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Offline Knotwilg
 Post subject: Dieter's ABC of mistakes - 4
Post #1 Posted: Thu Apr 01, 2021 8:13 am 
Oza
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Click Here To Show Diagram Code
[go]$$B Mistake 4
$$ ---------------------------------------
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . X X X X . |
$$ | . X O X . . . . . . . . X X O X . . X |
$$ | . X O X . . X . . , . O X O O O X X . |
$$ | . O X X . . . c . X X O O X O X O O . |
$$ | O . O O . O . . . X O O . . O X O . . |
$$ | . O . . . . . X X O 1 a . . O X O . . |
$$ | . . . . X O O b O O . . X . . X . . . |
$$ | . . . . X . X O . . . . . O X X X O . |
$$ | . X X , . . X O . , . . . O O X O . . |
$$ | . O X . . . X O . O X . . . . O O . . |
$$ | O . O X . . X . . X O . . . . . . . . |
$$ | . O O . . . . . . X O . . . . . . . . |
$$ | . . . . . . . . . X O . O . . . . . . |
$$ | . . . O . . . . . O X O . . . . . . . |
$$ | . . O , . . . . . , X X O O O O O O . |
$$ | . . O X . . X . . . . X X O X X X X . |
$$ | . X X . . . . . . . . . . X . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ ---------------------------------------[/go]


White has a big lead (33 points). Black is trying to stage an upset. White lost 10 points by making the wrong choice between a, b and c.
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Offline jlt
 Post subject: Re: Dieter's ABC of mistakes - 4
Post #2 Posted: Thu Apr 01, 2021 10:15 am 
Gosei
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Let's try. White's group on the left doesn't have two eyes, so a move at "b" would save it.

Edit: move :w8: in the diagram below is wrong!

Click Here To Show Diagram Code
[go]$$Bc No problem, White is really connected.
$$ ---------------------------------------
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . X X X X . |
$$ | . X O X . . . . . . . . X X O X . . X |
$$ | . X O X . . X . . , . O X O O O X X . |
$$ | . O X X . . . c . X X O O X O X O O . |
$$ | O . O O 4 O 7 8 . X O O . . O X O . . |
$$ | . O . . 3 5 6 X X O 1 a . . O X O . . |
$$ | . . . . X O O 2 O O . . X . . X . . . |
$$ | . . . . X . X O . . . . . O X X X O . |
$$ | . X X , . . X O . , . . . O O X O . . |
$$ | . O X . . . X O . O X . . . . O O . . |
$$ | O . O X . . X . . X O . . . . . . . . |
$$ | . O O . . . . . . X O . . . . . . . . |
$$ | . . . . . . . . . X O . O . . . . . . |
$$ | . . . O . . . . . O X O . . . . . . . |
$$ | . . O , . . . . . , X X O O O O O O . |
$$ | . . O X . . X . . . . X X O X X X X . |
$$ | . X X . . . . . . . . . . X . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ ---------------------------------------[/go]


So the question is whether :b1: threatens something. Clearly Black doesn't have enough space to make two eyes, so the only way for :b1: to live is to kill one of the white strings.

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


If Black plays :b3: at "a" or at any of the "d", then White can just capture the triangled stone and is fine.

Click Here To Show Diagram Code
[go]$$Bc
$$ ---------------------------------------
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . X X X X . |
$$ | . X O X . . . . . . . . X X O X . . X |
$$ | . X O X . . X . . , . O X O O O X X . |
$$ | . O X X . . . c . X X O O Y O X O O . |
$$ | O . O O . O . . . X O O . 5 O X O . . |
$$ | . O . . . . . X X O 1 a . d O X O . . |
$$ | . . . . X O O 2 O O . . X 3 4 X 6 . . |
$$ | . . . . X . X O . . . . . O X X X O . |
$$ | . X X , . . X O . , . . . O O X O . . |[/go]


"a" and "d" are miai. Same thing if :b3: and :b5: are interchanged.

