Life In 19x19

The theme is opening study with KataGo, although I may include other topics. My intention is to play 1,000 openings against the Policy Weighted AI in KaTrain. The goal is not to win, but to avoid mistakes. I won't be posting the full openings here, only the main ideas I take away from each review. I'll number the games in order of posting, which is not necessarily chronological order (I have some saved up reviews I may post about later).

Some moves are deliberate style choices, which I won't regard as mistakes even if KataGo penalizes them. E.g. recently I play 3-3 fairly often in my openings.

I'll try to generalize a bit, but I may overgeneralize. I'd be delighted to hear disagreements, especially if you can offer counterexample positions.

Game 1, position 1

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[go]$$Bc
$$ ---------------------------------------
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . O , b . . . . , . . . . a , X . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . , . . . . . , . . . . . , . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . , . . . . . , . . . . . X . . . |
$$ | . . c . O . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ ---------------------------------------[/go]

Here I played a, but b is a bit better and c is the best.

5-3 is a worse opening than 3-4. So we shouldn't allow the opponent to "fix the mistake" by making an enclosure. This is more important than making or preventing an enclosure from a 3-4 stone.

Game 1, position 2

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[go]$$Bc
$$ ---------------------------------------
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . O O X . . . a . . . . . . . . . |
$$ | . . O , X X . . . , . . . . X , X . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . O . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . , . . . . . , . . . . . , . . . |[/go]

This joseki should be finished with a low extension, given the upper-right enclosure.

Game 1, position 3

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[go]$$Bc
$$ ---------------------------------------
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . O O X . a . . . . . . . . . . . |
$$ | . . O , X X . O . X . . . . X , X . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . O . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . , . . . . . , . . . . . , . . . |[/go]

Instead, black played the high extension and white invaded. If this happens, black should force the connection at a.

Game 2, position 1

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[go]$$Wc
$$ | . . . , . . . . . , . . . . . , . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . O . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . X . . |
$$ | . . . O . . . . . X . . . . . . . . . |
$$ | . . O , O X . . . , . . b . . X . . . |
$$ | . . . O . X . . . a . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ ---------------------------------------[/go]

This position is a bit peculiar, but white would like to invade this framework. How to proceed? I thought a looks like a vital point to complete the framework, but I was too timid to invade there and played b instead, allowing black to seize a.

Continuation

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[go]$$Wc
$$ | . . . , . . . . . , . . . . . , . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . O . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . X . . |
$$ | . . . O . . . . . X . . . . . . . . . |
$$ | . . O , O X . . . , . . . . . X . . . |
$$ | . . . O . X . . . 3 . . . . . . . . . |
$$ | . . . . . . . . . . . . . . 1 2 . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ ---------------------------------------[/go]

KataGo recommended this sequence. is a probe. If black defends the corner, then white plays at the vital point.

Game 2, position 2

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[go]$$Bc
$$ --------------------
$$ . . . . . . . . . . |
$$ . . . . . . . . . . |
$$ . . . . 1 a . O . . |
$$ , . . . . . , . . . |
$$ . . . . . . . b . . |
$$ . . . . . . 2 . . . |
$$ . . . . . . . . . . |
$$ . . . . . . . . . . |
$$ . . . . . . . . . . |
$$ , . . . . . , . . . |[/go]

In response to black approaching the 3-3 point at , I haven't always been sure which extension to play. Based on KataGo's feedback I'll default to in the future. If the approach is instead at a, then respond at b.

This time my friend and I were studying the opening together. We played black against the AI.

Game 3, position 1

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[go]$$Bc
$$ ---------------------------------------
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . 5 . . . . |
$$ | . . . 2 . . . . . , . . . . . a 1 b . |
$$ | . . . . . . . . . . . . . . . c 6 d . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . , . . . . . , . . . . . , . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . , . . . . . , . . . . . , 4 . . |
$$ | . . 3 . . . . . . . . . . . e . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ ---------------------------------------[/go]

KataGo says should be at e, but let's focus on how black should respond to . I'd always thought that a–d are all reasonable moves, and indeed Josekipedia lists all four moves. My friend and I chose to play at d. But it seems that d is a terrible move!

