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L19 Go Problem Championship: Round 8

https://www.lifein19x19.com/viewtopic.php?t=14158

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L19 Go Problem Championship: Round 8

Posted: Sun Apr 09, 2017 8:29 pm
by Kirby
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:

Posted: Mon Apr 10, 2017 2:51 am
by EdLee
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]

Re: L19 Go Problem Championship: Round 8

Posted: Mon Apr 10, 2017 5:58 am
by Schachus
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
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

Re: L19 Go Problem Championship: Round 8

Posted: Tue Apr 11, 2017 5:38 am
by mongus
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]

Re: L19 Go Problem Championship: Round 8

Posted: Tue Apr 11, 2017 7:57 am
by Cassandra
@ 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 ?

Re: L19 Go Problem Championship: Round 8

Posted: Tue Apr 11, 2017 8:21 am
by Bill Spight
@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]

Re: L19 Go Problem Championship: Round 8

Posted: Tue Apr 11, 2017 9:04 am
by Kirby
@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?

Re: L19 Go Problem Championship: Round 8

Posted: Wed Apr 12, 2017 12:12 pm
by mongus
@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..

Re: L19 Go Problem Championship: Round 8

Posted: Wed Apr 12, 2017 12:25 pm
by mongus
@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]

Re: L19 Go Problem Championship: Round 8

Posted: Wed Apr 12, 2017 1:17 pm
by Cassandra
@ 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 ;-)

Re: L19 Go Problem Championship: Round 8

Posted: Wed Apr 12, 2017 1:27 pm
by Bill Spight
@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. :)

Re: L19 Go Problem Championship: Round 8

Posted: Thu Apr 13, 2017 2:57 am
by mongus
@Bill and @Cassandra
Thankyou, very insightful.

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

Re: L19 Go Problem Championship: Round 8

Posted: Thu Apr 13, 2017 7:12 am
by hyperpape
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]

Re: L19 Go Problem Championship: Round 8

Posted: Thu Apr 13, 2017 7:12 am
by hyperpape
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]

Re: L19 Go Problem Championship: Round 8

Posted: Thu Apr 13, 2017 7:22 am
by Kirby
@hyperpape:
(Includes hint)
Problem 1 is correct; Problem 2 is close. Think about the ordering of your sequence.
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