hakuseki's problem collection

hakuseki · Post by **hakuseki** » Fri Apr 22, 2022 9:09 am

I hope I will be forgiven for starting another study journal when I already have one. Here I will only post problems. The focus is not on super hard problems, but on problems that I feel I should have gotten right but missed. All problems will be black to play.

Problem 1
Source: Game against KataGo

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

hakuseki · Post by **hakuseki** » Fri Apr 22, 2022 9:19 am

Problem 2
Source: 初段になれる詰碁　p.211

Click Here To Show Diagram Code: [go]$$Bc Black to live $$ | . . . . . . . . . $$ | . O . . . . . . . $$ | . . . . . . . . . $$ | . O O O . . . . . $$ | O X X X O O O O . $$ | . . X O X X X O . $$ | . . . O . . . . . $$ --------------------[/go]

hakuseki · Post by **hakuseki** » Fri Apr 22, 2022 3:53 pm

Problem 3
Source: 初段になれる詰碁 p.219

Click Here To Show Diagram Code: [go]$$Bc Black to move $$ | . . . . . . . . . . $$ | . . O . . . . . . . $$ | . O . O O O O . . . $$ | . O X X X X . . . . $$ | . X X O O X O O . . $$ | . . . O X O . . O . $$ | . . . . . . . . . . $$ ----------------------[/go]

hakuseki · Post by **hakuseki** » Sat Apr 23, 2022 6:22 am

Problem 4
Source: ひと目の手筋 p.301

Click Here To Show Diagram Code: [go]$$Bc Black to play $$ . . . . . . . . . . . . | $$ . . . . . . . . . X . . | $$ . . . . . . . . . . . . | $$ . . O . . O . O O X . . | $$ . . . . . . . O X X . . | $$ . O , . . . O X O X . . | $$ . . . . . . . X O X . . | $$ . . . . . . . . O . . . | $$ . . . . . . . . . . . . | $$ ------------------------[/go]

hakuseki · Post by **hakuseki** » Sat Apr 23, 2022 6:35 am

Problem 5
Source: ひと目の手筋 p.299

Click Here To Show Diagram Code: [go]$$Bc Black to play $$ . . . . . . . . . . . . | $$ . . . . . . . . . X . . | $$ . . . . . . . . . . . . | $$ . . . . . . . . X . . . | $$ . . . . O . O O X . . . | $$ . . , . . . O X X . . . | $$ . . . . O O X . . X . . | $$ . . O . O X X . O . . . | $$ . . . . . O . . . . . . | $$ ------------------------[/go]

EricBackus · Post by **EricBackus** » Sat Apr 23, 2022 2:36 pm

hakuseki wrote:Problem 3
Source: 初段になれる詰碁 p.219

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

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

I guess these problems are a little above my level, but I don't understand why this

isn't a refutation of the given solution:

Edit: nevermind

hakuseki · Post by **hakuseki** » Sun Apr 24, 2022 5:54 am

Problem 6
Source: Game with KataGo

Click Here To Show Diagram Code: [go]$$Bc Black to play $$ -------------------- $$ . . . . . . . . . . | $$ . . . . . O O . . . | $$ . . . . O . X O . . | $$ , . O O X . X O . . | $$ . . . X X . . X X . | $$ . . . . . . . . . . | $$ . . . . . . . . . . | $$ . . . . . . . . . . | $$ . . . . . . . . . . | $$ , . . . . . X . . . | $$ . . . . . . . . . . | $$ . . . . . . . . . . | $$ . . . . . . O . . . | $$ . . . . . . X O O X | $$ . . . . . . . X X . | $$ , X . . . X X X O . | $$ . . . . O . O O O . | $$ . . . . . . . . . . | $$ . . . . . . . . . . | $$ --------------------[/go]

RobertJasiek · Post by **RobertJasiek** » Sun Apr 24, 2022 8:46 am

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

E.g., this is insufficient. One must also consider other variations, in particular,

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

and continuations from here as well as 4@5 - 4.

lightvector · Post by **lightvector** » Sun Apr 24, 2022 10:14 am

hakuseki wrote:Problem 6
Source: Game with KataGo

$$Bc Black to play
$$ --------------------
$$ . . . . . . . . . . |
$$ . . . . . O O . . . |
$$ . . . . O . X O . . |
$$ , . O O X . X O . . |
$$ . . . X X . . X X . |
$$ . . . . . . . . . . |
$$ . . . . . . . . . . |
$$ . . . . . . . . . . |
$$ . . . . . . . . . . |
$$ , . . . . . X . . . |
$$ . . . . . . . . . . |
$$ . . . . . . . . . . |
$$ . . . . . . O . . . |
$$ . . . . . . X O O X |
$$ . . . . . . . X X . |
$$ , X . . . X X X O . |
$$ . . . . O . O O O . |
$$ . . . . . . . . . . |
$$ . . . . . . . . . . |
$$ --------------------
Click Here To Show Diagram Code
[go]$$Bc Black to play $$ -------------------- $$ . . . . . . . . . . | $$ . . . . . O O . . . | $$ . . . . O . X O . . | $$ , . O O X . X O . . | $$ . . . X X . . X X . | $$ . . . . . . . . . . | $$ . . . . . . . . . . | $$ . . . . . . . . . . | $$ . . . . . . . . . . | $$ , . . . . . X . . . | $$ . . . . . . . . . . | $$ . . . . . . . . . . | $$ . . . . . . O . . . | $$ . . . . . . X O O X | $$ . . . . . . . X X . | $$ , X . . . X X X O . | $$ . . . . O . O O O . | $$ . . . . . . . . . . | $$ . . . . . . . . . . | $$ --------------------[/go]

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

Yep,

Because black has the marked stones in this shape, black's counter-atari is highly effective for dealing the cut, which is why black should have no fear of playing double hane.

