In your second diagram, Black should play
at 
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| Tsumego answer http://www.lifein19x19.com/viewtopic.php?f=11&t=17407 |
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| Author: | libcat [ Sun Apr 19, 2020 1:45 pm ] |
| Post subject: | Tsumego answer |
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) |
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| Author: | jlt [ Sun Apr 19, 2020 2:00 pm ] |
| Post subject: | Re: Tsumego answer |
In your second diagram, Black should play at
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| Author: | xela [ Sun Apr 19, 2020 4:13 pm ] |
| Post subject: | Re: Tsumego answer |
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? 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. Details: what jlt said :-) libcat wrote: Also, can someone tell me if this is supposed to be a common life and death shape? 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). |
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| Author: | Uberdude [ Mon Apr 20, 2020 6:00 am ] |
| Post subject: | Re: Tsumego answer |
Picture worth 100 words: |
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| Author: | Bill Spight [ Mon Apr 20, 2020 8:00 am ] |
| Post subject: | Re: Tsumego answer |
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. Worth repeating. 
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| Author: | Bill Spight [ Mon Apr 20, 2020 8:22 am ] |
| Post subject: | Re: Tsumego answer |
Just to add my 2ยข. libcat 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? You are right that if  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. libcat wrote: I thought it might turn out like this but not sure how probable this is: (Diagram edited by me.) 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.
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| Author: | libcat [ Mon Apr 20, 2020 9:08 am ] |
| Post subject: | 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'. |
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| Author: | libcat [ Mon Apr 20, 2020 9:39 am ] |
| Post subject: | Re: Tsumego answer |
Bill Spight wrote: 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. Thanks for the explanation, it's helped to convince me that I was a bit daft to put Black at :/ 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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| Author: | xela [ Mon Apr 20, 2020 4:22 pm ] |
| Post subject: | Re: Tsumego answer |
libcat wrote: Woah, this forum is great! Totally agree. Keep on posting interesting questions for us :-) |
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