Continuation

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[go]$$Bc
$$ ---------------------------------------
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . X . . . . |
$$ | . . . O . . . . . , . . . . . , X 3 . |
$$ | . . . . . . . . . . . . . . . 1 O . . |
$$ | . . . . . . . . . . . . . . . . 2 . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . , . . . . . , . . . . . 4 . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . , . . . . . , . . . . . , O . . |
$$ | . . X . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ ---------------------------------------[/go]

is the correct move, after which we may expect the continuation shown above. KataGo's preference seems strong enough that, until I find a counterexample in play, I will assume this is the best joseki choice regardless of the outside board situation.

Game 3, position 2

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[go]$$Bc
$$ ---------------------
$$ | . . . . . . . . . .
$$ | . . . . . X . . . .
$$ | . 3 X X X O 1 . . .
$$ | . . O O O 2 a . . ,
$$ | . . . . . . b . 4 .
$$ | . . . . . . . . . .
$$ | . . . . . . . . . .
$$ | . . . . . . . . . .
$$ | . . . . . . . . . .
$$ | . . . , . . . . . ,[/go]

A 3-3 invasion joseki was played, ending with . We couldn't think of a good local follow-up for black. We thought about a, but if white responds at b we thought the result looks good for white, so we decided to tenuki.

Continuation

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[go]$$Bc
$$ ---------------------
$$ | . . . . . . . . . .
$$ | . . . . . X . . . .
$$ | . X X X X O X 1 . .
$$ | . . O O O O a . . ,
$$ | . . . . . . . b O .
$$ | . . . . . . . . . .
$$ | . . . . . . . . . .
$$ | . . . . . . . . . .
$$ | . . . . . . . . . .
$$ | . . . , . . . . . ,[/go]

However, black does have a good local continuation at . This threatens a follow-up at b, which white might contemplate preventing with a.

Game 4, position 1

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[go]$$Wc
$$ ---------------------
$$ | . . . . . . . . . .
$$ | . X O a . . . . . .
$$ | . . X O . . . . . .
$$ | . b X O . . . . . ,
$$ | . 1 X O . . . . . .
$$ | . X O . . . . . . .
$$ | . . . . . . . . . .
$$ | . . . . . . . . . .
$$ | . . . . . . . . . .
$$ | . . . , . . . . . ,[/go]

Another 3-3 invasion joseki. After , I responded at a, which is a big mistake. I was definitely thinking about b, but I vaguely remembered seeing something like a in a professional game; however, I'm pretty sure that position was actually quite different.

Game 4, position 2

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[go]$$Bc
$$ ---------------------
$$ | . . 3 . . . . . . .
$$ | . X W 1 . . . . . .
$$ | . 2 X O . a . . . .
$$ | . 4 X O . . . . . ,
$$ | . O X O . . . . . .
$$ | . X O b . . . . . .
$$ | . 6 . . . . . . . .
$$ | . . . . . . . . . .
$$ | . . . . . . . . . .
$$ | . . . , . . . . . ,[/go]

at the marked stone. This was the sequence resulting from my first mistake. The next mistake was to play the keima at a immediately, allowing white to connect at b.

Continuation

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[go]$$Bc
$$ ---------------------
$$ | . . X . . . . . . .
$$ | . X X X . . . . . .
$$ | . O X O . 7 . . . .
$$ | . O X O . 6 . . . ,
$$ | . O X O 3 . . . . .
$$ | . X O 1 4 . . . . .
$$ | . O 2 5 . . . . . .
$$ | . . . . . . . . . .
$$ | . . . . . . . . . .
$$ | . . . , . . . . . ,[/go]

Instead, black should cut, which may result in something like the above continuation.

hakuseki wrote:Game 4, position 1

$$Wc
$$ ---------------------
$$ | . . . . . . . . . .
$$ | . X O a . . . . . .
$$ | . . X O . . . . . .
$$ | . b X O . . . . . ,
$$ | . 1 X O . . . . . .
$$ | . X O . . . . . . .
$$ | . . . . . . . . . .
$$ | . . . . . . . . . .
$$ | . . . . . . . . . .
$$ | . . . , . . . . . ,

Click Here To Show Diagram Code

[go]$$Wc
$$ ---------------------
$$ | . . . . . . . . . .
$$ | . X O a . . . . . .
$$ | . . X O . . . . . .
$$ | . b X O . . . . . ,
$$ | . 1 X O . . . . . .
$$ | . X O . . . . . . .
$$ | . . . . . . . . . .
$$ | . . . . . . . . . .
$$ | . . . . . . . . . .
$$ | . . . , . . . . . ,[/go]

Another 3-3 invasion joseki. After , I responded at a, which is a big mistake. I was definitely thinking about b, but I vaguely remembered seeing something like a in a professional game; however, I'm pretty sure that position was actually quite different.

a is a joseki as well. If KataGo says it is a mistake, it is probably based on the whole board position it is occurring in. It is not hard to construct board positions where KataGo thinks a is the best move.

