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| Exciting problem to decide a game http://www.lifein19x19.com/viewtopic.php?f=15&t=5099 |
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| Author: | Uberdude [ Mon Dec 05, 2011 3:02 pm ] |
| Post subject: | Exciting problem to decide a game |
The position below is adapted from a recent game of mine. White has just passed, so it is black's move. White could have played j15 as the dame were being filled to fix the bad aji of the 2 black stones inside white's area, but then he would have lost by 0.5 points (Japanese rules). But bad aji won't win the game for black, he must find a sequence that works against any white resistance. The stakes could not be higher! Note that a ko can be assumed as a success for black, as he only needs to gain 1 point to win the game, and there were indeed threats on the rest of the board. I have studied this position extensively and I believe black can win, though it is possible I missed something. This is a hard problem, to solve it without playing it out I think you need to be a high dan. I will give a few hints below, and post my solution later. Hints: |
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| Author: | Magicwand [ Mon Dec 05, 2011 5:49 pm ] |
| Post subject: | Re: Exciting problem to decide a game |
i looked at it for 3 min and can not find any... i will try later when i have more time. |
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| Author: | Magicwand [ Mon Dec 05, 2011 6:12 pm ] |
| Post subject: | Re: Exciting problem to decide a game |
are you sure that there is answer to this question??? i spent few more minute..and i dont see anything but aji. |
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| Author: | Loons [ Mon Dec 05, 2011 7:41 pm ] |
| Post subject: | Re: Exciting problem to decide a game |
I just see dead ends as well. Albeit, I will now look at the hints. Quite boring: ...Guess I was nowhere close |
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| Author: | cyclops [ Mon Dec 05, 2011 7:57 pm ] |
| Post subject: | Re: Exciting problem to decide a game |
Without using the hint after a few minutes this 7kyu came up with: edit: In the next post MagicWand exposes my mistake quite clearly. So skip my post please. |
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| Author: | Magicwand [ Mon Dec 05, 2011 8:03 pm ] |
| Post subject: | Re: Exciting problem to decide a game |
cyclops wrote: Without using the hint after a few minutes this 7kyu came up with: |
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| Author: | Joaz Banbeck [ Tue Dec 06, 2011 12:40 am ] |
| Post subject: | Re: Exciting problem to decide a game |
| Author: | Uberdude [ Tue Dec 06, 2011 11:27 am ] |
| Post subject: | Re: Exciting problem to decide a game |
Loons wrote: I just see dead ends as well. Albeit, I will now look at the hints. ...Guess I was nowhere close You were on the right track, but seemed to give up before it was clear what happened. Keep going, the main lines are 20-25 moves long. |
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| Author: | cyclops [ Tue Dec 06, 2011 5:00 pm ] |
| Post subject: | Re: Exciting problem to decide a game |
Uberdude wrote: You were on the right track, but seemed to give up before it was clear what happened. Keep going, the main lines are 20-25 moves long. So I continued from Loons last diagram: edit: so loons, in his latter diagram, better moves  to H14 
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| Author: | ez4u [ Tue Dec 06, 2011 7:06 pm ] |
| Post subject: | Re: Exciting problem to decide a game |
I think loons was closest with this diagram. But not yet spot on. |
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| Author: | yeah [ Wed Dec 07, 2011 12:09 am ] |
| Post subject: | Re: Exciting problem to decide a game |
ez4u wrote: I think loons was closest with this diagram. But not yet spot on. And why not 4 at h14? |
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| Author: | ez4u [ Wed Dec 07, 2011 1:12 am ] |
| Post subject: | Re: Exciting problem to decide a game |
yeah wrote: ez4u wrote: I think loons was closest with this diagram. But not yet spot on. And why not 4 at h14? |
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| Author: | yeah [ Wed Dec 07, 2011 1:29 am ] |
| Post subject: | Re: Exciting problem to decide a game |
ez4u wrote: yeah wrote: ez4u wrote: I think loons was closest with this diagram. But not yet spot on. And why not 4 at h14? Something is weird with that diagram. Stones missing. |
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| Author: | ez4u [ Wed Dec 07, 2011 4:07 am ] |
| Post subject: | Re: Exciting problem to decide a game |
yeah wrote: Something is weird with that diagram. Stones missing. |
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| Author: | yeah [ Wed Dec 07, 2011 4:27 am ] |
| Post subject: | Re: Exciting problem to decide a game |
Hups I got confused. |
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| Author: | cyclops [ Wed Dec 07, 2011 6:08 am ] |
| Post subject: | Re: Exciting problem to decide a game |
I like Dave's solution a lot. Elegant and straightforward. Especially his  is brilliant. To be sure I tried different 's. at H14 or at H16 both fail smoothly. Statistically I am wrong and I apologize for disturbing this discussion of dans but it seems my previous post shows an alternative for Dave's  at H15. Would anyone point out my mistake(s)?edited after ezru reply: indeed it is more complex and indeed possibly wrong |
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| Author: | ez4u [ Wed Dec 07, 2011 6:18 am ] |
| Post subject: | Re: Exciting problem to decide a game |
cyclops wrote: I like Dave's solution a lot. Elegant and straightforward. Especially his is brilliant. To be sure I tried different 's. at H14 or at H16 both fail smoothly. Statistically I am wrong and I apologize for disturbing this discussion of dans but it seems my previous post shows an alternative for Dave's at H15. Would anyone point out my mistake(s)?It wasn't clear to me that Black has a clean finish if White answers simply H14. I could be wrong though. It just seemed more complex. |
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| Author: | Uberdude [ Wed Dec 07, 2011 6:01 pm ] |
| Post subject: | Re: Exciting problem to decide a game |
I had missed the of Dave's solution, and it does indeed seem to work rather cleanly. But there is this white almost-resistance (although 6 is ugly it does prolong death the most):(If 4 connects at 5 then black plays 4 for a snapback) My solution was as the h15 net: it does work too though with rather more and longer variations. If white answers the h15 net with h14 black can still win, and I would encourage you to keep exploring that way as there is a rather exqusite double snapback as your prize at the end of one line  A few comments on cyclop's sgf, which shared a few sequences with my solution but had a few mistakes/gaps: At this position cyclops cut at b, but a kills in a one-way-street as below (  at  succumbs to the throw in at 3).You showed this sequence: After  and black a then white b, but white need not save the stone at b and can simply connect at c: then all white's groups are safe and black capturing one stone is only 1 eye so dead inside. So rewinding a few moves, black should play  as below for a lovely connect-and-die (11 at a):Given that the above succeeds for black, white can try as below (note that Dave's solution prevents white doing this as the exchange of 9 for 10 in the first diagram (3 for 6 here) is after white plays 8 here): White lives on top (if white doesn't play  black plays there), but black cut in sente so makes a seki. This is why I said the dango not eye in the lower left was relevant. Dave's solution is better in that it doesn't need this.So that's pretty much covered the variations following white 4 at a, so how about the sub-problem of black to play below. Despite what seems like the sub-optimal he can still win. |
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| Author: | cyclops [ Fri Dec 09, 2011 4:41 am ] |
| Post subject: | Re: Exciting problem to decide a game |
public answer to previous post, hidden to save space |
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| Author: | cyclops [ Fri Dec 09, 2011 5:40 pm ] |
| Post subject: | Re: Exciting problem to decide a game |
6 and 8 are forced. Next, because he wins any ko, black 9 captures the top right. No double snapback needed. |
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