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Tsumegos from real games
http://www.lifein19x19.com/viewtopic.php?f=15&t=17076
Page 3 of 4

Author:  Harleqin [ Fri Nov 20, 2020 2:19 pm ]
Post subject:  Re: Tsumegos from real games

Q18 seems to make miai.

Author:  jlt [ Wed Dec 09, 2020 7:45 am ]
Post subject:  Re: Tsumegos from real games

Problem #12, Black to play. It seems that Black can kill and that both players (1k Tygem) missed that during all the game.

Click Here To Show Diagram Code
[go]$$Bc Black to play
$$ ---------------------------------------
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . O . . . . . . . . . O . . . . . |
$$ | . . . , O . . . . , . . . . . X . . . |
$$ | . . X . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . X . . . . . . . . . . . . . . . . |
$$ | . . . O . . . . . . . . . . . . . . . |
$$ | . . O , . . . . . , . . . . . , . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . O . . . . . . . . . . . |
$$ | . . . . . . . O X . . . . . . . . . . |
$$ | . . O . . . . O X . . . . . . . . . . |
$$ | . O O . . . . O X . X X X . . . X . . |
$$ | . X X O O O O X X , O . O X . , . . . |
$$ | X . . X O X X O . O . . O O X X . . . |
$$ | . X X X X X . O . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ ---------------------------------------[/go]


Answer:

Click Here To Show Diagram Code
[go]$$Bc
$$ ---------------------------------------
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . O . . . . . . . . . O . . . . . |
$$ | . . . , O . . . . , . . . . . X . . . |
$$ | . . X . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . X . . . . . . . . . . . . . . . . |
$$ | . . . O . . . . . . . . . . . . . . . |
$$ | . . O , . . . . . , . . . . . , . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . O . . . . . . . . . . . |
$$ | . . . . . . . O X . . . . . . . . . . |
$$ | . . O . . . . O X . . . . . . . . . . |
$$ | . O O . . . . O X . X X X . . . X . . |
$$ | . X X O O O O X X , O 1 O X . , . . . |
$$ | X . . X O X X O . O . 2 O O X X . . . |
$$ | . X X X X X . O . . 3 . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ ---------------------------------------[/go]

Author:  jlt [ Fri Dec 11, 2020 10:48 am ]
Post subject:  Re: Tsumegos from real games

Problem #13: Black to play and kill the bottom group.

Click Here To Show Diagram Code
[go]$$Bc Black to play
$$ ---------------------------------------
$$ | . . . X . . . . . . . . . X O O . O . |
$$ | . . X O O O . . O X . . . X O . O O X |
$$ | . . X O . . O X O . X . . X X O O X . |
$$ | . . O X O O . O . , . . . X X X X . X |
$$ | . . X X . . . . . X O . O X O . . X . |
$$ | . . . X X X O . . . . O X O O . . . . |
$$ | . . X O O O X X X . O . X X . O X . . |
$$ | . X . X . X O X . O O X X . . O . O . |
$$ | . O X X X O O X X X O O X . . . O . . |
$$ | . . O O O O . O X X O . O X . , . . . |
$$ | . . . . . . . O O X X O O X . . . . . |
$$ | . . . . O X X X O O O . O X . . O . . |
$$ | . . O . . O . . X O O . O X . . O O . |
$$ | . . . . . O X . X X O O X . X X O X . |
$$ | . . . . . O X . . O X X X X . . X X . |
$$ | . . . O O X . . . O . . . . X X O O . |
$$ | . O O X X X . . X . O X X O . X . . . |
$$ | . . X . . . . . X O . O O . O X X . . |
$$ | . . . . . . . . O . . . . . . O . . . |
$$ ---------------------------------------[/go]