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[go]$$Wc
$$ ---------------------
$$ | . . X . . . . . . .
$$ | . X X X . . . . . .
$$ | . O X O . X . . . .
$$ | . O X O . . . . . ,
$$ | . O X O . . . . . .
$$ | . X O X a W . . . .
$$ | . O O . . . . . . .
$$ | . . . . . . . . . .
$$ | . . . . . . . . . .
$$ | . . . , . . . . . ,[/go]

This is a common ending shape for this joseki. White plays instead of a when the ladder doesn't work for white. If the ladder works for white, then playing at a gives white a favorable result.

Click Here To Show Diagram Code

[go]$$Bc
$$ ---------------------
$$ | . . X . . . . . . .
$$ | . X X X . . . . . .
$$ | . O X O . . . . . .
$$ | . O X O . . . . . ,
$$ | . O X O 1 . . . . .
$$ | . X O X 2 . . . . .
$$ | . O O 3 . . . . . .
$$ | . . . . . . . . . .
$$ | . . . . . . . . . .
$$ | . . . , . . . . . ,[/go]

Black can play when the ladder favors white, white I imagine it did in your game. The results here can be more complicated. Perhaps KataGo thought this fight was also good for white in your case, which is why it wanted to play b in your original diagram.

Dusk Eagle wrote:a is a joseki as well. If KataGo says it is a mistake, it is probably based on the whole board position it is occurring in. It is not hard to construct board positions where KataGo thinks a is the best move.

Thanks for pointing this out. Yeah, after investigating some other positions it seems to be pretty situational. Maybe the ladder is a deciding factor?

BTW in the last couple weeks I've been focusing more on reviewing whole games. I will post some more openings here though at some point.

I've decided to continue this training regimen with some changes. Previously, I was playing the opening until move 30 or so. But my game analyses showed that I'm already making relatively few mistakes in that part of the game. In comparison, by move 50 I have usually made at least one huge mistake. So I will be practicing my openings until move 50.

Also, I will mix in some handicap games as well. I've found major deficiencies in my play when it comes to invading and reducing large frameworks. I think playing against a 9 stone handicap could be a helpful exercise. Studying handicap play could also help me enjoy handicap games more, which would be useful if I want to play on e.g. OGS where it's relatively hard to find an even game.

I've played some 9H games with KataGo already, which I may be posting some of later, but for the time being I'm posting about today's even game. I played black in this game. I lost 13 points by move 50.

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[go]$$Wc Responses to white 1
$$ ---------------------------------------
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . X . a . . . |
$$ | . . . O . . . . . , . . . . . 1 X . . |
$$ | . . . . . . . . . . . . . . . c b . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . , . . . . . , . . . . . , . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . , . . . . . , . . . . . O . . . |
$$ | . . X . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ ---------------------------------------[/go]

In response to white 1 I've mostly played a in the past. However, it looks like c is superior when black has the ladder. There seem to be a lot of variations for c, which may be why I've stuck with a so far. But in the future I'll try playing c if the ladder looks good for me.

In the game, I went with a:

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[go]$$Bc Joseki played in the game
$$ ---------------------------------------
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . X . 1 . . . |
$$ | . . . O . . . . . , . . . . 3 O X 5 . |
$$ | . . . . . . . . . . . . 9 7 6 4 2 . . |
$$ | . . . . . . . . . . . . . 8 . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . , . . . . . , . . . . . , . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . , . . . . . , . . . . . O . . . |
$$ | . . X . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ ---------------------------------------[/go]

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[go]$$Wc Continuation
$$ ---------------------------------------
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . X . X a . . |
$$ | . . . O . . . . . , . . . . X O X X . |
$$ | . . . . . . . . . . . 2 X X O O O 4 . |
$$ | . . . . . . . . . b 6 3 1 O . . . . . |
$$ | . . . . . . . . . 8 7 . . . . . 5 . . |
$$ | . . . . . . . . . . 9 . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . , . . . . . , . . . . . , . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . , . . . . . , . . . . . O . . . |
$$ | . . X . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ ---------------------------------------[/go]

It seems was a mistake, and white should have played at a. As black I felt like I must have also made some mistake by this point, but KataGo says everything is fine.

