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 Post subject: L19 Go Problem Championship: Round 8
Post #1 Posted: Sun Apr 09, 2017 8:29 pm 
Judan

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Welcome to Round 8 of the L19 Go Problem Championship.

All problems are black to play. As usual, provide your solutions either via hide tags, or direct private message to me.

Problem 1 (3 points)
Click Here To Show Diagram Code
[go]$$Bc
$$ ----------------
$$ | . . . O . . . .
$$ | X O X X O . . .
$$ | . . X O . O . .
$$ | X X O O . . . .
$$ | O O . . . . . .
$$ | . . . . . . . .[/go]


Problem 2 (6 points)
Click Here To Show Diagram Code
[go]$$Bc
$$ ---------------------
$$ . . . . . X . . . . . |
$$ . . O . . O X X . X O |
$$ . O . O . O X . X X O |
$$ . O X X X X X O X O . |
$$ . O O O O O O . O O . |
$$ . . . . . . . . . . . |[/go]


Problem 3 (9 points)
Click Here To Show Diagram Code
[go]$$Bc
$$ | . . . . . . . . . . .
$$ | . . . . . . . . . . .
$$ | . O O O O . . . . . .
$$ | . X O X X O O O O . .
$$ | . O . , . X X . . O .
$$ | O . X . . O . X X O .
$$ | . O X O . . . . . O .
$$ | . O . . . . . X . O .
$$ ----------------------[/go]


Have fun! :salute:

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Post #2 Posted: Mon Apr 10, 2017 2:51 am 
Judan
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Click Here To Show Diagram Code
[go]$$B Life
$$ -----------------
$$ | . 1 . O . . . .
$$ | X O X X O . . .
$$ | . . X O . O . .
$$ | X X O O . . . .
$$ | O O . . . . . .
$$ | . . . . . . . .[/go]
Click Here To Show Diagram Code
[go]$$B Oops
$$ -----------------
$$ | . 2 . O . . . .
$$ | X O X X O . . .
$$ | . 1 X O . O . .
$$ | X X O O . . . .
$$ | O O . . . . . .
$$ | . . . . . . . .[/go]
First feeling: :study:
Click Here To Show Diagram Code
[go]$$B
$$ -----------------------
$$ . . . . . X . . . . . |
$$ . . O 1 . O X X . X O |
$$ . O . O . O X . X X O |
$$ . O X X X X X O X O . |
$$ . O O O O O O . O O . |
$$ . . . . . . . . . . . |[/go]

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

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 Post subject: Re: L19 Go Problem Championship: Round 8
Post #3 Posted: Mon Apr 10, 2017 5:58 am 
Dies with sente

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Kirby wrote:
Welcome to Round 8 of the L19 Go Problem Championship.
Problem 1 (3 points)
Click Here To Show Diagram Code
[go]$$Bc
$$ ----------------
$$ | . . . O . . . .
$$ | X O X X O . . .
$$ | . . X O . O . .
$$ | X X O O . . . .
$$ | O O . . . . . .
$$ | . . . . . . . .[/go]


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

2 eyes at a and where the white stone is. The following would be wrong:
Click Here To Show Diagram Code
[go]$$Bc
$$ ----------------
$$ | . 2 b O . . . .
$$ | X O X X O . . .
$$ | . 1 X O . O . .
$$ | X X O O . . . .
$$ | O O . . . . . .
$$ | . . . . . . . .[/go]

and black cant block at b due to shortage of liberties
Quote:
Problem 2 (6 points)
Click Here To Show Diagram Code
[go]$$Bc
$$ ---------------------
$$ . . . . . X . . . . . |
$$ . . O . . O X X . X O |
$$ . O . O . O X . X X O |
$$ . O X X X X X O X O . |
$$ . O O O O O O . O O . |
$$ . . . . . . . . . . . |[/go]


It would appear, I had a lot of miscalculations in problem 2 and I should clear up my thoughts before posting.

For problem 3, I need to consider it for a while...


Edit: ooops, this was unhidden, because I meant to send it as a PM to Kirby... :( I hope nobody saw it, I'm sorry

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 Post subject: Re: L19 Go Problem Championship: Round 8
Post #4 Posted: Tue Apr 11, 2017 5:38 am 
Dies with sente

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Problem 1

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




Problem 2

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


or

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

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 Post subject: Re: L19 Go Problem Championship: Round 8
Post #5 Posted: Tue Apr 11, 2017 7:57 am 
Lives in gote
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@ mongus

Problem 2

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


Did you consider White's descent to 4 at the left ?

