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| Why is this solution wrong? http://lifein19x19.com/viewtopic.php?f=11&t=16742 |
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| Author: | Jika [ Thu Jul 04, 2019 10:48 pm ] |
| Post subject: | Why is this solution wrong? |
Attachment: Bildschirmfoto vom 2019-07-05 07-44-36.png [ 1.53 KiB | Viewed 9677 times ] Hi, I see why 6-6 is good. Why is 1-5 wrong? I've tried playing it out, and to me it seems the white group on the left can be captured, leaving black with a lot of territory. So, I must be overlooking something white can do. What? |
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| Author: | Fenring [ Thu Jul 04, 2019 11:02 pm ] |
| Post subject: | Re: Why is this solution wrong? |
white can capture the 4 black stones on the bottom |
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| Author: | Bill Spight [ Fri Jul 05, 2019 12:25 am ] |
| Post subject: | Re: Why is this solution wrong? |
Jika wrote: Attachment: Bildschirmfoto vom 2019-07-05 07-44-36.png Hi, I see why 6-6 is good. Why is 1-5 wrong? I've tried playing it out, and to me it seems the white group on the left can be captured, leaving black with a lot of territory. So, I must be overlooking something white can do. What? It helps to count the dame of each group. That tells you the minimum number of plays to take the stones. In this case the White stones on the left have 5 dame, the Black stones on the bottom have 3 dame. No contest. 
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| Author: | zermelo [ Fri Jul 05, 2019 5:50 am ] |
| Post subject: | Re: Why is this solution wrong? |
So, to make it more explicit, if black plays 1-5, white will just play a move that saves the cutting stones, e.g. either of the 5-6 points. Now, as Bill said, the bottom 4 black stones cannot be saved anymore. By the way, I'm not sure which 1-5 you mean. If you mean one on the bottom row, maybe you think it threatens capturing the two white stones. But it does not. |
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| Author: | Uberdude [ Fri Jul 05, 2019 7:23 am ] |
| Post subject: | Re: Why is this solution wrong? |
Use http://hiddema.nl/diagrammer/ to make go diagrams, takes < 1 minute: Jika, is this  you meant? |
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| Author: | Jika [ Fri Jul 05, 2019 11:44 am ] |
| Post subject: | Re: Why is this solution wrong? |
(Just trying out the diagrammer) Yes, that was the point I meant. I did not realize that white has no need to defend the group on the left and can attack instead. Sorry for the stupid question!! I think this is the problem when I try to play something out, I tried the "best" moves fot the defense of the left white group, but did not see at all the rest. |
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| Author: | Bill Spight [ Fri Jul 05, 2019 1:09 pm ] |
| Post subject: | Re: Why is this solution wrong? |
Jika wrote: (Just trying out the diagrammer) Yes, that was the point I meant. I did not realize that white has no need to defend the group on the left and can attack instead. Sorry for the stupid question!! I think this is the problem when I try to play something out, I tried the "best" moves fot the defense of the left white group, but did not see at all the rest. (Emphasis mine.) This is not a stupid question. In fact, it is a very intelligent question, since it is based upon your attempt to understand this position, and not simply solve the problem. Keep that up and you will gain understanding rapidly. As is often said, and not just about go, the best defense is often a good offense. You have learned an important lesson. But I think that there are a couple of other questions lurking here. One has to do with taking the opponent's view when reading. You realized that this is important, that you missed something for White. Perhaps this was because you adopted the perspective that Black is attacking and White is defending. That is, that White is merely responding to Black's play. If you look at this situation from the perspective that White has his own goals, including attacking Black's stones, then you can see that White can capture Black before Black can capture White. A related point is that when reading your should try to disprove your ideas. is played with the idea of capturing the White stones in the very corner. If that is true, Black should succeed against every reply by White. Since you are a rank beginner, that almost means a brute force search, as far as White's plays are concerned. OC, White may be able to live, so you want to consider the a moves. But even if White plays both of them, Black can play at  and hold White to one eye. So you need to consider the b moves, and maybe others. OC, the b moves threaten the Black stones.