Answer:
Click Here To Show Diagram Code
[go]$$Bc Answer
$$ ---------------------------------------
$$ | . . . X . . . . . . . . . X O O . O . |
$$ | . . X O O O . . O X . . . X O . O O X |
$$ | . . X O . . O X O . X . . X X O O X . |
$$ | . . O X O O . O . , . . . X X X X . X |
$$ | . . X X . . . . . X O . O X O . . X . |
$$ | . . . X X X O . . . . O X O O . . . . |
$$ | . . X O O O X X X . O . X X . O X . . |
$$ | . X . X . X O X . O O X X . . O . O . |
$$ | . O X X X O O X X X O O X . . . O . . |
$$ | . . O O O O . O X X O . O X . , . . . |
$$ | . . . . . . . O O X X O O X . . . . . |
$$ | . . . . O X X X O O O . O X . . O . . |
$$ | . . O . . O . . X O O . O X . . O O . |
$$ | . . . . . O X . X X O O X . X X O X . |
$$ | . . . . . O X . . O X X X X . . X X . |
$$ | . . . O O X . . . O . . . . X X O O . |
$$ | . O O X X X . . X 1 O X X O . X . . . |
$$ | . . X . . . . . X O . O O . O X X . . |
$$ | . . . . . . . . O . . . . . . O . . . |
$$ ---------------------------------------[/go]

Author:  jlt [ Mon Jan 11, 2021 1:35 am ]
Post subject:  Re: Tsumegos from real games

This ridiculous position is from a blitz game.

Problem #14: Black to play. Which group should Black choose to kill and how?

Click Here To Show Diagram Code
[go]$$Bc Black to play
$$ ---------------------------------------
$$ | . . . . . . . . . . . . . . . X . . . |
$$ | . . O . . . . . . . . O . . X . X O . |
$$ | . X X O O O . . . . . . . X X . X O . |
$$ | . . . X X X O O O O . O . . . X O O . |
$$ | . . . . . . X X X O . . . . . X X O . |
$$ | . . . . . . . . . . . . . . . X O O . |
$$ | . . . . . X . . X . . . . . . . X . . |
$$ | . . . . . X O . . . . . . . . . . . . |
$$ | . . . X X O . . . X . . . . O O . . . |
$$ | . . X O O . O . O O X . . X O X . . . |
$$ | . . . . . . . . . . X . X X X O O . . |
$$ | . . X . . . O . . O X X O O X X O . . |
$$ | . . . . X O O . . . X O O . O X O . . |
$$ | . . . . . X O X . . X O . O . X . . . |
$$ | . . X X . X X . . . X . . . . X O . . |
$$ | . . O , . O . . . , X O . O O X O . . |
$$ | . . . O . . . O . . X . O . X X O . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ ---------------------------------------[/go]


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


"a" kills a bigger group than "b".

Author:  jlt [ Sun Jan 17, 2021 9:35 am ]
Post subject:  Re: Tsumegos from real games

Problem #15: Black to play. What is the status of the lower right corner?

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


Click Here To Show Diagram Code
[go]$$Bc Ko
$$ | . X O X O X . X X . . . . . . X O O X |
$$ | . O O O X X . O X . X X O . O O X X . |
$$ | . . . . . . . O X O . . . . . . X X . |
$$ | . . . . X . X X O X X X X . O O O X . |
$$ | . . O O O . . . O O O O . X X X X O . |
$$ | . . X X O O O O . . . . . . . X O O . |
$$ | . . . . X X X O . . . . . . X O . 2 1 |
$$ | . . . . . . . . . . . . . . 3 . O . . |
$$ ---------------------------------------[/go]

Author:  jlt [ Sat Jan 30, 2021 10:22 am ]
Post subject:  Re: Tsumegos from real games

Problem #16, Black to play.

I was white playing an H9 game and killed the upper left corner. However, Black could have lived. How?

Click Here To Show Diagram Code
[go]$$Bc Black to play
$$ ---------------------------------------
$$ | . . . . . . . . O O X . . . . . . . . |
$$ | . O O . X X O . O X X . . . . . . . . |
$$ | X X X . X O . O X . . . . . X O O . . |
$$ | . O O X X O . . . X . . . X . X X O . |
$$ | O . . O X O . O X . . . . . . . X O . |
$$ | . O . . O X . O X . . . . . . X X X O |
$$ | . O . O O X . O X X . . . . . . X O . |
$$ | O . O . O . . O X . . . . . . . X O . |
$$ | . O X O . O . . O O X X . X . . X O . |
$$ | . X . X . . . . . X O X X O . X O . . |
$$ | . . X . . O . . . . O . O O X X O . . |
$$ | . . . . . O . X X . . O . . X O . . . |
$$ | . . . . X O X . O O O X X . X O O . . |
$$ | . . X . X X O . O X X . . . . X O . . |
$$ | . . . . X O O . X . . . . . . X X O . |
$$ | . . X X . . . . . X . . . X . X O . . |
$$ | . . X O . O . . O X . . . . . X O . . |
$$ | X X O O . . . . O X . . . . X O O . . |
$$ | . O . . . . . . . . . . . . . . . . . |
$$ ---------------------------------------[/go]

Author:  lightvector [ Sat Jan 30, 2021 11:42 am ]
Post subject:  Re: Tsumegos from real games

About problem 15 shape, one interesting thing to know, if we adjust the stones a little...