Click Here To Show Diagram Code
[go]$$Bc No problem either
$$ ---------------------------------------
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . X X X X . |
$$ | . X O X . . . . . . . . X X O X . . X |
$$ | . X O X . . X . . , . O X O O O X X . |
$$ | . O X X . . . c . X X O O Y O X O O . |
$$ | O . O O . O . . . X O O . 6 O X O . . |
$$ | . O . . . . . X X O 1 a . 5 O X O . . |
$$ | . . . . X O O 2 O O . . X 4 3 X . . . |
$$ | . . . . X . X O . . . . . O X X X O . |
$$ | . X X , . . X O . , . . . O O X O . . |[/go]


So I don't think :b1: was a threat. The correct move must be "b" or "c", but I don't understand "c". What if Black cuts?

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


Perhaps :w2: aims at using shortage of liberties but I don't understand how, variations seem complicated.


Conclusion: I would play "b", it's clean and safe. Anyway White is leading, there is no need to search for complications.


Last edited by jlt on Thu Apr 01, 2021 2:40 pm, edited 2 times in total.
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Offline Harleqin
 Post subject: Re: Dieter's ABC of mistakes - 4
Post #3 Posted: Thu Apr 01, 2021 2:01 pm 
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jlt, take a look at your first diagram. Black can still cut. There is a better :w8:, though. However, even if White is cut, the group can live. How? What is the next problem then?

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A good system naturally covers all corner cases without further effort.
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Offline jlt
 Post subject: Re: Dieter's ABC of mistakes - 4
Post #4 Posted: Thu Apr 01, 2021 2:35 pm 
Gosei
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Oops I hallucinated. Let me try again.

Click Here To Show Diagram Code
[go]$$Bc No problem, White is really connected.
$$ ---------------------------------------
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . X X X X . |
$$ | . X O X . . . . . . . . X X O X . . X |
$$ | . X O X . . X . . e . O X O O O X X . |
$$ | . O X X . . 8 0 . X X O O X O X O O . |
$$ | O . O O 4 O 7 9 d X O O . . O X O . . |
$$ | . O . . 3 5 6 X X O 1 a . . O X O . . |
$$ | . . . . X O O 2 O O . . X . . X . . . |
$$ | . . . . X . X O . . . . . O X X X O . |
$$ | . X X , . . X O . , . . . O O X O . . |
$$ | . O X . . . X O . O X . . . . O O . . |
$$ | O . O X . . X . . X O . . . . . . . . |
$$ | . O O . . . . . . X O . . . . . . . . |
$$ | . . . . . . . . . X O . O . . . . . . |
$$ | . . . O . . . . . O X O . . . . . . . |
$$ | . . O , . . . . . , X X O O O O O O . |
$$ | . . O X . . X . . . . X X O X X X X . |
$$ | . X X . . . . . . . . . . X . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ ---------------------------------------[/go]


If Black d then White e.

If White is disconnected then I think that White can live like this but this weakens the bottom left group. In addition the situation of the white marked group is becoming unclear.

Click Here To Show Diagram Code
[go]$$Bc
$$ ---------------------------------------
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . X X X X . |
$$ | . X O X . . . . . . . . X X O X . . X |
$$ | . X O X . . X . . , . O X O O O X X . |
$$ | . O X X . . . . . X X O O X O X O O . |
$$ | O . O O . O . . . X O O . . O X O . . |
$$ | . O . . . . . X X Q 1 . . . O X O . . |
$$ | . . 6 . X O O 3 Q Q . . X . . X . . . |
$$ | . 4 . . X . X Q . . . . . O X X X O . |
$$ | 5 X X , . . X Q . , . . . O O X O . . |
$$ | . O X . . . X Q . Q X . . . . O O . . |
$$ | O . O X . . X . . X O . . . . . . . . |
$$ | . O O . . . . . . X O . . . . . . . . |
$$ | . . . . . . . . . X O . O . . . . . . |
$$ | . . . O . . . . . O X O . . . . . . . |
$$ | . . O , . . . . . , X X O O O O O O . |
$$ | . . O X . . X . . . . X X O X X X X . |
$$ | . X X . . . . . . . . . . X . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ ---------------------------------------[/go]
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Offline skydyr
 Post subject: Re: Dieter's ABC of mistakes - 4
Post #5 Posted: Thu Apr 01, 2021 5:53 pm 
Oza

