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
$$Wc Black to fix
$$ ---------------------------------------
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . X O X . . . . . . . . . . . |
$$ | . . . . O X X O X X X 1 . O . . . . . |
$$ | . . . O . X . O O O O . . . . X . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . O . . . . . . . . . . . . X . . |
$$ | . . . . . . . . . . . . . . . . . . . |
[go]$$Bc
$$ ---------------------------------------
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . X O X . 1 . . . . . . . . . |
$$ | . . . . O X X O X X X O . O . . . . . |
$$ | . . . O . X . O O O O . . . . X . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . O . . . . . . . . . . . . X . . |
$$ | . . . . . . . . . . . . . . . . . . . |[/go]
Re: hakuseki's problem collection
Posted: Fri Apr 22, 2022 9:19 am
by hakuseki
Problem 2
Source: 初段になれる詰碁 p.211
$$Bc Black to live
$$ | . . . . . . . . .
$$ | . O . . . . . . .
$$ | . . . . . . . . .
$$ | . O O O . . . . .
$$ | O X X X O O O O .
$$ | . . X O X X X O .
$$ | . . . O . . . . .
$$ --------------------
[go]$$Bc Black to live
$$ | . . . . . . . . .
$$ | . O . . . . . . .
$$ | . . . . . . . . .
$$ | . O O O . . . . .
$$ | O X X X O O O O .
$$ | . . X O X X X O .
$$ | . . . O . . . . .
$$ --------------------[/go]
$$Bc
$$ | . . . . . . . . .
$$ | . O . . . . . . .
$$ | . . . . . . . . .
$$ | . O O O . . . . .
$$ | O X X X O O O O .
$$ | 3 . X O X X X O .
$$ | . 5 . O 1 4 2 . .
$$ --------------------
[go]$$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]
Re: hakuseki's problem collection
Posted: Fri Apr 22, 2022 3:53 pm
by hakuseki
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 . .
$$ | . . . O X O . . O .
$$ | . . . . . . . . . .
$$ ----------------------
[go]$$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 . . . . .
$$ ----------------------
[go]$$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]
Re: hakuseki's problem collection
Posted: Sat Apr 23, 2022 6:22 am
by hakuseki
Problem 4
Source: ひと目の手筋 p.301
$$Bc Black to play
$$ . . . . . . . . . . . . |
$$ . . . . . . . . . X . . |
$$ . . . . . . . . . . . . |
$$ . . O . . O . O O X . . |
$$ . . . . . . . O X X . . |
$$ . O , . . . O X O X . . |
$$ . . . . . . . X O X . . |
$$ . . . . . . . . O . . . |
$$ . . . . . . . . . . . . |
$$ ------------------------
[go]$$Bc
$$ . . . . . . . . . . . . |
$$ . . . . . . . . . X . . |
$$ . . . . . . . . . . . . |
$$ . . . . . . . . X . . . |
$$ . . . . O . O O X . . . |
$$ . . , . . . O X X . . . |
$$ . . . . O O X . . X . . |
$$ . . O . O X X . O . . . |
$$ . . . . . O . 1 . . . . |
$$ ------------------------[/go]
Re: hakuseki's problem collection
Posted: Sat Apr 23, 2022 2:36 pm
by EricBackus
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 . .
$$ | . . . O X O . . O .
$$ | . . . . . . . . . .
$$ ----------------------
[go]$$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 . . . . .
$$ ----------------------
[go]$$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:
$$Bc White still kills all?
$$ | . . . . . . . . . .
$$ | . . O . . . . . . .
$$ | . O . O O O O . . .
$$ | . O X X X X . . . .
$$ | . X X O O X O O . .
$$ | . 3 2 O X O . . O .
$$ | . . . 1 4 . . . . .
$$ ----------------------
[go]$$Bc White still kills all?
$$ | . . . . . . . . . .
$$ | . . O . . . . . . .
$$ | . O . O O O O . . .
$$ | . O X X X X . . . .
$$ | . X X O O X O O . .
$$ | . 3 2 O X O . . O .
$$ | . . . 1 4 . . . . .
$$ ----------------------[/go]
Edit: nevermind
$$Bc Black still has a ko
$$ | . . . . . . . . . .
$$ | . . O . . . . . . .
$$ | . O . O O O O . . .
$$ | . O X X X X . . . .
$$ | . X X O O X O O . .
$$ | . . 2 O X O . . O .
$$ | . . . 1 . 3 . . . .