Click Here To Show Diagram Code
[go]$$Bc White status?
$$ | . . . , . . . . . , . . . O X X X X . |
$$ | . X X X . . O . . . . . . O O X X . . |
$$ | . X O X O X . X X . . . . . . X . X . |
$$ | . O O O X X . O X . X X O . O O X . . |
$$ | . . . . . . . O X O . . . . . . X . . |
$$ | . . . . X . X X O X X X X . O O X . . |
$$ | . . O O O . . . O O O O . X X X X . . |
$$ | . . X X O O O O . . . . . . . X O O . |
$$ | . . . . X X X O . . . . . . X O . . . |
$$ | . . . . . . . . . . . . . . . . O . . |
$$ ---------------------------------------[/go]


Now white is alive and there is no ko.

Click Here To Show Diagram Code
[go]$$Bc Exercise for the reader - white to live
$$ | . . . , . . . . . , . . . O X X X X . |
$$ | . X X X . . O . . . . . . O O X X . . |
$$ | . X O X O X . X X . . . . . . X . X . |
$$ | . O O O X X . O X . X X O . O O X . . |
$$ | . . . . . . . O X O . . . . . . X . . |
$$ | . . . . X . X X O X X X X . O O X . . |
$$ | . . O O O . . . O O O O . X X X X . . |
$$ | . . X X O O O O . . . . . . . X O O . |
$$ | . . . . X X X O . . . . . . X O . 2 1 |
$$ | . . . . . . . . . . . . . . 3 . O . . |
$$ ---------------------------------------[/go]


Although also it requires the marked spots to be free of black stones:

Click Here To Show Diagram Code
[go]$$Bc
$$ | . . . , . . . . . , . . . O X X X X . |
$$ | . X X X . . O . . . . . . O O X X . . |
$$ | . X O X O X . X X . . . . . . X . X . |
$$ | . O O O X X . O X . X X O . O O X C . |
$$ | . . . . . . . O X O . . . . . . X C . |
$$ | . . . . X . X X O X X X X . O O X C . |
$$ | . . O O O . . . O O O O . X X X X . . |
$$ | . . X X O O O O . . . . . . . X O O . |
$$ | . . . . X X X O . . . . . . X O . . . |
$$ | . . . . . . . . . . . . . . . . O . . |
$$ ---------------------------------------[/go]


To also prevent this sequence:

Click Here To Show Diagram Code
[go]$$Bc
$$ | . . . , . . . . . , . . . O X X X X . |
$$ | . X X X . . O . . . . . . O O X X . . |
$$ | . X O X O X . X X . . . . . . X . X . |
$$ | . O O O X X . O X . X X O . O O X C . |
$$ | . . . . . . . O X O . . . . . . X C . |
$$ | . . . . X . X X O X X X X . O O X C . |
$$ | . . O O O . . . O O O O . X X X X 4 5 |
$$ | . . X X O O O O . . . . . . . X O O . |
$$ | . . . . X X X O . . . . . . X O . 1 2 |
$$ | . . . . . . . . . . . . . . . . O 3 . |
$$ ---------------------------------------[/go]


Anyways, this means that the following push is very bad for white, because white's corner goes from alive to black being able to make a ko.

Click Here To Show Diagram Code
[go]$$Wc bad push
$$ | . . . , . . . . . , . . . O X X X X . |
$$ | . X X X . . O . . . . . . O O X X . . |
$$ | . X O X O X . X X . . . . . . X . X . |
$$ | . O O O X X . O X . X X O . O O X . . |
$$ | . . . . . . . O X O . . . . . . X . . |
$$ | . . . . X . X X O X X X X . O O X 2 . |
$$ | . . O O O . . . O O O O . X X X X 1 . |
$$ | . . X X O O O O . . . . . . . X O O . |
$$ | . . . . X X X O . . . . . . X O . . . |
$$ | . . . . . . . . . . . . . . . . O . . |
$$ ---------------------------------------[/go]

Author:  jlt [ Sat Jan 30, 2021 3:44 pm ]
Post subject:  Re: Tsumegos from real games

In fact you make me realize that Problem #15 is the tripod group with extra leg.

https://senseis.xmp.net/?TripodGroupWithExtraLeg

I had read this page before, but not carefully.

