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GoChild Problem
http://www.lifein19x19.com/viewtopic.php?f=11&t=3296
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Author:  ninestone [ Thu Feb 24, 2011 1:36 pm ]
Post subject:  GoChild Problem

I'm going through the problems on GoChild, and it marks my answer as wrong but I can't see why. The problem is #98 of the Basic 900 Connect and Cut pack:
Click Here To Show Diagram Code
[go]$$c
$$ ----------------------------
$$ | . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . |
$$ | . . . , . . , . . , . . . |
$$ | . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . |
$$ | . . . , . . , . . , . . . |
$$ | . . O O . . . . . . . . . |
$$ | . O . . O . . . . . . . . |
$$ | . . O O . O O O O O O . . |
$$ | X X X X O X X X X X O . . |
$$ | . . X O . O X . . X O . . |
$$ | . . X . . . . . . X . . . |
$$ ---------------------------[/go]

My answer was :b1: at F1, and a :w2: response at E1 shows as wrong. But capturing with :b3: at E2 strikes me as a perfectly valid solution. What am I not seeing?

Author:  Magicwand [ Thu Feb 24, 2011 1:40 pm ]
Post subject:  Re: GoChild Problem

Click Here To Show Diagram Code
[go]$$c
$$ ----------------------------
$$ | . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . |
$$ | . . . , . . , . . , . . . |
$$ | . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . |
$$ | . . . , . . , . . , . . . |
$$ | . . O O . . . . . . . . . |
$$ | . O . . O . . . . . . . . |
$$ | . . O O . O O O O O O . . |
$$ | X X X X O X X X X X O . . |
$$ | . . X O 3 O X . . X O . . |
$$ | . . X 4 1 2 . . . X . . . |
$$ ---------------------------[/go]


Click Here To Show Diagram Code
[go]$$c
$$ ----------------------------
$$ | . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . |
$$ | . . . , . . , . . , . . . |
$$ | . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . |
$$ | . . . , . . , . . , . . . |
$$ | . . O O . . . . . . . . . |
$$ | . O . . O . . . . . . . . |
$$ | . . O O . O O O O O O . . |
$$ | X X X X O X X X X X O . . |
$$ | . . X O 5 O X . . X O . . |
$$ | . . X O 6 O 7 . . X . . . |
$$ ---------------------------[/go]

Author:  daal [ Thu Feb 24, 2011 1:45 pm ]
Post subject:  Re: GoChild Problem

E2 makes a ko. This gives white a chance to keep you separated and kill at least one of your groups. There is a better answer. :)

Edit: which you can see above, if Magicwand doesn't hide it...

Author:  quantumf [ Thu Feb 24, 2011 1:46 pm ]
Post subject:  Re: GoChild Problem

ninestone wrote:
I'm going through the problems on GoChild, and it marks my answer as wrong but I can't see why. The problem is #98 of the Basic 900 Connect and Cut pack:
Click Here To Show Diagram Code
[go]$$c
$$ ----------------------------
$$ | . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . |
$$ | . . . , . . , . . , . . . |
$$ | . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . |
$$ | . . . , . . , . . , . . . |
$$ | . . O O . . . . . . . . . |
$$ | . O . . O . . . . . . . . |
$$ | . . O O . O O O O O O . . |
$$ | X X X X O X X X X X O . . |
$$ | . . X O . O X . . X O . . |
$$ | . . X . . . . . . X . . . |
$$ ---------------------------[/go]

My answer was :b1: at F1, and a :w2: response at E1 shows as wrong. But capturing with :b3: at E2 strikes me as a perfectly valid solution. What am I not seeing?


