Tsumego from a game. What's the status of black group in the upper left corner?
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[go]$$c This is a label for the diagram. $$ ------------------------------- $$ | . X O . . X . . . . . . . . $$ | X O O X X X O O O O . . . . $$ | . X . X O O X X X X O O . . $$ | O X X X O O O X . X O . O . $$ | . O O O . O X . X O O O . . $$ | . O . . O O X X X O . . . . $$ | . O O O . O O . . . . . . . $$ | . X X O X X O . . . . . . . $$ | . X O X . . X X . . . . . . $$ | . . . X X X . . . , . . . . $$ | . . . X . . . . . . . . . . $$ | . . . . . . . . . . . . . .[/go]
Re: Tsumego from a game
Posted: Thu Dec 23, 2010 9:09 pm
by Shaddy
B to play- alive, W to play- looks like 10k year ko.
Re: Tsumego from a game
Posted: Fri Dec 24, 2010 7:21 pm
by walleye
Shaddy wrote:
B to play- alive, W to play- looks like 10k year ko.
I would appreciate a diagram. I don't see a 10k year ko.
Re: Tsumego from a game
Posted: Fri Dec 24, 2010 7:50 pm
by ethanb
B first = alive W first = alive in seki
$$Wc This is also a diagram label. $$ ------------------------------- $$ | 4 X O 1 . X 5 . . . . . . . $$ | X O O X X X O O O O . . . . $$ | 2 X . X O O X X X X O O . . $$ | O X X X O O O X . X O . O . $$ | 3 O O O . O X . X O O O . . $$ | . O . . O O X X X O . . . . $$ | . O O O . O O . . . . . . . $$ | . X X O X X O . . . . . . . $$ | . X O X . . X X . . . . . . $$ | . . . X X X . . . , . . . . $$ | . . . X . . . . . . . . . . $$ | . . . . . . . . . . . . . .
[go]$$Wc This is also a diagram label. $$ ------------------------------- $$ | 4 X O 1 . X 5 . . . . . . . $$ | X O O X X X O O O O . . . . $$ | 2 X . X O O X X X X O O . . $$ | O X X X O O O X . X O . O . $$ | 3 O O O . O X . X O O O . . $$ | . O . . O O X X X O . . . . $$ | . O O O . O O . . . . . . . $$ | . X X O X X O . . . . . . . $$ | . X O X . . X X . . . . . . $$ | . . . X X X . . . , . . . . $$ | . . . X . . . . . . . . . . $$ | . . . . . . . . . . . . . .[/go]
There's also a more complicated variation where white captures inside and black takes outside, but it doesn't really do anything interesting - still seki unless I miss something.
Re: Tsumego from a game
Posted: Fri Dec 24, 2010 10:48 pm
by Shaddy
hmm, ethan is right.
Re: Tsumego from a game
Posted: Sun Dec 26, 2010 4:56 pm
by walleye
This is a more interesting variation in my opinion.
$$Wc This is a label for the diagram. $$ ------------------------------- $$ | 1 . O 3 . X . . . . . . . . $$ | X O O X X X O O O O . . . . $$ | 2 X . X O O X X X X O O . . $$ | O X X X O O O X . X O . O . $$ | . O O O . O X . X O O O . . $$ | . O . . O O X X X O . . . . $$ | . O O O . O O . . . . . . . $$ | . X X O X X O . . . . . . . $$ | . X O X . . X X . . . . . . $$ | . . . X X X . . . , . . . . $$ | . . . X . . . . . . . . . . $$ | . . . . . . . . . . . . . .
[go]$$Wc This is a label for the diagram. $$ ------------------------------- $$ | 1 . O 3 . X . . . . . . . . $$ | X O O X X X O O O O . . . . $$ | 2 X . X O O X X X X O O . . $$ | O X X X O O O X . X O . O . $$ | . O O O . O X . X O O O . . $$ | . O . . O O X X X O . . . . $$ | . O O O . O O . . . . . . . $$ | . X X O X X O . . . . . . . $$ | . X O X . . X X . . . . . . $$ | . . . X X X . . . , . . . . $$ | . . . X . . . . . . . . . . $$ | . . . . . . . . . . . . . .[/go]
Re: Tsumego from a game
Posted: Sun Dec 26, 2010 11:39 pm
by ethanb
walleye wrote:
This is a more interesting variation in my opinion.
$$Wc This is a label for the diagram. $$ ------------------------------- $$ | 1 . O 3 . X . . . . . . . . $$ | X O O X X X O O O O . . . . $$ | 2 X . X O O X X X X O O . . $$ | O X X X O O O X . X O . O . $$ | . O O O . O X . X O O O . . $$ | . O . . O O X X X O . . . . $$ | . O O O . O O . . . . . . . $$ | . X X O X X O . . . . . . . $$ | . X O X . . X X . . . . . . $$ | . . . X X X . . . , . . . . $$ | . . . X . . . . . . . . . . $$ | . . . . . . . . . . . . . .
[go]$$Wc This is a label for the diagram. $$ ------------------------------- $$ | 1 . O 3 . X . . . . . . . . $$ | X O O X X X O O O O . . . . $$ | 2 X . X O O X X X X O O . . $$ | O X X X O O O X . X O . O . $$ | . O O O . O X . X O O O . . $$ | . O . . O O X X X O . . . . $$ | . O O O . O O . . . . . . . $$ | . X X O X X O . . . . . . . $$ | . X O X . . X X . . . . . . $$ | . . . X X X . . . , . . . . $$ | . . . X . . . . . . . . . . $$ | . . . . . . . . . . . . . .[/go]
If the seki isn't enough for white to win, maybe he can hope that black makes a mistake and starts a ko. But white loses about 1.5 points (on the outside) by making this seki instead of the other one. Amusing stuff happens if black captures six stones inside though (it's still a ko.)
