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Charming ancient problem

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Charming ancient problem

Posted: Thu Apr 21, 2011 10:45 am
by Bill Spight
Here is a charming tsumego from the ancient Chinese book, Shiqing Lu.

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


Enjoy! :)

Re: Charming ancient problem

Posted: Thu Apr 21, 2011 11:25 am
by Shaddy
Click Here To Show Diagram Code
[go]$$W White to play
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . X X X X . . . . . . . . |
$$ | . . . . . . X O O O O X . . . . . . . |
$$ | . . . , . . X O X 3 O X . X . , . . . |
$$ | . . . . X . X O X X O X . . . X . . . |
$$ | . . . X . O X O . . O X O O O X . . . |
$$ | . . . . . . O . . X X O 1 . 2 . . . . |
$$ ---------------------------------------[/go]


Black has no resistance left, I think.

Re: Charming ancient problem

Posted: Thu Apr 21, 2011 11:59 am
by Mnemonic
It doesn't looks so bad first but if you just play by instinct:
Click Here To Show Diagram Code
[go]$$W White to play
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . X X X X . . . . . . . . |
$$ | . . . . . . X O O O O X . . . . . . . |
$$ | . . . , . . X O X , O X . X . , . . . |
$$ | . . . . X . X O X X O X . . . X . . . |
$$ | . . . X . O X O 4 3 O X O O O X . . . |
$$ | . . . . . . O . 5 C C O 1 . 2 . . . . |
$$ ---------------------------------------[/go]

Click Here To Show Diagram Code
[go]$$B Black throws in at :b1: and your group dies
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . X X X X . . . . . . . . |
$$ | . . . . . . X O O O O X . . . . . . . |
$$ | . . . , . . X O X , O X . X . , . . . |
$$ | . . . . X . X O X X O X . . . X . . . |
$$ | . . . X . O X O X O O X O O O X . . . |
$$ | . . . . . . O . O . 1 O O . X . . . . |
$$ ---------------------------------------[/go]

Click Here To Show Diagram Code
[go]$$W :b4: seems to be key so let’s play it. But as far as I can tell \n :b4: ruins everything again.
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . X X X X . . . . . . . . |
$$ | . . . . . . X O O O O X . . . . . . . |
$$ | . . . , . . X O X , O X . X . , . . . |
$$ | . . . . X . X O X X O X . . . X . . . |
$$ | . . . X . O X O 3 . O X O O O X . . . |
$$ | . . . . . . O 4 . X X O 1 . 2 . . . . |
$$ ---------------------------------------[/go]

Click Here To Show Diagram Code
[go]$$W This is my :w3:. No matter what black does, eventually he has to play\n at both location at the same time
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . X X X X . . . . . . . . |
$$ | . . . . . . X O O O O X . . . . . . . |
$$ | . . . , . . X O X 3 O X . X . , . . . |
$$ | . . . . X . X O B X O X . . . X . . . |
$$ | . . . X . O X O . . O X O O O X . . . |
$$ | . . . . . . O . . X B O 1 . 2 . . . . |
$$ ---------------------------------------[/go]

Re: Charming ancient problem

Posted: Thu Apr 21, 2011 12:02 pm
by Horibe
Shaddy wrote:
Click Here To Show Diagram Code
[go]$$W White to play
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . X X X X . . . . . . . . |
$$ | . . . . . . X O O O O X . . . . . . . |
$$ | . . . , . . X O X 3 O X . X . , . . . |
$$ | . . . . X . X O X X O X . . . X . . . |
$$ | . . . X . O X O . . O X O O O X . . . |
$$ | . . . . . . O . . X X O 1 . 2 . . . . |
$$ ---------------------------------------[/go]


Black has no resistance left, I think.


This gives me a headache - but if I were black I would "resist" with the throw in on the left...not sure I see how white lives this way - you cannot make black connect...

Re: Charming ancient problem

Posted: Thu Apr 21, 2011 12:49 pm
by Horibe
After lengthy staring...a tip of the hat to Shaddy...

Re: Charming ancient problem

Posted: Thu Apr 21, 2011 12:59 pm
by tchan001
haha, shaddy, we studied this shiqinglu problem last august in one of our tsumego sessions in the L19 room.