Click Here To Show Diagram Code
[go]$$c
$$ ----------------------------
$$ | . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . |
$$ | . . . , . . , . . , . . . |
$$ | . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . |
$$ | . . . , . . , . . , . . . |
$$ | . . O O . . . . . . . . . |
$$ | . O . . O . . . . . . . . |
$$ | . . O O . O O O O O O . . |
$$ | X X X X O X X X X X O . . |
$$ | . . X O 3 . X . . X O . . |
$$ | . . X . 2 1 . . . X . . . |
$$ ---------------------------[/go]


ko

Author:  ninestone [ Thu Feb 24, 2011 2:01 pm ]
Post subject:  Re: GoChild Problem

I saw that it's ko. There are no threats for white so the only response is to connect at E4. Maybe I just have an aversion to calling the solution wrong just because it's not exactly what the author wanted. And capturing 5 stones is optimistic when white can connect after the peep (that's another solution GoChild accepts).

Author:  Chew Terr [ Thu Feb 24, 2011 2:09 pm ]
Post subject:  Re: GoChild Problem

9stone:
Click Here To Show Diagram Code
[go]$$c
$$ ----------------------------
$$ | . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . |
$$ | . . . , . . , . . , . . . |
$$ | . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . |
$$ | . . . , . . , . . , . . . |
$$ | . . O O . . . . . . . . . |
$$ | . O . . O . . . . . . . . |
$$ | . . O O 4 O O O O O O . . |
$$ | X X X X O X X X X X O . . |
$$ | . . X O 2 O X . . X O . . |
$$ | . . X 5 1 3 . . . X . . . |
$$ ---------------------------[/go]


With ko in go problems, you have to assume that there MAY be threats elsewhere. For that reason, ko is worse than life. And for this connection problem, if you can connect without ko, it's superior to ko. So gochild is hoping for something like this, as 'ideal for both sides'. If W could separate black, W could kill at least one side by making it a dead shape. However, by connecting, black saves both. White can't play 4 @ 5 because then she would be in atari.

Author:  daal [ Thu Feb 24, 2011 2:14 pm ]
Post subject:  Re: GoChild Problem

ninestone wrote:
I saw that it's ko. There are no threats for white so the only response is to connect at E4. Maybe I just have an aversion to calling the solution wrong just because it's not exactly what the author wanted. And capturing 5 stones is optimistic when white can connect after the peep (that's another solution GoChild accepts).



Click Here To Show Diagram Code
[go]$$c white can't play a
$$ ----------------------------
$$ | . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . |
$$ | . . . , . . , . . , . . . |
$$ | . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . |
$$ | . . . , . . , . . , . . . |
$$ | . . O O . . . . . . . . . |
$$ | . O . . O . . . . . . . . |
$$ | . . O O . O O O O O O . . |
$$ | X X X X O X X X X X O . . |
$$ | . . X O 2 O X . . X O . . |
$$ | . . X a 1 3 . . . X . . . |
$$ ---------------------------[/go]


It's not that black can necessarily capture stones, but if w connects after the peep. black connects and is unconditionally alive. Usually when doing this type of problem, we assume that there are ko threats elsewhere, even if they are not shown on the diagram, and if it's possible to survive without ko, then that's better.

Author:  ninestone [ Thu Feb 24, 2011 2:18 pm ]
Post subject:  Re: GoChild Problem

These connect and cut problems make me feel like I'm too stupid to play Go. I nailed everything up to them, and now I don't get any.

Author:  Chew Terr [ Thu Feb 24, 2011 2:22 pm ]
Post subject:  Re: GoChild Problem

ninestone wrote:
These connect and cut problems make me feel like I'm too stupid to play Go. I nailed everything up to them, and now I don't get any.


Oh, don't worry, they're really tough. If you have a bad time with them, you can always work on a different set and come back later. That set and some of the endgame sets are particularly merciless.

Author:  ninestone [ Thu Feb 24, 2011 2:25 pm ]
Post subject:  Re: GoChild Problem

That's good to know.

Author:  judicata [ Thu Feb 24, 2011 2:44 pm ]
Post subject:  Re: GoChild Problem

ninestone wrote:
These connect and cut problems make me feel like I'm too stupid to play Go. I nailed everything up to them, and now I don't get any.


