . O O . . | $$ | . X O , . . . . . O . X . O O X . . . | $$ | . . X X . X . . . . O X X . X X O O . | $$ | . X . O . O . . . . . . X . X O . . . | $$ | . O O O . . O O . . O O . O X . . Y . | $$ | O . . X . . . . . . . . . . X X X X X | $$ | . . . X . . . O . . O . X X X X O O O | $$ | X O O , . X . . . O . X X O O O O X . | $$ | X . . O X . . . . O . X O O O . X X X | $$ | X . . O X . . . X O . X O O X X X O O | $$ | X X . . X . . O . O . X O O O X X X O | $$ | . O O X O X . . . O . X X O O O X O O | $$ | . . X . . X . . . a X . O X X X O O O | $$ | O X X , X . . O . O O O O X O X O O X | $$ | . . . . O X . . . X X X X . O X X O X | $$ | O . X . . Q . . O O O O O X O X . O X | $$ | . X . . . . . . . . . . O X X X . O . | $$ +---------------------------------------+[/go]

Easier for Black than for White.
A move at a seems to be an interesting option for Black now.

044_K3

Click Here To Show Diagram Code: [go]$$Bc $$ +---------------------------------------+ $$ | . . . . . . . . . . . . . . . . O X . | $$ | . . . . . . . X O O . X O . W W . O . | $$ | . . . . . X . O . . . X Y . . B O . . | $$ | . X O , . . . . . O . X . O O B . . . | $$ | . . X X . X . . . . O X X . X X O O . | $$ | . X . O . O . . . . . . X . X O . @ . | $$ | . O O O . . O O . . O O . O X . . # . | $$ | O . . X . . . . . . . . . . X X X X X | $$ | . . . X . . . O . . O . X X X X X O O | $$ | X O O , . X . . . O . X X O O O O O . | $$ | X . . O X . . . . O . X O O O . X X X | $$ | X . . O X . . . X O . X O O X X X O O | $$ | X X . . X . . O . O . X O O O X X X O | $$ | . O O X O X . . . O . X X O O O X O O | $$ | . . X . . X . . . . X . O X X X O O O | $$ | O X X , X . . O . O O O O X O X O O X | $$ | . . . . O X . . . Q X X X . O X X O X | $$ | O . X . . . . . O . O O O X O X . O X | $$ | . X . . . . . . . . . . O X X X . O . | $$ +---------------------------------------+[/go]

Easier for Black than for White.

040_K3

Click Here To Show Diagram Code: [go]$$Bc $$ +---------------------------------------+ $$ | . . . . . . . . . . . . . . . . O X . | $$ | . . . . . . . X O O . X O . . . . O . | $$ | . . . . . X . O . . . X . . . W O . . | $$ | . X O , . . . . . O . X . O O B . . . | $$ | . . X X . X . . . . O X X . X X O O . | $$ | . X . O . O . . . . . . X . X O . . . | $$ | . O O O . . O O . . O O . O X . . Y . | $$ | O . . X . . . . . . . . . . X X X X X | $$ | . . . X . . . O . . O . X X X X O O O | $$ | X O O , . X . . . O . X X O O O O X . | $$ | X . . O X . . . . O . X O O O . X X X | $$ | X . . O X . . . X O . X O O X X X O O | $$ | X X . . X . . O . O . X O O O X X X O | $$ | . O O X O X . . . O . X X O O O X O O | $$ | . . X . . X . . . . X . O X X X O O O | $$ | O X X , X . . O . O O O O X O X O O X | $$ | . . . . O X . . . Q X X X . O X X O X | $$ | O . X . . . . . O . O O O X O X . O X | $$ | . X . . . . . . . . . . O X X X . O . | $$ +---------------------------------------+[/go]

Easier for White than for Black.
False positive!
BOTH nets usually win with White.