At this point I did feel a bit nervous about my cutting point at b, but I also thought that playing there now would be too slow, as it would give white time to erase the influence of the wall I had built.

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[go]$$Bc Black 3 should be at 'a'
$$ ---------------------------------------
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . 1 . . . . . . . X . X . . . |
$$ | . . . O . . . . . , . . . . X O X X . |
$$ | . . . . . 3 . . . . . X X X O O O X . |
$$ | . . . . . . . . . a X O O O . . . . . |
$$ | . . . . . . . . . X O . . . . . O . . |
$$ | . . . . . . . . . . O . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . , . . . . . , . . . . . , . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . 2 . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . , . . . . . , . . . . . O . . . |
$$ | . . X . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ ---------------------------------------[/go]

So I played this approach, and white played elsewhere. This would have been the perfect time to fix the weakness at a, but I played instead, which I think was slightly greedy (note, however, that is a perfectly good followup to play sometime after fixing at a).

Click Here To Show Diagram Code

[go]$$Wc White sets up a ladder breaker
$$ ---------------------------------------
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . 4 . . |
$$ | . . . . . X . . . . . . . X . X 3 . . |
$$ | . . . O . . . . . , . . . . X O X X . |
$$ | . . . . . X . . . . 6 X X X O O O X . |
$$ | . . . . . . . . . 5 X O O O . . . . . |
$$ | . . . . . . . . 8 X O . . . . . O . . |
$$ | . . . . . . . . . . O . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . , . . . . . , . . . . . , . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . O . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . a 1 7 . . . . , . . . . . O . . . |
$$ | . . X 2 . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ ---------------------------------------[/go]

White then used an approach on my 3-3 stone to set up a ladder breaker. So I captured white's stone with . But this is the biggest mistake of the game so far. It's more urgent to help my corner, for example at a.

(Game 5 to be continued)

As for the rest of game 5, I made one fundamental mistake.

Click Here To Show Diagram Code

[go]$$Bc This corner is in danger
$$ | . . . , . . . . . ,
$$ | . . . . . . . . . .
$$ | . . . . . . . . . .
$$ | . . . . . . . . . .
$$ | . . . . . . . . . .
$$ | . . . . . . . . . .
$$ | . . O O O O . . . ,
$$ | . a X X . X O . . .
$$ | . b . . . X O . . .
$$ | . . . . . . . . . .
$$ --------------------[/go]

I didn't realize how much trouble this corner is in. I think my thought process went like: "if at a, then at b, and now I'm done reading."

Click Here To Show Diagram Code

[go]$$Wc Variation: black dies
$$ | . . . , . . . . . ,
$$ | . . . . . . . . . .
$$ | . . . . . . . . . .
$$ | . . . . . . . . . .
$$ | . . . . . . . . . .
$$ | . . . . . . . . . .
$$ | . 3 O O O O . . . ,
$$ | . 1 X X . X O . . .
$$ | 4 2 . 9 6 X O . . .
$$ | . . . 5 8 7 . . . .
$$ --------------------[/go]

In the game, I ended up playing and dying. Actually black has a better option than .

Click Here To Show Diagram Code

[go]$$Bc Black can live
$$ | . . . , . . . . . ,
$$ | . . . . . . . . . .
$$ | . . . . . . . . . .
$$ | . . . . . . . . . .
$$ | . . . . . . . . . .
$$ | . . . . . . . . . .
$$ | . O O O O O . . . ,
$$ | . O X X 6 X O . . .
$$ | 3 X . 1 . X O . . .
$$ | . . 2 . 5 4 7 . . .
$$ --------------------[/go]

Actually above is not even the best move -- black would be better off sacrificing the corner to get a couple sente plays outside. But even saving part of the corner is better than my game result. Here's the rest of the sequence:

Click Here To Show Diagram Code

[go]$$Wc Conclusion -- black makes two eyes
$$ | . . . , . . . . . ,
$$ | . . . . . . . . . .
$$ | . . . . . . . . . .
$$ | . . . . . . . . . .
$$ | . . . . . . . . . .
$$ | . . . . . . . . . .
$$ | . O O O O O . . . ,
$$ | . O X X O X O . . .
$$ | X X . X 1 X O . . .
$$ | . 4 O 2 X . X 3 . .
$$ --------------------[/go]

