Can someone please help me to understand this solution?
I guessing it should mean that the five white stones in surrounded by black are dead. But couldn't white still play Q19?
I thought it might turn out like this but not sure how probable this is:
Also, can someone tell me if this is supposed to be a common life and death shape?
Source
(Sorry I can't seem to get the coordinates to display on the right side of the board)
Tsumego answer
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xela
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Re: Tsumego answer
Big picture: the focus isn't on capturing a few white stones, it's on whether the black group can live. Capturing stones is just a means to an end.libcat wrote:I guessing it should mean that the five white stones in surrounded by black are dead. But couldn't white still play Q19?
Details: what jlt said :-)
Not a common L&D shape as such. But the throw-in (sacrificing a black stone at R17) is a common technique, so stronger players would see the key move at a glance (and then maybe spend a few seconds reading to check that it works in this context).libcat wrote:Also, can someone tell me if this is supposed to be a common life and death shape?
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Uberdude
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Bill Spight
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Re: Tsumego answer
Worth repeating.xela wrote:Big picture: the focus isn't on capturing a few white stones, it's on whether the black group can live. Capturing stones is just a means to an end.
The Adkins Principle:
At some point, doesn't thinking have to go on?
— Winona Adkins
Visualize whirled peas.
Everything with love. Stay safe.
At some point, doesn't thinking have to go on?
— Winona Adkins
Visualize whirled peas.
Everything with love. Stay safe.
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Bill Spight
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Re: Tsumego answer
Just to add my 2¢.
connects at 1, Black could capture the resulting clump of 6 White stones. They would be more than dead. 
You are also right that should capture the single Black stone by playing at Q-19.
If Black fills at
, it is possible that White will save his 
stones by filling at 
. should capture the stones by playing at 6. In fact, capturing the White stones was the point of the original throw-in.
BTW, life and death problems often occur in restricted spaces, because with enough space it is usually easy to live. Typically, but not always, they will involve a potential 1 pt. eye, because that's the smallest eye you can make, and space is at a premium. In this problem, where is Black's potential one point eye? At 5. It is typically important for Black not to fill that eye. (!)
In fact, after fills the potential one point eye, the Black group is dead as it lies, given alternating local play. Even if Black captures the three White stones that are in atari, White can kill, as you may verify.
You are right that iflibcat wrote:Can someone please help me to understand this solution?
I guessing it should mean that the five white stones in surrounded by black are dead. But couldn't white still play Q19?
connects at 1, Black could capture the resulting clump of 6 White stones. They would be more than dead. You are also right that should capture the single Black stone by playing at Q-19. (Diagram edited by me.)libcat wrote:I thought it might turn out like this but not sure how probable this is:
If Black fills at
, it is possible that White will save his stones by filling at . should capture the stones by playing at 6. In fact, capturing the White stones was the point of the original throw-in. BTW, life and death problems often occur in restricted spaces, because with enough space it is usually easy to live.
Typically, but not always, they will involve a potential 1 pt. eye, because that's the smallest eye you can make, and space is at a premium. In this problem, where is Black's potential one point eye? At 5. It is typically important for Black not to fill that eye. (!)In fact, after
fills the potential one point eye, the Black group is dead as it lies, given alternating local play. Even if Black captures the three White stones that are in atari, White can kill, as you may verify. The Adkins Principle:
At some point, doesn't thinking have to go on?
— Winona Adkins
Visualize whirled peas.
Everything with love. Stay safe.
At some point, doesn't thinking have to go on?
— Winona Adkins
Visualize whirled peas.
Everything with love. Stay safe.
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libcat
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Re: Tsumego answer
Woah, this forum is great! 
@JLT / Xela / Uberdude
Thanks - I was staring at the screen for ages and still couldn't see it.
Okay I'm going check out 'throw-ins'.
@JLT / Xela / Uberdude
Thanks - I was staring at the screen for ages and still couldn't see it.
Okay I'm going check out 'throw-ins'.
Last edited by libcat on Mon Apr 20, 2020 9:40 am, edited 2 times in total.
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libcat
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Re: Tsumego answer
Thanks for the explanation, it's helped to convince me that I was a bit daft to put Black atBill Spight wrote: BTW, life and death problems often occur in restricted spaces, because with enough space it is usually easy to live.
In fact, after
:/ In fact, for most of the time when trying to solve this, I actually completely forgot about the 1 pt eye that you mentioned!
I look forward to getting more smiley-filled help posts from you in the future
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xela
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Re: Tsumego answer
Totally agree. Keep on posting interesting questions for us :-)libcat wrote:Woah, this forum is great!