Re: Tsumego from a game
Posted: Mon Dec 27, 2010 12:48 am
by walleye
ethanb wrote:
Amusing stuff happens if black captures six stones inside though (it's still a ko.)
What ko? If white doesn't make a seki, Black can live by capturing. There is no ko there as far as I can see.
Re: Tsumego from a game
Posted: Mon Dec 27, 2010 1:07 am
by ethanb
walleye wrote:
ethanb wrote:
Amusing stuff happens if black captures six stones inside though (it's still a ko.)
What ko? If white doesn't make a seki, Black can live by capturing. There is no ko there as far as I can see.
Ack, you're right - it's past my bedtime. I forgot about number 5 in the next diagram when I was reading ahead.
$$Bc Yet another diagram label. $$ ------------------------------- $$ | O 2 O O 3 X 4 . . . . . . . $$ | X O O X X X O O O O . . . . $$ | X X 5 X O O X X X X O O . . $$ | O X X X O O O X . X O . O . $$ | 1 O O O . O X . X O O O . . $$ | . O . . O O X X X O . . . . $$ | . O O O . O O . . . . . . . $$ | . X X O X X O . . . . . . . $$ | . X O X . . X X . . . . . . $$ | . . . X X X . . . , . . . . $$ | . . . X . . . . . . . . . . $$ | . . . . . . . . . . . . . .
[go]$$Bc Yet another diagram label. $$ ------------------------------- $$ | O 2 O O 3 X 4 . . . . . . . $$ | X O O X X X O O O O . . . . $$ | X X 5 X O O X X X X O O . . $$ | O X X X O O O X . X O . O . $$ | 1 O O O . O X . X O O O . . $$ | . O . . O O X X X O . . . . $$ | . O O O . O O . . . . . . . $$ | . X X O X X O . . . . . . . $$ | . X O X . . X X . . . . . . $$ | . . . X X X . . . , . . . . $$ | . . . X . . . . . . . . . . $$ | . . . . . . . . . . . . . .[/go]
$$Bc White fails to make a ko. $$ ------------------------------- $$ | . 6 7 . X X O . . . . . . . $$ | X . W X X X O O O O . . . . $$ | X X X X O O X X X X O O . . $$ | . X X X O O O X . X O . O . $$ | X O O O . O X . X O O O . . $$ | . O . . O O X X X O . . . . $$ | . O O O . O O . . . . . . . $$ | . X X O X X O . . . . . . . $$ | . X O X . . X X . . . . . . $$ | . . . X X X . . . , . . . . $$ | . . . X . . . . . . . . . . $$ | . . . . . . . . . . . . . .
[go]$$Bc White fails to make a ko. $$ ------------------------------- $$ | . 6 7 . X X O . . . . . . . $$ | X . W X X X O O O O . . . . $$ | X X X X O O X X X X O O . . $$ | . X X X O O O X . X O . O . $$ | X O O O . O X . X O O O . . $$ | . O . . O O X X X O . . . . $$ | . O O O . O O . . . . . . . $$ | . X X O X X O . . . . . . . $$ | . X O X . . X X . . . . . . $$ | . . . X X X . . . , . . . . $$ | . . . X . . . . . . . . . . $$ | . . . . . . . . . . . . . .[/go]
So yeah, just a seki, but 1.5 points worse than the other one.
Actually, even if the spot below the marked stone was miraculously open, black could just connect to the right of 7 and it would still be seki.
Re: Tsumego from a game
Posted: Tue Dec 28, 2010 7:58 am
by Bill Spight
There is one point that has not been mentioned.
(;ST[2]FF[4]AP[GOWrite:2.2.21]CA[ISO8859-1]GM[1]SZ[19]C[As a tsumego status problem, Black is alive. ]PL[b]AB[dc][ge][ba][fa][bc][ie][dk][gi][hi][gc][bi][hc][ic][di][jc][cd][fh][bd][ab][dd][gf][hf][if][hd][jd][fj][fb][ch][bh][dj][db][eh][ej][eb]DT[2010-12-28]PW[ ]AW[fg][cg][fc][ca][dg][ec][fe][ke][le][gg][je][ce][de][be][kc][lc][ci][gh][bb][ef][cb][ff][ed][gd][fd][jf][bf][jb][kd][hb][md][ib][gb][dh][bg][ad]PB[ ]PM[0]FG[259:] ( ;C[*** Black to play can make two eyes.]B[da] ) ( ;C[*** White to play can take an eye.]W[da] ;B[ac] ( ;C[*** After White responds. . .]W[ae] ( ;C[*** Black can make at least seki.]B[aa] ( ;C[*** Seki.]W[ga] ) ( ;C[*** Black captures.]B[cc] ;W[ga] ;B[ea] )
) ( ;C[*** Under some circumstances, Black can allow this 10,000 year ko.]W[ga] )
( ;C[*** Under some circumstances, Black can play this ko.]B[cc] )
) ( ;C[*** Taking the ko is a mistake.]W[aa] ;B[ae] ;W[ga] ;B[cc] ;C[*** White is dead in a double ko.]W[af] )
)
( ;C[*** A mistake.]W[aa] ;B[ac] ( ;W[da] ;B[ae] ;W[ga] ;B[cc] ;C[*** White is dead in double ko.]W[af] ) ( ;W[ae] ;C[*** Black has two eyes.]B[da] )
)
)
Re: Tsumego from a game
Posted: Tue Dec 28, 2010 8:50 am
by Magicwand
if double ko then black is alive but this does not necessary guarantee win. if white can create a double ko somewhere else then black can make no decision. having infinite ko is pretty strong advantage that can create havoc somewhere else. so answer is not so clear cut.
all depends on the situation is the correct answer.