Author:  jlt [ Mon Feb 01, 2021 12:32 am ]
Post subject:  Re: Tsumegos from real games

Answer to problem #16:

Click Here To Show Diagram Code
[go]$$Bc Answer
$$ -------------------------
$$ | . 8 9 . 3 2 1 . O O X .
$$ | 5 O O 6 X X O 4 O X X .
$$ | X X X 7 X O . O X . . .
$$ | . O O X X O . . . X . .
$$ | O . . O X O . O X . . .
$$ | . O . . O X . O X . . .[/go]

Author:  jlt [ Sat Feb 06, 2021 2:24 pm ]
Post subject:  Re: Tsumegos from real games

Problem #17, White to play. What is the status of the black group Q7?

Click Here To Show Diagram Code
[go]$$Wc White to play
$$ ---------------------------------------
$$ | . X . . . . . . . . . . . . . . . . . |
$$ | O X O O . . . . . . . . . . . . . . . |
$$ | . O X O . . . . . . . O X X X . . . . |
$$ | O X X O . . . . X O . O X O . , X . . |
$$ | X X X O . . . O O . O X O O O X . X . |
$$ | . X O O . . . . . X . X X X O O X . . |
$$ | . . X . . . . . . . . X . X . O O . . |
$$ | . X . . . . . . X . X . X . X X O . . |
$$ | . . . . . . . . . . X X O O O O O . . |
$$ | . . O , . . . O . O X O O X . , . . . |
$$ | . . . . . . . . . . O O X . X . X . . |
$$ | . . . . . . . . . O O . O . . . . . . |
$$ | . . . . . . . . . . X O . X . X X . . |
$$ | . . . O . . . . . . . . O . X . X O . |
$$ | . O O . . . . X X . . . . . . X O . O |
$$ | . X X O . . . O . X . O . O O O O O . |
$$ | . . X O . O . . . . X O . O X X X . . |
$$ | X . X X O . . . . . . X X X . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ ---------------------------------------[/go]


Answer ?

This seems to be a ko.

Click Here To Show Diagram Code
[go]$$Wc
$$ ---------------------------------------
$$ | . X . . . . . . . . . . . . . . . . . |
$$ | O X O O . . . . . . . . . . . . . . . |
$$ | . O X O . . . . . . . O X X X . . . . |
$$ | O X X O . . . . X O . O X O . , X . . |
$$ | X X X O . . . O O . O X O O O X . X . |
$$ | . X O O . . . . . X . X X X O O X . . |
$$ | . . X . . . . . . . . X . X . O O . . |
$$ | . X . . . . . . X . X . X . X X O . . |
$$ | . . . . . . . . . . X X O O O O O . . |
$$ | . . O , . . . O . O X O O X . , . b . |
$$ | . . . . . . . . . . O O X . X . X . . |
$$ | . . . . . . . . . O O . O 1 2 . . a . |
$$ | . . . . . . . . . . X O . X . X X . . |
$$ | . . . O . . . . . . . . O . X . X O . |
$$ | . O O . . . . X X . . . . . 3 X O . O |
$$ | . X X O . . . O . X . O . O O O O O . |
$$ | . . X O . O . . . . X O . O X X X . . |
$$ | X . X X O . . . . . . X X X . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ ---------------------------------------[/go]


a and b are miai.

Author:  jlt [ Sun Apr 11, 2021 7:28 am ]
Post subject:  Re: Tsumegos from real games

An easy one, that both players missed.

Problem#18, White to play in the lower left corner.