036_L3

Click Here To Show Diagram Code: [go]$$Bc $$ +---------------------------------------+ $$ | . . . . . . . . . . . . . . . . O X . | $$ | . . . . . . . X O O . X O . . . . O . | $$ | . . . . . X . O . . . X . . . . O . . | $$ | . X O , . . . . . O . X . O O , . . . | $$ | . . X X . X . . . . O X X . X X O O . | $$ | . X . O . O . . . . . . X . X O . . . | $$ | . O O O . . O O . . O O . O X . . Y . | $$ | O . . X . . . . . . . . . . X X X X X | $$ | . . . X . . . O . . O . X X X X O O O | $$ | X O O , . X . . . O . X X O O O O X . | $$ | X . . O X . . . . O . X O O O . X X X | $$ | X . . O X . . . X O . X O O X X X O O | $$ | X X . . X . . O . O . X O O O X X X O | $$ | . O O X O X . . . O . X X O O O X O O | $$ | . . X . . X . . . . X . O X X X O O O | $$ | O X X , X . . O . , O O O X O X O O X | $$ | . . . . O X . . . . Q X X . O X X O X | $$ | O . X . . . . . O . O O O X O X . O X | $$ | . X . . . . . . . . . . O X X X . O . | $$ +---------------------------------------+[/go]

Seems to come down to Jigo.

036_F2

Click Here To Show Diagram Code: [go]$$Bc $$ +---------------------------------------+ $$ | . . . . . . . . . . . . . . . . O X . | $$ | . . . . . . . X O O . X O . . . . O . | $$ | . . . . . X . O . . . X . . . . O . . | $$ | . X O , . . . . . O . X . O O , . . . | $$ | . . X X . X . . . . O X X . X X O O . | $$ | . X . O . O . . . . . . X . X O . . . | $$ | . O O O . . O O . . O O . O X . . Y . | $$ | O . . X . . . . . . . . . . X X X X X | $$ | . . . X . . . O . . O . X X X X O O O | $$ | X O O , . X . . . O . X X O O O O X . | $$ | X . . O X . . . . O . X O O O . X X X | $$ | X . . O X . . . X O . X O O X X X O O | $$ | X X . . X . . O . O . X O O O X X X O | $$ | . O O X O X . . . O . X X O O O X O O | $$ | . . X . . X . . . . X . O X X X O O O | $$ | O X X , X . . O . , O O O X O X O O X | $$ | . . . . O X . . . . . X X . O X X O X | $$ | O . X . . Q . . O . O O O X O X . O X | $$ | . X . . . . . . . . . . O X X X . O . | $$ +---------------------------------------+[/go]

Probably a "false positive".
BOTH nets win a lot of games with Black.
The jûrokubango is still to come.

012_O5

Click Here To Show Diagram Code: [go]$$Bc $$ +---------------------------------------+ $$ | . . . . . . . . . . . . . . . . O X . | $$ | . . . . . . . X O O . X O . . . . O . | $$ | . . . . . X . O . . . X . . . . O . . | $$ | . X O , . . . . . O . X . O O , . . . | $$ | . . X X . X . . . . O X X . X X O O . | $$ | . X . O . O . . . . . . X . X O . . . | $$ | . O O O . . O O . . O O . O X . . . . | $$ | O . . X . . . . . . . . . . X X X X X | $$ | . . . X . . . O . . O . X X X X . O O | $$ | X O O , . X . . . O . X . O O O O Y . | $$ | X . . O X . . . . O . X . . O . X X X | $$ | X . . O X . . . X O . X O O X X X O O | $$ | X X . . X . . O . O . X O . . . X X O | $$ | . O O X O X . . . O . . X O O . . O O | $$ | . . X . . X . . . . X . . Q X X O O O | $$ | O X X , X . . O . , O O O . O X O . X | $$ | . . . . O X . . . . . . . . . X X O X | $$ | O . X . . . . . O . . . O X O X . O . | $$ | . X . . . . . . . . . . O X X X . . . | $$ +---------------------------------------+[/go]

Easier for Black than for White.

011_O8

Click Here To Show Diagram Code: [go]$$Bc $$ +---------------------------------------+ $$ | . . . . . . . . . . . . . . . . O X . | $$ | . . . . . . . X O O . X O . . . . O . | $$ | . . . . . X . O . . . X . . . . O . . | $$ | . X O , . . . . . O . X . O O , . . . | $$ | . . X X . X . . . . O X X . X X O O . | $$ | . X . O . O . . . . . . X . X O . . . | $$ | . O O O . . O O . . O O . O X . . . . | $$ | O . . X . . . . . . . . . . X X X X X | $$ | . . . X . . . O . . O . X X X X . O O | $$ | X O O , . X . . . O . X . O O O O . . | $$ | X . . O X . . . . O . X . . O . . X X | $$ | X . . O X . . . X O . X O Y . X X O O | $$ | X X . . X . . O . O . X O . . . X X O | $$ | . O O X O X . . . O . . X O O . X O O | $$ | . . X . . X . . . . X . . X X X O O O | $$ | O X X , X . . O . , O O O . O X O Q X | $$ | . . . . O X . . . . . . . . . X X O X | $$ | O . X . . . . . O . . . O X O X . O . | $$ | . X . . . . . . . . . . O X X X . . . | $$ +---------------------------------------+[/go]

Seems to be a bit easier for Black than for White.
The jûrokubango is still to come.