Re: Charming ancient problem

Posted: Thu Apr 21, 2011 5:36 pm
by Shaddy
did we? wow, i had completely forgotten -but it seems i remembered the main idea, hehe

Re: Charming ancient problem

Posted: Thu Apr 21, 2011 7:10 pm
by ez4u
Mnemonic wrote:
It doesn't looks so bad first but if you just play by instinct:
Click Here To Show Diagram Code
[go]$$W White to play
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . X X X X . . . . . . . . |
$$ | . . . . . . X O O O O X . . . . . . . |
$$ | . . . , . . X O X , O X . X . , . . . |
$$ | . . . . X . X O X X O X . . . X . . . |
$$ | . . . X . O X O 4 3 O X O O O X . . . |
$$ | . . . . . . O . 5 C C O 1 . 2 . . . . |
$$ ---------------------------------------[/go]

Click Here To Show Diagram Code
[go]$$B Black throws in at :b1: and your group dies
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . X X X X . . . . . . . . |
$$ | . . . . . . X O O O O X . . . . . . . |
$$ | . . . , . . X O X , O X . X . , . . . |
$$ | . . . . X . X O X X O X . . . X . . . |
$$ | . . . X . O X O X O O X O O O X . . . |
$$ | . . . . . . O . O . 1 O O . X . . . . |
$$ ---------------------------------------[/go]

Click Here To Show Diagram Code
[go]$$W :b4: seems to be key so let’s play it. But as far as I can tell \n :b4: ruins everything again.
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . X X X X . . . . . . . . |
$$ | . . . . . . X O O O O X . . . . . . . |
$$ | . . . , . . X O X , O X . X . , . . . |
$$ | . . . . X . X O X X O X . . . X . . . |
$$ | . . . X . O X O 3 . O X O O O X . . . |
$$ | . . . . . . O 4 . X X O 1 . 2 . . . . |
$$ ---------------------------------------[/go]

Click Here To Show Diagram Code
[go]$$W This is my :w3:. No matter what black does, eventually he has to play\n at both location at the same time
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . X X X X . . . . . . . . |
$$ | . . . . . . X O O O O X . . . . . . . |
$$ | . . . , . . X O X 3 O X . X . , . . . |
$$ | . . . . X . X O B X O X . . . X . . . |
$$ | . . . X . O X O . . O X O O O X . . . |
$$ | . . . . . . O . . X B O 1 . 2 . . . . |
$$ ---------------------------------------[/go]


Click Here To Show Diagram Code
[go]$$W White wants to fill in around the Black stones in order to capture both groups with the single play at 9. In this case there is just enough time to do so after the exchange of 1 for 2
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . X X X X . . . . . . . . |
$$ | . . . . . . X O O O O X . . . . . . . |
$$ | . . . , . . X O X 3 O X . X . , . . . |
$$ | . . . . X . X O X X O X 8 6 4 X . . . |
$$ | . . . X . O X O 5 9 O X O O O X . . . |
$$ | . . . . . . O . 7 X X O 1 . 2 . . . . |
$$ ---------------------------------------[/go]


Click Here To Show Diagram Code
[go]$$W White can live by playing either point marked "a"
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . X X X X . . . . . . . . |
$$ | . . . . . . X O O O O X . . . . . . . |
$$ | . . . , . . X O . O O X . X . , . . . |
$$ | . . . . X . X O a . O X X X X X . . . |
$$ | . . . X . O X O O O O X O O O X . . . |
$$ | . . . . . . O . O . a O O . X . . . . |
$$ ---------------------------------------[/go]



Click Here To Show Diagram Code
[go]$$W Playing 3 (or "a") is the wrong order however. It lets Black remove the threat of making two eyes above by playing 4. So 3 at 4 is the only solution.
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . X X X X . . . . . . . . |
$$ | . . . . . . X O O O O X . . . . . . . |
$$ | . . . , . . X O X 4 O X . X . , . . . |
$$ | . . . . X . X O X X O X . . . X . . . |
$$ | . . . X . O X O 3 . O X O O O X . . . |
$$ | . . . . . . O . a X X O 1 . 2 . . . . |
$$ ---------------------------------------[/go]

Re: Charming ancient problem

Posted: Fri Apr 22, 2011 7:22 am
by Bill Spight
Congratulations to the solvers. ez4u's answer is the most detailed and thorough. :)

I have a perspective that is a bit different, and adds something, I think. :)

Click Here To Show Diagram Code
[go]$$W White threatens to make an eye and kills two stones
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . X X X X . . . . . . . . |
$$ | . . . . . . X O O O O X . . . . . . . |
$$ | . . . , . . X O X , O X . X . , . . . |
$$ | . . . . X . X O X X O X . . . X . . . |
$$ | . . . X . O X O . . O X O O O X . . . |
$$ | . . . . . . O . . B B O 1 a 2 . . . . |
$$ ---------------------------------------[/go]


I have always thought of plays like :w1: as threatening to make a eye. But there is another way to look at it, which is helpful here. :w1: make a half eye at "a". :b2: takes it away.

:w1: also makes a potential half eye when the :bc: stones are captured. But White needs two eyes to live. Where are the other eye and a half coming from?

Obviously, they have to come from capturing or killing the three other stones inside White's eye space. Just killing them is not enough, as that yields only one eye. But capturing three stones yields 1 1/2 eyes.