Click Here To Show Diagram Code
[go]$$Wc
$$ | . . . . . . . . . . . . .
$$ | . . . . . . . O . . X . X
$$ | . . . . . . . . . O . . .
$$ | . X X X . . . O . . . . .
$$ | . . O X . X . X O . O O O
$$ | . O O , . . X . O O X X X
$$ | . X . O . O X O O X X O O
$$ | . . X . . O O X X X . X X
$$ | . . . . . . . . . . X . .
$$ ---------------------------[/go]


Wrong answer:

Click Here To Show Diagram Code
[go]$$Wc ko
$$ | . . . . . . . . . . . . .
$$ | . . . . . . . O . . X . X
$$ | . . . . . . . . . O . . .
$$ | . X X X . . . O . . . . .
$$ | 5 6 O X . X . X O . O O O
$$ | 4 O O , . . X . O O X X X
$$ | . X . O . O X O O X X O O
$$ | 2 . X 1 . O O X X X . X X
$$ | . 3 . . . . . . . . X . .
$$ ---------------------------[/go]


Correct answer:

Click Here To Show Diagram Code
[go]$$Wc Black is unconditionally dead
$$ | . . . . . . . . . . . . .
$$ | . . . . . . . O . . X . X
$$ | . . . . . . . . . O . . .
$$ | . X X X . . . O . . . . .
$$ | . . O X . X . X O . O O O
$$ | 1 O O , . . X . O O X X X
$$ | . X . O . O X O O X X O O
$$ | . . X 2 3 O O X X X . X X
$$ | . . . . . . . . . . X . .
$$ ---------------------------[/go]

Author:  jlt [ Wed Apr 14, 2021 12:02 pm ]
Post subject:  Re: Tsumegos from real games

Problem#19: not complicated but not my first instinct. White to play.

Click Here To Show Diagram Code
[go]$$Wc White to play
$$---------------------
$$ . . . . . . . . . . |
$$ . X X O . . . . . . |
$$ . X O . O . X X X . |
$$ , X O . X . O X O . |
$$ . . O . . . O O . . |
$$ X . . . . . . O . . |
$$ . . . . . . O . O . |
$$ . . . . . . . O X . |
$$ . . . . . . . X . . |
$$ , . . . . . , . . . |
$$ . . . . . . . X . . |[/go]

Author:  Knotwilg [ Thu Apr 15, 2021 2:20 am ]
Post subject:  Re: Tsumegos from real games

Click Here To Show Diagram Code
[go]$$Wc White to play
$$---------------------
$$ . . . . . . 9 6 3 . |
$$ . X X O . 1 . 7 8 a |
$$ . X O . O . X X X . |
$$ , X O . X . O X O 4 |
$$ . . O . . . O O 2 b |
$$ X . . . . . . O . 5 |
$$ . . . . . . O . O . |
$$ . . . . . . . O X . |
$$ . . . . . . . X . . |
$$ , . . . . . , . . . |
$$ . . . . . . . X . . |[/go]

Author:  jlt [ Tue Jun 01, 2021 7:59 am ]
Post subject:  Re: Tsumegos from real games

Problem #20: this one is easy but I hallucinated during the game. White to play.

Click Here To Show Diagram Code
[go]$$Wc White to play
$$ ---------------------------------------
$$ | . . . . . . . . . . O . . . . . . . . |
$$ | . . . . O X . . . O X O O O O . . O O |
$$ | . O X O . . . X O O X X X X X O O X . |
$$ | . O X O . . X . O X X . . . X X X X . |
$$ | . X O O X X . . O O . . O O O X . . X |
$$ | X . X O O O X X . . . . . O X X . X . |
$$ | . X . X O . O X . O . . . . . . O X . |
$$ | . . . X . . O X X O . . . O . . O O . |
$$ | . . . . . . O . . X O O . . . O . . . |
$$ | . . . , . . . . X , X . . . . , . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . X . . . . . . . . . . . . X X . . |
$$ | . . . . . . . . . . . . . . X . . X . |
$$ | . . . . . . . . . . . . . . . . O O . |
$$ | . . X . . . . . . . O . . . . X O . . |
$$ | . . . , O . . . . , . X . . . X O . . |
$$ | . X X O . . . O . X . . . . . X O . . |
$$ | . . O . . . . . X . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ ---------------------------------------[/go]


Answer:

Click Here To Show Diagram Code
[go]$$Wc Answer
$$ ---------------------------------------
$$ | . . . . . . . . . . O . . . . . . . . |
$$ | . . . . O X . . . O X O O O O . . O O |
$$ | . O X O . . . X O O X X X X X O O X 1 |
$$ | . O X O . . X . O X X . . . X X X X 5 |
$$ | . X O O X X . . O O . . O O O X 4 . X |
$$ | X . X O O O X X . . . . . O X X 3 X . |
$$ | . X . X O . O X . O . . . . . . O X 2 |
$$ | . . . X . . O X X O . . . O . . O O . |
$$ | . . . . . . O . . X O O . . . O . . . |
$$ | . . . , . . . . X , X . . . . , . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . X . . . . . . . . . . . . X X . . |
$$ | . . . . . . . . . . . . . . X . . X . |
$$ | . . . . . . . . . . . . . . . . O O . |
$$ | . . X . . . . . . . O . . . . X O . . |
$$ | . . . , O . . . . , . X . . . X O . . |
$$ | . X X O . . . O . X . . . . . X O . . |
$$ | . . O . . . . . X . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ ---------------------------------------[/go]


:w1: and :w3: may be interchanged.

Yes after several years of practice I still make confusions between real eyes and false eyes.

Author:  jlt [ Thu Jun 03, 2021 2:37 am ]
Post subject:  Re: Tsumegos from real games

Problem #21: White to play.

Killing is not very hard but White needs to pay attention to something.

Click Here To Show Diagram Code
[go]$$Wc White to play
$$ ---------------------------------------
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . O O . . . . . . . . . . . . O O O . |
$$ | . X O . . . O O X . X O O . O X O X X |
$$ | . X X O O O . X X , X O X . . X X X . |
$$ | . . . X . . . . X . X X O O O . . . X |
$$ | . . X . X X X . O X O O X X O X X X . |
$$ | . . . . . O . . . . . X . . . O O X O |
$$ | . . O . O . . O . O O X O . O . O O . |
$$ | . O . O . O . . . O X X . . O X O X . |
$$ | O . O X O X O O X X . . . O . X X . . |
$$ | . O X X O X . X . . . . . . . . . X . |
$$ | . . . . O X . X . X . X X O O X . . . |
$$ | . . . X X O . . . X . . O X . X O . . |
$$ | . . . . X O O . . O X . O X . X O . . |
$$ | . . . . . X O . . O X . O . . . O . . |
$$ | . . X , . X O . O X . . . O . , . . . |
$$ | . . . X . X O . O X X . X . . O . . . |
$$ | . . . . X O O . O O X . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ ---------------------------------------[/go]


Answer:

R8. The point is that Black loses the following capturing race:

Click Here To Show Diagram Code
[go]$$Wc Answer
$$ ---------------------------------------
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . O O . . . . . . . . . . . . O O O . |
$$ | . X O . . . O O X . X O O . O X O X X |
$$ | . X X O O O . X X , X O X . . X X X . |
$$ | . . . X . . . . X . X X O O O . . . X |
$$ | . . X . X X X . O X O O X X O X X X . |
$$ | . . . . . O . . . . . X . . . O O X O |
$$ | . . O . O . . O . O O X O . O . O O . |
$$ | . O . O . O . . . O X X . . O X O X . |
$$ | O . O X O X O O X X . . . O . X X . . |
$$ | . O X X O X . X . . . . . . . . . X . |
$$ | . . . . O X . X . X . X X O O X 1 . . |
$$ | . . . X X O . . . X . . O X . X O . . |
$$ | . . . . X O O . . O X . O X . X O . . |
$$ | . . . . . X O . . O X . O 6 0 9 O . . |
$$ | . . X , . X O . O X . . 7 O 2 4 5 . . |
$$ | . . . X . X O . O X X . X 8 3 O . . . |
$$ | . . . . X O O . O O X . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ ---------------------------------------[/go]


and then P7 is a connect-and-die.

Author:  jlt [ Fri Jun 11, 2021 3:24 am ]
Post subject:  Re: Tsumegos from real games

Problem #22, White to play. Does White need to protect the corner?

Click Here To Show Diagram Code
[go]$$Wc White to play
$$ | X X X X . . O O X
$$ | . O O X X X O X X
$$ | . . O X O O X . X
$$ | . O . O O O X . X
$$ | . . . O X X X . .
$$ --------------------[/go]


Answer:

If White plays elsewhere then Black can kill by ko.