$$ ----------------------
[go]$$Bc Black still has a ko
$$ | . . . . . . . . . .
$$ | . . O . . . . . . .
$$ | . O . O O O O . . .
$$ | . O X X X X . . . .
$$ | . X X O O X O O . .
$$ | . . 2 O X O . . O .
$$ | . . . 1 . 3 . . . .
$$ ----------------------[/go]
Ko seems to be a blindspot for me
Re: hakuseki's problem collection
Posted: Sun Apr 24, 2022 5:54 am
by hakuseki
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 . |
$$ . . . . O . O O O . |
$$ . . . . . . . . . . |
$$ . . . . . . . . . . |
$$ --------------------
[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]
Re: hakuseki's problem collection
Posted: Sun Apr 24, 2022 8:46 am
by RobertJasiek
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 . .
$$ --------------------
[go]$$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,
$$Bc
$$ | . . . . . . . . .
$$ | . O . . . . . . .
$$ | . . . . . . . . .
$$ | . O O O . . . . .
$$ | O X X X O O O O .
$$ | 5 2 X O X X X O .
$$ | 6 7 3 O 1 . 4 . .
$$ --------------------
[go]$$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.
Re: hakuseki's problem collection
Posted: Sun Apr 24, 2022 10:14 am
by lightvector
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 . |
$$ . . . . O . O O O . |
$$ . . . . . . . . . . |
$$ . . . . . . . . . . |
$$ --------------------
[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.
$$Bc
$$ --------------------
$$ . . . . . . . . . . |
$$ . . . . . 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]$$Wc
$$ --------------------
$$ . . . . . . . . . . |
$$ . . . . . 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.
$$Wc
$$ --------------------
$$ . . . . . . . . . . |
$$ . . . . . 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]$$Wc my thought
$$ ---------------------------------------
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . 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 . |
$$ | . . . . . O . 2 O 4 6 . . . . X X X . |
$$ | . . . . . . . 3 5 . . . . . . . O . . |
$$ | . . O X O . . . . . . . . . . . . . . |
$$ | . X . O . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . X , . . . . . , . . . . . O . . . |[/go]
This variation seems inferior because it gives White too much influence.
Problem 8
Posted: Sun May 29, 2022 5:28 am
by hakuseki
Problem 8
Source: Game with KataGo
$$Bc Black to defend
$$ ---------------------------------------
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . 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]$$Bc Black to defend
$$ ---------------------------------------
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . 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?
$$Bc Defending in sente
$$ ---------------------------------------
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . 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 . . . X . . O X . . . X O O X |
$$ | . X O . 1 O O X . . O O X . . O . O O |
$$ | . X X O . X . X . , . . X . . O . . . |
$$ | . . O X X O X . . . . O O . . O . . . |
$$ | . . . . . . . . . . . . . . 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]$$Bc Defending in sente
$$ ---------------------------------------
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . 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 . . . X . . O X . . . X O O X |
$$ | . X O . 1 O O X . . O O X . . O . O O |
$$ | . X X O . X . X . , . . X . . O . . . |
$$ | . . O X X O X . . . . O O . . O . . . |
$$ | . . . . . . . . . . . . . . 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]
Problem 9
Posted: Wed Jun 15, 2022 1:34 am
by hakuseki
Problem 9
Source: Game with KataGo
$$Wc Are these black stones all connected?
$$ , . . . . . , . . . |
$$ . . . . . . . . . . |
$$ . . . . . . . . . . |
$$ . . . . . . . O . . |
$$ . O . . . . O X . . |
$$ . . . . B . . O . . |
$$ O . . B . . O . . . |
$$ . . O O B . . B . . |
$$ . . . . . B . . . . |
$$ . . . . . . . . . . |
$$ --------------------
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 ).
Problem 11
Posted: Mon Aug 01, 2022 6:16 am
by hakuseki
Problem 11
Source: Game with KataGo
$$Bc Black to play local endgame
$$ . 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 . . . |
$$ ------------------
[go]$$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]
$$Bc Solution
$$ . X . . . . . . . |
$$ O X X . . . X X . |
$$ O O X . . X X O . |
$$ . O O X X . X O . |
$$ . . . O O X O X X |
$$ . . . O X X O O 1 |
$$ . . . . O O . . . |
$$ ------------------
[go]$$Bc Solution
$$ . X . . . . . . . |
$$ 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 1 |
$$ . . . . O O . . . |
$$ ------------------[/go]