010_O5

Click Here To Show Diagram Code: [go]$$Bc $$ +---------------------------------------+ $$ | . . . . . . . . . . . . . . . . O X . | $$ | . . . . . . . X O O . X O . . . . O . | $$ | . . . . . X . O . . . X . . . . O . . | $$ | . X O , . . . . . O . X . O O , . . . | $$ | . . X X . X . . . . O X X . X X O O . | $$ | . X . O . O . . . . . . X . X O . . . | $$ | . O O O . . O O . . O O . O X . . . . | $$ | O . . X . . . . . . . . . . X X X X X | $$ | . . . X . . . O . . O . X X X X . O O | $$ | X O O , . X . . . O . X . O O O O Y . | $$ | X . . O X . . . . O . X . . O . X X X | $$ | X . . O X . . . X O . X O . . X X O O | $$ | X X . . X . . O . O . . . . . . X X O | $$ | . O O X O X . . . O . . X O O . X O O | $$ | . . X . . X . . . . X . . Q X X O O O | $$ | O X X , X . . O . , O O O . O X O O X | $$ | . . . . O X . . . . . . . . . X X O X | $$ | O . X . . . . . O . . . O X O X . O . | $$ | . X . . . . . . . . . . O X X X . . . | $$ +---------------------------------------+[/go]

Seems to be a bit easier for Black than for White.
The jûrokubango is still to come.

009_N9

Click Here To Show Diagram Code: [go]$$Bc $$ +---------------------------------------+ $$ | . . . . . . . . . . . . . . . . O X . | $$ | . . . . . . . X O O . X O . . . . O . | $$ | . . . . . X . O . . . X . . . . O . . | $$ | . X O , . . . . . O . X . O O , . . . | $$ | . . X X . X . . . . O X X . X X O O . | $$ | . X . O . O . . . . . . X . X O . . . | $$ | . O O O . . O O . . O O . O X . . . . | $$ | O . . X . . . . . . . . . . X X X X X | $$ | . . . X . . . O . . O . X X X X . O O | $$ | X O O , . X . . . O . X . O O O O . . | $$ | X . . O X . . . . O . X Y . O . . X X | $$ | X . . O X . . . X O . X O . X X X O O | $$ | X X . . X . . O . O . X O . . . X X O | $$ | . O O X O X . . . O . . X Q O . . O O | $$ | . . X . . X . . . . X . . . X X O O O | $$ | O X X , X . . O . , O O O . O X O . X | $$ | . . . . O X . . . . . . . . . X X O X | $$ | O . X . . . . . O . . . O X O X . O . | $$ | . X . . . . . . . . . . O X X X . . . | $$ +---------------------------------------+[/go]

Probably a "false positive".
BOTH nets win a lot of games with Black.
The jûrokubango is still to come.

008_O5

Click Here To Show Diagram Code: [go]$$Bc $$ +---------------------------------------+ $$ | . . . . . . . . . . . . . . . . O X . | $$ | . . . . . . . X O O . X O . . . . O . | $$ | . . . . . X . O . . . X . . . . O . . | $$ | . X O , . . . . . O . X . O O , . . . | $$ | . . X X . X . . . . O X X . X X O O . | $$ | . X . O . O . . . . . . X . X O . . . | $$ | . O O O . . O O . . O O . O X . . . . | $$ | O . . X . . . . . . . . . . X X X X X | $$ | . . . X . . . O . . O . X X X X . O O | $$ | X O O , . X . . . O . X . O O O O Y . | $$ | X . . O X . . . . O . X . . O . X X X | $$ | X . . O X . . . X O . X O . . X X O O | $$ | X X . . X . . O . O . . . . . . X X O | $$ | . O O X O X . . . O . . X O O . . O O | $$ | . . X . . X . . . . X . . Q X X O O O | $$ | O X X , X . . O . , O O O . O X O . X | $$ | . . . . O X . . . . . . . . . X X O X | $$ | O . X . . . . . O . . . O X O X . O . | $$ | . X . . . . . . . . . . O X X X . . . | $$ +---------------------------------------+[/go]

Seems to be a bit easier for Black than for White.
The jûrokubango is still to come.

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