Click Here To Show Diagram Code
[go]$$W White prevents one eye
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . X X X X . . . . . . . . |
$$ | . . . . . . X O O O O X . . . . . . . |
$$ | . . . , . . X O X 3 O X . X . , . . . |
$$ | . . . . X . X O X X O X . . . X . . . |
$$ | . . . X . O X O . . O X O O O X . . . |
$$ | . . . . . . O . . X X O 1 . 2 . . . . |
$$ ---------------------------------------[/go]


White must be careful. If Black plays at 3, White can capture four stones, but the resulting four point square eye would only be a single eye, not an eye and a half. :w3: prevents Black from taking away a potential half eye.

Click Here To Show Diagram Code
[go]$$W White makes two eyes
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . X X X X . . . . . . . . |
$$ | . . . . . . X O O O O X . . . . . . . |
$$ | . . . , . . X O X 3 O X . X . , . . . |
$$ | . . . . X . X O X X O X 6 8 4 X . . . |
$$ | . . . X . O X O 5 9 O X O O O X . . . |
$$ | . . . . . . O . 7 X X O 1 . 2 . . . . |
$$ ---------------------------------------[/go]


White must still be careful, as the two eyes are only potential. If White plays :w9: before :w5: or :w7:, then he will make only 1 1/2 actual eyes when capturing one group of stones or the other. White must capture both at once to make two eyes.

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


1 1/2 + 1/2 = 2 eyes. :)


Here is a variation for Black.

Click Here To Show Diagram Code
[go]$$W Single eye space
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . X X X X . . . . . . . . |
$$ | . . . . . . X O O O O X . . . . . . . |
$$ | . . . , . . X O X 3 O X . X . , . . . |
$$ | . . . . X . X O X X O X . . 4 X . . . |
$$ | . . . X . O X O 5 6 O X O O O X . . . |
$$ | . . . . . . O . . X X O 1 . 2 . . . . |
$$ ---------------------------------------[/go]


:b6: connects to prevent two separate eye spaces for White.

Click Here To Show Diagram Code
[go]$$B No nakade
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . X X X X . . . . . . . . |
$$ | . . . . . . X O O O O X . . . . . . . |
$$ | . . . , . . X O . O O X . X . , . . . |
$$ | . . . . X . X O . . O X . . X X . . . |
$$ | . . . X . O X O O . O X O O O X . . . |
$$ | . . . . . . O . O 2 1 O O . X . . . . |
$$ ---------------------------------------[/go]


However, the resulting zigzag four eye shape is alive. Black has no nakade to kill.

------

Endgame considerations are not really part of tsumego, but still of some interest, I think.

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


After :w3: White is alive. Now the local temperature has dropped, and both players can play elsewhere.

Click Here To Show Diagram Code
[go]$$B Black plays first
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . X X X X . . . . . . . . |
$$ | . . . . . . X O O O O X . . . . . . . |
$$ | . . . , . . X O X O O X . X . , . . . |
$$ | . . . . X . X O X X O X 3 5 1 X . . . |
$$ | . . . X . O X O 2 6 O X O O O X . . . |
$$ | . . . . . . O . 4 X X O O . X . . . . |
$$ ---------------------------------------[/go]


Click Here To Show Diagram Code
[go]$$B Black captures 5 stones
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . X X X X . . . . . . . . |
$$ | . . . . . . X O O O O X . . . . . . . |
$$ | . . . , . . X O . O O X . X . , . . . |
$$ | . . . . X . X O 8 . O X X X X X . . . |
$$ | . . . X . O X O O O O X O O O X . . . |
$$ | . . . . . . O . O . 7 O O 9 X . . . . |
$$ ---------------------------------------[/go]


:b7: forces :w8:, and then :b9: captures five White stones.

Click Here To Show Diagram Code
[go]$$W White plays first
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . X X X X . . . . . . . . |
$$ | . . . . . . X O O O O X . . . . . . . |
$$ | . . . , . . X O X O O X . X . , . . . |
$$ | . . . . X . X O X X O X . . . X . . . |
$$ | . . . X . O X O 1 . O X O O O X . . . |
$$ | . . . . . . O . . X X O O . X . . . . |
$$ ---------------------------------------[/go]


:w1: saves the five stones.

Click Here To Show Diagram Code
[go]$$B One point Black sente
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . X X X X . . . . . . . . |
$$ | . . . . . . X O O O O X . . . . . . . |
$$ | . . . , . . X O X O O X . X . , . . . |
$$ | . . . . X . X O X X O X 3 . 1 X . . . |
$$ | . . . X . O X O O 4 O X O O O X . . . |
$$ | . . . . . . O . 2 X X O O . X . . . . |
$$ ---------------------------------------[/go]


Ignoring the plays on the left for convenience, Black has a one point sente on the right.

Click Here To Show Diagram Code
[go]$$B One point Black sente
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . X X X X . . . . . . . . |
$$ | . . . . . . X O O O O X . . . . . . . |
$$ | . . . , . . X O . O O X . X . , . . . |
$$ | . . . . X . X O 6 . O X X . X X . . . |
$$ | . . . X . O X O O O O X O O O X . . . |
$$ | . . . . . . O . O . 5 O O . X . . . . |
$$ ---------------------------------------[/go]
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