Starting out, I found "connect and capture" and shortage of liberties problems to be difficult to grasp at first--keep practicing and you'll get the hang of it.

Author:  Shaddy [ Thu Feb 24, 2011 10:07 pm ]
Post subject:  Re: GoChild Problem

I looked at the connect and cut series and got a few of them wrong on the first try, and then I recognised a problem from what I think was a dan-level problem book. So don't get discouraged, heh..

Author:  Bill Spight [ Fri Feb 25, 2011 1:47 am ]
Post subject:  Re: GoChild Problem

ninestone wrote:
I saw that it's ko. There are no threats for white so the only response is to connect at E4.


Not so, as I shall show below. :)

Quote:
Maybe I just have an aversion to calling the solution wrong just because it's not exactly what the author wanted.


Oh, go players are quite aware that a problem may have multiple solutions. That is not the case here. There is only one solution.

Quote:
And capturing 5 stones is optimistic when white can connect after the peep (that's another solution GoChild accepts).


It's not another solution, it's another variation. For Black to have a solution, it has to work for every reply White could make. In fact, capturing the 5 stones is the key variation because Black has to see the tesuji combination of throwing away three stones to reduce White's liberties. GoChild should not really accept a solution that does not include that variation. (IMO, it should not accept a solution without both variations.) In real life, White should not choose that variation, but this is a problem for Black, not White. :)

WHy is ko not a solution? First, because it is unsure. If there is a sure way to kill or live or connect or cut, ko is not the solution. (Sometimes double ko is the solution, if it provides a sure way.) One reason for that is that you may lose the ko in real life. The problem does not show the whole board, so we do not know the ko threat situation. (Oh, looking at the diagram, perhaps GoChild shows the whole board. It should not. If this were the whole board, Black could resign. ;)) Let me illustrate the other reason below.

Click Here To Show Diagram Code
[go]$$Bc Real life variation
$$ ----------------------------
$$ | . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . |
$$ | . . . , . . , . . , . . . |
$$ | . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . |
$$ | . . . , . . , . . , . . . |
$$ | . . O O . . . . . . . . . |
$$ | . O . . O . . . . . . . . |
$$ | . . O O 4 O O O O O O . . |
$$ | X X X X O X X X X X O . . |
$$ | . . X O 2 O X . . X O . . |
$$ | . . X 5 1 3 . . . X . . . |
$$ ---------------------------[/go]


:b1: connects. White can save :w2: and :w4: as ko threats.

Click Here To Show Diagram Code
[go]$$Bc Ko
$$ ----------------------------
$$ | . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . |
$$ | . . . , . . , . . , . . . |
$$ | . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . |
$$ | . . . , . . , . . , . . . |
$$ | . . O O . . . . . . . . . |
$$ | . O . . O . . . . . . . . |
$$ | . . O O . O O O O O O . . |
$$ | X X X X O X X X X X O . . |
$$ | . . X O 3 O X . . X O . . |
$$ | . . X 5 2 1 . . . X . . . |
$$ ---------------------------[/go]


:w4: elsewhere

:w2: is the correct response (almost regardless of the rest of the board) to :b1:. The ko is humungous, and in real life White will not have a ko threat that Black should answer. But White should make the ko, anyway. Making the ko forces Black to make two net plays to connect instead of one. White sacrifices a few stones for an extra play somewhere else. (It is conceivable that there will be no play big enough elsewhere for White to make that sacrifice. However, the possibility that there is is enough for :b1: not to be part of the solution when Black has a sure connection in one net play.) :)

Author:  lefuet [ Tue Jun 14, 2011 4:14 am ]
Post subject:  Re: GoChild Problem

beginner - ko - problem 140

i think there is no need for ko to live or am I missing smth?