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| Author: | EdLee [ Fri Jul 05, 2019 6:04 pm ] |
| Post subject: | Re: Why is this solution wrong? |
Hi Jika, Since there are two 1-5 points locally, it's more clear if you use a diagram ( which you're picking up ): Or a letter: Or coordinates: To repeat Bill's point: |
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| Author: | Bill Spight [ Fri Jul 05, 2019 7:50 pm ] |
| Post subject: | Re: Why is this solution wrong? |
Thanks, Ed. It is important to note that, in addition to the two dame, , the  stones have a third liberty,  , because Black has to play there to take them. That's why the dame count only indicates the minimum number of plays to take stones, sometimes it takes one or more extra moves. cannot escape, because  blocks. It also holds White to two dame. (I'm sure you saw that. )I suppose this solution diagram was not shown.  Otherwise you would have seen the vulnerability of the  stones. Also, the problem statement should have been, Black to play and save the stones.There is something to be said for not showing solution diagrams and for not indicating the goal of the problem. But that's for experienced players, not beginners. Edit: Note: In a real game White might not play -  right away, or Black might later play at 2 instead, but that is a different question.
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| Author: | Jika [ Fri Jul 05, 2019 11:11 pm ] |
| Post subject: | Re: Why is this solution wrong? |
Thanks to you all. Yes, Bill, 321go does not provide solutions for the problems. Often it allows for a few other paths, like "And now...?" (and one may play on for one or two moves before it says "wrong"). Since quite often (but getting fewer! ) I can't see why this is wrong or correct, I try playing it out (using the qGo SGF editor, so I think by saving my moves I could even upload them here?).Yes, considering more moves of the opponent should be better. As AmyBot-beginner on OGS was full (20 players), I changed to BasicBot KGS, which is actually IdiotBot. Someone here posted IdiotBot makes "random" moves, but not always: I found it quite interesting to notice that often it won't defend or attack where I saw just too late what would happen. Like the bot is saying, hey, I'm giving you a new chance, do you see it now? It was entertaining and motivating to have the time and opportunity to correct mistakes. I think this trains to see the perspective of both parties. And I dared attacking a bit instead of just running after the bots moves anxiously. (Only problem with beginner bots seems to be that some count Chinese, others Japanese, and I had some very disappointing results when I played the wrong style  )Ed, thank you for the diagrams. Yes, I will try to post diagrams in future to clarify my question. |
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| Author: | Mike Novack [ Sat Jul 06, 2019 8:16 am ] |
| Post subject: | Re: Why is this solution wrong? |
Also going to point something out. Black is capturing those white stones stones in sente. Look at Bill's diagram again to see that the white corner stones are saved BUT white had to use a move to save them. Means it is still black's move. In effect black captured those stones without using a move. One of the thing really hard for beginners to grasp is the difference between sets and gote and the value of sente. That is why people are saying that white probably would not use a move NOW to respond to 6-6 but would wait till there was a ko. White can't now save that group of stones and could save the corner stones only in gote but the situation offers a number of ko threats. |
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| Author: | Jika [ Sat Jul 06, 2019 11:54 am ] |
| Post subject: | Re: Why is this solution wrong? |
Quote: Black is capturing those white stones stones in sente. Look at Bill's diagram again to see that the white corner stones are saved BUT white had to use a move to save them. Means it is still black's move. In effect black captured those stones without using a move. Thanks, Mike. Could you explain which diagram you are referring to? I don't get what stones are saved, what are captured so that it is still black's move. I'm not sure I will ever be able to do that (keep a local situation in mind and come back to it at a time when it seems better)... |
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| Author: | Mike Novack [ Sat Jul 06, 2019 4:33 pm ] |
| Post subject: | Re: Why is this solution wrong? |
The last of Bill's After black captures with 5, if white does not use 6 to connect the corner stones out, black can kill them. |
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| Author: | Comte [ Wed Feb 19, 2020 9:44 am ] |
| Post subject: | Re: Why is this solution wrong? |
This is just a general comment about 321Go. It is a very good site with thousands of problems. But I have found a handful of problems for which I think the answers were wrong. |
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