Click Here To Show Diagram Code
[go]$$Bc
$$ | X X X X . . O O X
$$ | 3 O O X X X O X X
$$ | 4 . O X O O X . X
$$ | 5 O 2 O O O X . X
$$ | . 1 . O X X X . .
$$ --------------------[/go]

Author:  jlt [ Mon Jun 14, 2021 3:15 pm ]
Post subject:  Re: Tsumegos from real games

Position #23, Black to play. What is the status of the upper left corner?

Click Here To Show Diagram Code
[go]$$Bc Black to play
$$ ---------------------------------------
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . O . . . O . . . . . . . . . . . . . |
$$ | . X O O O X X . . . . O X . . . . X . |
$$ | . X X O O O X X . O O X X X . X . . X |
$$ | . . X X O O X . . . . O . . . . X X O |
$$ | . . X O O O O X . X O . O . O . O O O |
$$ | O O X X X O O X . X O . . . . . . . . |
$$ | . . O X O O X X . X O . . . . . . . . |
$$ | O O X X X X O . X . X O . . . . . . . |
$$ | . . X , O X O . . , X . . O . X . O . |
$$ | . O O . . O . . . . . . . . X . . . O |
$$ | . X O . . . O . . . . . O O O O O O X |
$$ | . X . O . . . . . . . . . X X X X X X |
$$ | . . X X O . . . . . . . . . . O O . . |
$$ | . X . X O . . . . . . . . . . O X . . |
$$ | . X X O . . . O . X . . . . . , X . . |
$$ | . X O . O . . O X . . . . X . X . . . |
$$ | . O O . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ ---------------------------------------[/go]


Edit: coincidence, it's one of the daily problems on the app Tsumego Pro.

Click Here To Show Diagram Code
[go]$$Bc Answer
$$ ---------------------------------------
$$ | . 3 . 5 . 2 7 . . . . . . . . . . . . |
$$ | 4 O 9 6 8 O 1 . . . . . . . . . . . . |
$$ | . X O O O X X . . . . O X . . . . X . |
$$ | . X X O O O X X . O O X X X . X . . X |
$$ | . . X X O O X . . . . O . . . . X X O |
$$ | . . X O O O O X . X O . O . O . O O O |
$$ | O O X X X O O X . X O . . . . . . . . |
$$ | . . O X O O X X . X O . . . . . . . . |
$$ | O O X X X X O . X . X O . . . . . . . |
$$ | . a X , O X O . . , X . . O . X . O . |
$$ | . O O . . O . . . . . . . . X . . . O |
$$ | . X O . . . O . . . . . O O O O O O X |
$$ | . X . O . . . . . . . . . X X X X X X |
$$ | . . X X O . . . . . . . . . . O O . . |
$$ | . X . X O . . . . . . . . . . O X . . |
$$ | . X X O . . . O . X . . . . . , X . . |
$$ | . X O . O . . O X . . . . X . X . . . |
$$ | . O O . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ ---------------------------------------[/go]


White takes the ko first but Black has a ko threat at "a", so both groups survive.

Author:  jlt [ Mon Sep 20, 2021 8:18 am ]
Post subject:  Re: Tsumegos from real games

Position #24, White to play.

Click Here To Show Diagram Code
[go]$$Wc White to play
$$ ---------------------------------------
$$ | . . X O O . . . . . . . . . . . . . . |
$$ | . . X X O . . . X X . . . . . X X O . |
$$ | . . . X O . O . . O X X X X X X O X . |
$$ | . . X , O . . O O , O O O O O O O O . |
$$ | . . . . X O X . . . . . . . . . O . . |
$$ | . . X . X O X X . . . . . . . . X X . |
$$ | . . . . X O O . . . X O O . . . . . . |
$$ | . O O O X . . O . X O O X X . X . X . |
$$ | . X X O X . . . . . . . . . . . X O . |
$$ | . X . X O O O O O , O O . X X X O . O |
$$ | . X . X O . X X X X X . O X O O O O . |
$$ | . X . X O . O O X . . . X O . . . . . |
$$ | . . X . . . O X . X . . X O . . . . . |
$$ | . . X X . . X X . . . . X O . . . . . |
$$ | . . O X . . . . . . . . . . . . . . . |
$$ | . . O , . . . . . , . . . . O O O O O |
$$ | . . . O . O . X . . O O O . O X X X O |
$$ | . . . . . . . . . . . X X X X . . . X |
$$ | . . . . . . . . . . . . . . . . . X . |
$$ ---------------------------------------[/go]