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 Post subject: Re: L19 Go Problem Championship: Round 8
Post #6 Posted: Tue Apr 11, 2017 8:21 am 
Judan

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@mongus

I see that Cassandra beat me to it. Here is another thought. :)

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

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 Post subject: Re: L19 Go Problem Championship: Round 8
Post #7 Posted: Tue Apr 11, 2017 9:04 am 
Judan

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@EdLee:
Looking good so far. I'll wait for elaboration on the second two.


@Schachus:
Problem 1 looks good.


@mongus:
Looks good so far. Do you have a response for either of Cassandra's or Bill's replies?

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 Post subject: Re: L19 Go Problem Championship: Round 8
Post #8 Posted: Wed Apr 12, 2017 12:12 pm 
Dies with sente

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@Bill

Good question, I thought it was easy :

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


ad then

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




But then I realised White could try to be clever,

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



Click Here To Show Diagram Code
[go]$$Bc
$$ ---------------------
$$ . . . O O . O . . . . |
$$ . . O X X 8 X X . X O |
$$ . O . O X . X . X X O |
$$ . O X X X X X O X O . |
$$ . O O O O O O . O O . |
$$ . . . . . . . . . . . |[/go]


All the white stones are connected to the outside.

But eventually I noticed this :


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



This gives me one eye.

If White tries to take my other one, I can kill them all :

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


If she doesn't :


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


I take the eye.


@Cassandra - I am still contemplating your conundrum..


This post by mongus was liked by: Bill Spight
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 Post subject: Re: L19 Go Problem Championship: Round 8
Post #9 Posted: Wed Apr 12, 2017 12:25 pm 
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@Cassandra

That perplexed me, but I think I have it

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


White has to play 6, otherwise I can connect and then capture the three stones. This gives me time to play in the vital spot to take my eyes :



Click Here To Show Diagram Code
[go]$$Bc
$$ ---------------------
$$ . . O . O X X . 7 . . |
$$ . . O . O O X X . X O |
$$ . O . O . O X . X X O |
$$ . O X X X X X O X O . |
$$ . O O O O O O . O O . |
$$ . . . . . . . . . . . |[/go]

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 Post subject: Re: L19 Go Problem Championship: Round 8
Post #10 Posted: Wed Apr 12, 2017 1:17 pm 
Lives in gote
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@ mongus

Well done !

However, ...
mongus wrote:

...

If she doesn't :

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

I take the eye.


Click Here To Show Diagram Code
[go]$$Wc
$$ ---------------------
$$ . . . O O . O . . . . |
$$ . 1 O X X O X X . X O |
$$ . O X . X O X . X X O |
$$ . O X X X X X O X O . |
$$ . O O O O O O . O O . |
$$ . . . . . . . . . . . |[/go]

I want to live with more than only three points of territory !

+ + + + + + + + + + +

EDIT:

As Bill showed you the answer -- in principle -- in his posting below:

From here on, realizing that White suffers from a shortage of liberties at the top, enabling you to capture three of her stones, very likely you would have found out that you could capture these stones a bit earlier.

Such a shortage of liberties is very important, but apparently often some kind of blind spot ;-)

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Last edited by Cassandra on Wed Apr 12, 2017 1:43 pm, edited 1 time in total.
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 Post subject: Re: L19 Go Problem Championship: Round 8
Post #11 Posted: Wed Apr 12, 2017 1:27 pm 
Judan

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@mongus

Click Here To Show Diagram Code
[go]$$Bc
$$ ---------------------
$$ . . . 6 2 . 4 7 . . . |
$$ W . O 1 5 O X X . X O |
$$ . O . O 3 O X . X X O |
$$ . O X X X X X O X O . |
$$ . O O O O O O . O O . |
$$ . . . . . . . . . . . |[/go]


One to remember. :)

Note that it works even if White has the :wc: stone.

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


Note that :b2: is unnecessary. :)

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 Post subject: Re: L19 Go Problem Championship: Round 8
Post #12 Posted: Thu Apr 13, 2017 2:57 am 
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@Bill and @Cassandra

Thankyou, very insightful.

Yes, liberty shortage problems seem to be the ones I understand the least.

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 Post subject: Re: L19 Go Problem Championship: Round 8
Post #13 Posted: Thu Apr 13, 2017 7:12 am 
Oza

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Problem 1
Click Here To Show Diagram Code
[go]$$Bc
$$ ----------------
$$ | . 1 . O . . . .
$$ | X O X X O . . .
$$ | . . X O . O . .
$$ | X X O O . . . .
$$ | O O . . . . . .
$$ | . . . . . . . .[/go]


Problem 2
My thought was: Black threatens to make two eyes.
Click Here To Show Diagram Code
[go]$$Bc
$$ ---------------------
$$ . . . b . X 1 . 2 . . |
$$ . . O 3 a O X X . X O |
$$ . O d O c O X . X X O |
$$ . O X X X X X O X O . |
$$ . O O O O O O . O O . |
$$ . . . . . . . . . . . |[/go]

a is met by b, c by d.