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jlt wrote:

If White is disconnected then I think that White can live like this but this weakens the bottom left group. In addition the situation of the white marked group is becoming unclear.

Click Here To Show Diagram Code
[go]$$Bc
$$ ---------------------------------------
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . X X X X . |
$$ | . X O X . . . . . . . . X X O X . . X |
$$ | . X O X . . X . . , . O X O O O X X . |
$$ | . O X X . . . . . X X O O X O X O O . |
$$ | O . O O . O . . . X O O . . O X O . . |
$$ | . O . . . . . X X Q 1 . . . O X O . . |
$$ | . . 6 . X O O 3 Q Q . . X . . X . . . |
$$ | . 4 . . X . X Q . . . . . O X X X O . |
$$ | 5 X X , . . X Q . , . . . O O X O . . |
$$ | . O X . . . X Q . Q X . . . . O O . . |
$$ | O . O X . . X . . X O . . . . . . . . |
$$ | . O O . . . . . . X O . . . . . . . . |
$$ | . . . . . . . . . X O . O . . . . . . |
$$ | . . . O . . . . . O X O . . . . . . . |
$$ | . . O , . . . . . , X X O O O O O O . |
$$ | . . O X . . X . . . . X X O X X X X . |
$$ | . X X . . . . . . . . . . X . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ ---------------------------------------[/go]

Don't forget that white passed for :w2: in your diagram.
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Offline jlt
 Post subject: Re: Dieter's ABC of mistakes - 4
Post #6 Posted: Thu Apr 01, 2021 10:31 pm 
Gosei
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Yes I wasn't clear. If :w2: is a pass then :b3: at "b" creates two problems. Therefore :w2: at "b" is a good move, since it solves both problems.
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Offline Knotwilg
 Post subject: Re: Dieter's ABC of mistakes - 4
Post #7 Posted: Fri Apr 02, 2021 3:17 am 
Oza
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"Solution"

There was indeed no reason to answer :b1: at "a". Katago's preference is :w2: as it indirectly protects against a cut at "b" - White will capture the cutting stones at "d" if Black cuts - while poking at Black's shape. The dull connection at "b" is only a few points worse and good enough to keep the big advantage.
Click Here To Show Diagram Code
[go]$$B Mistake 4 - better answer
$$ ---------------------------------------
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . X X X X . |
$$ | . X O X . . . . . . . . X X O X . . X |
$$ | . X O X . . X . . , . O X O O O X X . |
$$ | . O X X . . . 2 . X X O O X O X O O . |
$$ | O . O O . O . . d X O O . . O X O . . |
$$ | . O . . . . . X X O 1 a . . O X O . . |
$$ | . . . . X O O b O O . . X . . X . . . |
$$ | . . . . X . X O . . . . . O X X X O . |
$$ | . X X , . . X O . , . . . O O X O . . |
$$ | . O X . . . X O . O X . . . . O O . . |
$$ | O . O X . . X . . X O . . . . . . . . |
$$ | . O O . . . . . . X O . . . . . . . . |
$$ | . . . . . . . . . X O . O . . . . . . |
$$ | . . . O . . . . . O X O . . . . . . . |
$$ | . . O , . . . . . , X X O O O O O O . |
$$ | . . O X . . X . . . . X X O X X X X . |
$$ | . X X . . . . . . . . . . X . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ ---------------------------------------[/go]
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