Click Here To Show Diagram Code
[go]$$
$$ -----------------
$$ | . . . . . . . |
$$ | . . . . . . . |
$$ | . X . . . . . |
$$ | . . X X X X . |
$$ | X X O O O O X |
$$ | X O . . . O X |
$$ | . . . . . O . |
$$ ----------------[/go]

Author:  Magicwand [ Tue Jun 14, 2011 4:23 am ]
Post subject:  Re: GoChild Problem

lefuet wrote:
beginner - ko - problem 140

i think there is no need for ko to live or am I missing smth?

Click Here To Show Diagram Code
[go]$$
$$ -----------------
$$ | . . . . . . . |
$$ | . . . . . . . |
$$ | . X . . . . . |
$$ | . . X X X X . |
$$ | X X O O O O X |
$$ | X O . . . O X |
$$ | . . . . . O . |
$$ ----------------[/go]

i dont see any way to kill this group
Click Here To Show Diagram Code
[go]$$W
$$ -----------------
$$ | . . . . . . . |
$$ | . . . . . . . |
$$ | . X . . . . . |
$$ | . . X X X X . |
$$ | X X O O O O X |
$$ | X O . . . O X |
$$ | . 1 . . . O . |
$$ ----------------[/go]

Author:  lefuet [ Tue Jun 14, 2011 5:28 am ]
Post subject:  Re: GoChild Problem

thanks, that's what I thought.

but since I have a blind spot with some techniques and a few beginner problems seemed impossible at first glance I wanted to check :)

Author:  Hushfield [ Tue Jun 14, 2011 6:18 am ]
Post subject:  Re: GoChild Problem

Chew Terr wrote:
ninestone wrote:
These connect and cut problems make me feel like I'm too stupid to play Go. I nailed everything up to them, and now I don't get any.
Oh, don't worry, they're really tough. If you have a bad time with them, you can always work on a different set and come back later. That set and some of the endgame sets are particularly merciless.
I can second that. It seems that correct answers that are just a little bit inferior to the chosen solution are also marked wrong. The connecting and cutting set on gochild is indeed quite unforgiving.

Author:  xed_over [ Sat Jun 18, 2011 11:50 am ]
Post subject:  Re: GoChild Problem

judicata wrote:
ninestone wrote:
These connect and cut problems make me feel like I'm too stupid to play Go. I nailed everything up to them, and now I don't get any.


Starting out, I found "connect and capture" and shortage of liberties problems to be difficult to grasp at first--keep practicing and you'll get the hang of it.

I still have problems with the connect and cut problems. Heck, I can't even get past the Entrance level problems.

Its trying to teach me what should be fundamental shapes that I just never learned as a beginner. I'm slowly starting to see and play these shapes in my games.

My favorite cut and connect shape is:
Click Here To Show Diagram Code
[go]$$B cut and connect 31 (black to play)
$$ ----------------------------
$$ | . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . |
$$ | . . . , . . , . . , . . . |
$$ | . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . |
$$ | . . X , . . , . . , . . . |
$$ | . X . . . . . . . . . . . |
$$ | X O X . O . . . . . . . . |
$$ | . O X . . O O . . , . . . |
$$ | O O X . . . . O . . . . . |
$$ | . O X . X . . O . . . . . |
$$ | . O O O . . . O . . . . . |
$$ ---------------------------[/go]

Author:  SoDesuNe [ Sat Jun 18, 2011 1:48 pm ]
Post subject:  Re: GoChild Problem

Click Here To Show Diagram Code
[go]$$Bc cut and connect 31 (black to play)
$$ ----------------------------
$$ | . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . |
$$ | . . . , . . , . . , . . . |
$$ | . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . |
$$ | . . X , . . , . . , . . . |
$$ | . X . . . . . . . . . . . |
$$ | X O X . O . . . . . . . . |
$$ | . O X . . O O . . , . . . |
$$ | O O X . . 1 . O . . . . . |
$$ | . O X . X . . O . . . . . |
$$ | . O O O . . . O . . . . . |
$$ ---------------------------[/go]


If I'm not mistaken : )

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