Answer:

Click Here To Show Diagram Code
[go]$$Wc Answer
$$ ---------------------------------------
$$ | . . X O O . . . . . . . . . . . . . . |
$$ | . . X X O . . . X X . . . . . X X O . |
$$ | . . . X O . O . . O X X X X X X O X . |
$$ | . . X , O . . O O , O O O O O O O O . |
$$ | . . . . X O X . . . . . . . . . O . . |
$$ | . . X . X O X X . . . . . . . . X X . |
$$ | . . . . X O O . . . X O O . 1 3 4 . 5 |
$$ | . O O O X . . O . X O O X X 2 X . X . |
$$ | . X X O X . . . . . . . . . . . X O . |
$$ | . X . X O O O O O , O O . X X X O . O |
$$ | . X . X O . X X X X X . O X O O O O . |
$$ | . X . X O . O O X . . . X O . . . . . |
$$ | . . X . . . O X . X . . X O . . . . . |
$$ | . . X X . . X X . . . . X O . . . . . |
$$ | . . O X . . . . . . . . . . . . . . . |
$$ | . . O , . . . . . , . . . . O O O O O |
$$ | . . . O . O . X . . O O O . O X X X O |
$$ | . . . . . . . . . . . X X X X . . . X |
$$ | . . . . . . . . . . . . . . . . . X . |
$$ ---------------------------------------[/go]

Author:  jlt [ Tue Sep 21, 2021 2:14 am ]
Post subject:  Re: Tsumegos from real games

Position #25, White to live.

Click Here To Show Diagram Code
[go]$$Wc
$$ ---------------------------------------
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . O . . . . . . . . . . . . X . . |
$$ | . . X O . . . . O . X . . X . X . X . |
$$ | . . X O . O O . . , . . . . X O X X . |
$$ | . . . O . X X O O X . . . . . O O O . |
$$ | . X . . X . . X X O . . . . . . . . . |
$$ | . . . X . . . X O O . . . . . . . . . |
$$ | . . . . . X X O X . . X O O O O . . . |
$$ | . . . X . . O O . . O O X X X X X . . |
$$ | . O O O O . O . O , O X . . . , . . . |
$$ | . X . . . . . . . O X X . . . . O X . |
$$ | . . X . X . X . X . O X . . . O X X . |
$$ | . . . . . . . . . . O X . . . O X . . |
$$ | . X . O . X X X O . O X . . . . O O . |
$$ | . X O . O . . O . . . . . . . . O X . |
$$ | . O . , . . O . . , . . . . . O . X O |
$$ | . . . O . . . . O . X . . X X X O O . |
$$ | . . . . . . . . . . . . . . . . X X . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ ---------------------------------------[/go]

Author:  kvasir [ Tue Sep 21, 2021 3:32 am ]
Post subject:  Re: Tsumegos from real games

Position #25, White to live.
Click Here To Show Diagram Code
[go]$$Wc
$$ ---------------------------------------
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . O . . . . . . . . . . . . X . . |
$$ | . . X O . . . . O . X . . X . X . X . |
$$ | . . X O . O O . . , . . . . X O X X . |
$$ | . . . O . X X O O X . . . . . O O O . |
$$ | . X . . X . . X X O . . . . . . . . . |
$$ | . . . X . . . X O O . . . . . . . . . |
$$ | . . . . . X X O X . . X O O O O . . . |
$$ | . . . X . . O O . . O O X X X X X . . |
$$ | . O O O O . O . O , O X . . . , . . . |
$$ | . X . . . . . . . O X X . . . . O X . |
$$ | . . X . X . X . X . O X . 9 . O X X . |
$$ | . . . . . . . . . . O X . . 4 O X . . |
$$ | . X . O . X X X O . O X . 3 2 5 O O . |
$$ | . X O . O . . O . . . 8 7 . 1 . O X . |
$$ | . O . , . . O . . , . . . . 6 O . X O |
$$ | . . . O . . . . O . X . . X X X O O . |
$$ | . . . . . . . . . . . . . . . . X X . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ ---------------------------------------[/go]


Hope this is correct :D

It was hard to see that :w5: allows the net at :w9: so I looked at a few moves before coming back to :w1:

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