However, we have to verify that there are two eyes after the capture.

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


Click Here To Show Diagram Code
[go]$$Bc
$$ ---------------------
$$ . . . 5 . X 1 . 2 . . |
$$ . . O 3 4 O X X . X O |
$$ . O 6 O 7 O X . X X O |
$$ . O X X X X X O X O . |
$$ . O O O O O O . O O . |
$$ . . . . . . . . . . . |[/go]

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 Post subject: Re: L19 Go Problem Championship: Round 8
Post #14 Posted: Thu Apr 13, 2017 7:12 am 
Oza

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Problem 1
Click Here To Show Diagram Code
[go]$$Bc
$$ ----------------
$$ | . 1 . O . . . .
$$ | X O X X O . . .
$$ | . . X O . O . .
$$ | X X O O . . . .
$$ | O O . . . . . .
$$ | . . . . . . . .[/go]


Problem 2
My thought was: Black threatens to make two eyes.
Click Here To Show Diagram Code
[go]$$Bc
$$ ---------------------
$$ . . . b . X 1 . 2 . . |
$$ . . O 3 a O X X . X O |
$$ . O d O c O X . X X O |
$$ . O X X X X X O X O . |
$$ . O O O O O O . O O . |
$$ . . . . . . . . . . . |[/go]

a is met by b, c by d.

However, we have to verify that there are two eyes after the capture.

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


Black is dead on this line.
Click Here To Show Diagram Code
[go]$$Bc
$$ ---------------------
$$ . . . 5 . X 1 . 2 . . |
$$ . . O 3 4 O X X . X O |
$$ . O 6 O 7 O X . X X O |
$$ . O X X X X X O X O . |
$$ . O O O O O O . O O . |
$$ . . . . . . . . . . . |[/go]

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 Post subject: Re: L19 Go Problem Championship: Round 8
Post #15 Posted: Thu Apr 13, 2017 7:22 am 
Judan

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@hyperpape:
(Includes hint)
Problem 1 is correct; Problem 2 is close. Think about the ordering of your sequence.

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 Post subject: Re: L19 Go Problem Championship: Round 8
Post #16 Posted: Fri Apr 14, 2017 12:54 am 
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Click Here To Show Diagram Code
[go]$$Bc
$$ ----------------
$$ | . 1 . O . . . .
$$ | X O X X O . . .
$$ | . . X O . O . .
$$ | X X O O . . . .
$$ | O O . . . . . .
$$ | . . . . . . . .[/go]

2.
Click Here To Show Diagram Code
[go]$$Bc
$$ ---------------------
$$ . . 4 3 6 X 5 . 7 . . |
$$ . . O 1 2 O X X . X O |
$$ . O . O . O X . X X O |
$$ . O X X X X X O X O . |
$$ . O O O O O O . O O . |
$$ . . . . . . . . . . . |[/go]


Variation:

Click Here To Show Diagram Code
[go]$$Bc
$$ ---------------------
$$ . . 4 3 7 X 5 . 6 . . |
$$ . . O 1 2 O X X . X O |
$$ . O . O . O X . X X O |
$$ . O X X X X X O X O . |
$$ . O O O O O O . O O . |
$$ . . . . . . . . . . . |[/go]


Variation:
Click Here To Show Diagram Code
[go]$$Bc
$$ ---------------------
$$ . . . . 2 X 3 . 4 . . |
$$ . . O 1 5 O X X . X O |
$$ . O . O . O X . X X O |
$$ . O X X X X X O X O . |
$$ . O O O O O O . O O . |
$$ . . . . . . . . . . . |[/go]

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 Post subject: Re: L19 Go Problem Championship: Round 8
Post #17 Posted: Sun Apr 16, 2017 10:15 pm 
Judan

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@gamesorry:
Looks correct.

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 Post subject: Re: L19 Go Problem Championship: Round 8
Post #18 Posted: Sun Apr 16, 2017 10:22 pm 
Judan

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Solutions and updated leader board are given below.

Problem 1


Problem 2


Problem 3


Leaderboard
  1. gamesorry - 110
  2. Schachus - 68
  3. EdLee - 66
  4. dfan - 52
  5. Shaddy - 49
  6. hyperpape - 23
  7. mongus - 19
  8. Lanrose - 16
  9. jeromie - 13

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