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

White is deeply surrounded.

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

Or a bit more fancy for black, like this:

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

Black has no fear of the cutting point below because White's corner shape is not solid enough. If white cuts, black easily pushes through, severely damaging White's marked stone and making the cut at "a" for black work next.

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

hakuseki · Post by **hakuseki** » Sun May 08, 2022 5:51 am

Problem 7
Source: Game with KataGo

Click Here To Show Diagram Code: [go]$$Wc Black to respond after :w1: $$ --------------------------------------- $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . X . 1 O . . . . . . . . . . | $$ | . . . . O X . X O X X X . X O O X O . | $$ | . . . O . O X X X O O . . X . X O O . | $$ | . . . . . O . . O . . . . . . X X X . | $$ | . . . . . . . . . . . . . . . . O . . | $$ | . . O X O . . . . . . . . . . . . . . | $$ | . X . O . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . X , . . . . . , . . . . . O . . . |[/go]

jlt · Post by **jlt** » Sun May 08, 2022 7:48 am

I got this one wrong too

hakuseki · Post by **hakuseki** » Sun May 29, 2022 5:28 am

Problem 8
Source: Game with KataGo

Click Here To Show Diagram Code: [go]$$Bc Black to defend $$ --------------------------------------- $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . X . X . . . . . . X O O . O . . | $$ | . . . . O X . X O X . X . X O O . O . | $$ | . . O O . O X . X , . . . X . X O O . | $$ | . X X O . O . O O . . . . . . X X X X | $$ | . . X X O . . . . . O X . . . X O O X | $$ | . X O X O . . . . . O X . . . X O X X | $$ | . X . O . . . B . . O X . . . X O O X | $$ | . X O . . O O B . . O O X . . O . O O | $$ | . X X O . X a B . , . . X . . O . . . | $$ | . . O X X O X c . . . O O . . O . . . | $$ | . . . . . b . . . . . . . . X . . . . | $$ | . . . X . . . . . . O . . . . . O . . | $$ | . . . . X . . O . X . . . . . O X . . | $$ | . . . . . O O . O X . . . X . . O . . | $$ | . . . X X O . O X , . . X . . O . . . | $$ | . X X X O O O X X X . X O X . O . . . | $$ | . O X O . O . O X O X . . X O . . . . | $$ | . . O . O . . O O . O . . . . . . . . | $$ ---------------------------------------[/go]

White is threatening the sequence a-b-c, cutting off the three marked stones. How can black defend?

hakuseki · Post by **hakuseki** » Wed Jun 15, 2022 1:34 am

Problem 9
Source: Game with KataGo

Click Here To Show Diagram Code: [go]$$Wc Are these black stones all connected? $$ , . . . . . , . . . | $$ . . . . . . . . . . | $$ . . . . . . . . . . | $$ . . . . . . . O . . | $$ . O . . . . O X . . | $$ . . . . B . . O . . | $$ O . . B . . O . . . | $$ . . O O B . . B . . | $$ . . . . . B . . . . | $$ . . . . . . . . . . | $$ --------------------[/go]

hakuseki · Post by **hakuseki** » Wed Jun 15, 2022 5:07 am

Problem 10
Source: Game with KataGo

Visualization problem: Read as many sequences as you like. If the solution is among the sequences you considered, you pass the test.

Click Here To Show Diagram Code: [go]$$Bc White to read 3 moves $$ --------------------------------------- $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . O . . . . . . . . . . . . | $$ | . . . O . . . . . , . . . . . X . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . X . . . . . . . . . . . . . O . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . X . . . . . , . . . . . , . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . O . . | $$ | . . . . . . . . . . O . . . . O X X . | $$ | . . . . . . . . . 1 . . . X . . O O . | $$ | . . . X . . . . . O . X X . . O . . . | $$ | . . . . . . . X . . O O O X . . X . . | $$ | . . . . . . . . . . . . . . X . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ ---------------------------------------[/go]

Click Here To Show Diagram Code: [go]$$Wc Best sequence according to KataGo $$ --------------------------------------- $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . O . . . . . . . . . . . . | $$ | . . . O . . . . . , . . . . . X . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . X . . . . . . . . . . . . . O . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . X . . . . . , . . . . . , . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . O . . | $$ | . . . . . . . . . . O . . . . O X X . | $$ | . . . . . . . . . X 1 . . X . . O O . | $$ | . . . X . . . . 3 O 2 X X . . O . . . | $$ | . . . . . . . X . . O O O X . . X . . | $$ | . . . . . . . . . . . . . . X . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ ---------------------------------------[/go]

I'm experimenting with this problem format. The problem is considered "solved" if you thought of the right sequence, even if you don't uniquely single it out as the best sequence.
Why this format?
On the one hand, I don't think that, relying only upon my own intuition, I would be able to confidently state that

is the best move.
On the other hand, I think if I had actually visualized the sequence

, I would have gone ahead and played

.
Therefore most of the benefit can be had by just ensuring that I actually read the sequence

(in the game I stopped reading at

).

hakuseki · Post by **hakuseki** » Mon Aug 01, 2022 6:16 am

Problem 11
Source: Game with KataGo

Click Here To Show Diagram Code: [go]$$Bc Black to play local endgame $$ . X . . . . . . . | $$ O X X . . . X X . | $$ O O X . . X X O . | $$ . O O X X . X O . | $$ . . . O O X O X X | $$ . . . O X X O O . | $$ . . . . O O . . . | $$ ------------------[/go]

Life In 19x19

hakuseki's problem collection

hakuseki's problem collection

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Problem 7

Re: hakuseki's problem collection

Problem 8

Problem 9

Problem 10

Problem 11