Anyway, this is just making the best of a bad situation. This may be useful to know if I ever encounter this situation from white's point of view. But what I should have done was to defend early:

Click Here To Show Diagram Code

[go]$$Bc Black's defense
$$ | . . . , . . . . . ,
$$ | . . . . . . . . . .
$$ | . . . . . . . . . .
$$ | . . . . . . . . . .
$$ | . . . . . . . . . .
$$ | . 2 . . . . . . . .
$$ | . 1 O O O O . . . ,
$$ | . 3 X X . X O . . .
$$ | . . . . . X O . . .
$$ | . . . . . . . . . .
$$ --------------------[/go]

One final note. What was black doing while ignoring the situation in the corner?

Click Here To Show Diagram Code

[go]$$Bc A big move?
$$ ---------------------------------------
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . X . . |
$$ | . . . . . X . . . . . . . X . X O . . |
$$ | . . . O . . . . . , . . . . X O X X . |
$$ | . . . . . X . . . . X X X X O O O X . |
$$ | . . . X . . . . . O X O O O . . . . . |
$$ | . . . . . . . . X X O . . . . . O . . |
$$ | . . . . . . . . . . O . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . , . . . . . , . . . . . , . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . 1 . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . O . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . O O O O . . . , . . . . . O . . . |
$$ | . . X X . X O . . . . . . . . . . . . |
$$ | . . . . . X O . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ ---------------------------------------[/go]

Actually, there are substantially bigger moves than this. To see them, I played out (even though is too slow for white) and then observed KataGo's recommendations:

Click Here To Show Diagram Code

[go]$$Bc Some actual big moves
$$ ---------------------------------------
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . X . . |
$$ | . . d . . X . . . . . . . X . X O . . |
$$ | . . . O . . . . . , . . . . X O X X . |
$$ | . . . . . X . . . . X X X X O O O X . |
$$ | . . . X . . . . . O X O O O . . . . . |
$$ | . . . . . . . . X X O . . . . . O . . |
$$ | . . . . . . . . . . O . . . . . . . . |
$$ | . . . . . . . . a . . . . . . c . . . |
$$ | . . . , . . . . . , . . . . . , . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . e . . . . . . |
$$ | . . 4 . . . . . . . . . . . . O . . . |
$$ | . 2 . . . . . . . . . . . . . . . . . |
$$ | . 1 O O O O . . . , . . . . . O . . . |
$$ | . 3 X X . X O . . . . . . b . . . . . |
$$ | . . . . . X O . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ ---------------------------------------[/go]

I believe b is similar in spirit to the move I played. It is simply approaching the wider side instead of the narrower side. And a is playing at the boundary of the two frameworks instead of invading deep into white's framework. Perhaps one of these moves could become my first intuition.

Click Here To Show Diagram Code

[go]$$Wc 10 = a
$$ ---------------------------------------
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . 8 7 9 . . c d |
$$ | . . . . . . . . . . . . . X . 5 3 b . |
$$ | . . . O . . . . . , . . . . 4 1 X . . |
$$ | . . . . . . . . . . . . a . . 2 6 . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . , . . . . . , . . . . . , . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . , . . . . . , . . . . . O . . . |
$$ | . . X . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ ---------------------------------------[/go]

Although Black 2 at 5 or 6 are also possible, I frequently play this variation.

Black plays two excess stones but gets a wall on both sides and the ko aji B-C-D remains.

Click Here To Show Diagram Code

[go]$$Wc result
$$ ---------------------------------------
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . X O O . . . . |
$$ | . . . . . . . . . . . . . X . O O . . |
$$ | . . . O . . . . . , . . . . X O X . . |
$$ | . . . . . . . . . . . . X . . X X . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . , . . . . . , . . . . . , . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . , . . . . . , . . . . . O . . . |
$$ | . . X . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ ---------------------------------------[/go]

Thanks. I haven't seen this joseki before. In fact until recently I didn't play the large knight's enclosure much at all, so much of this is new to me.

It seems that KataGo doesn't like this joseki very much though. In your first diagram, KaTrain shows move 4 as a 3.3 point loss and move 6 as a 1 point loss.

Instead, KataGo recommends something like this:

Click Here To Show Diagram Code

[go]$$Bc Black gets territory and white is still unsettled
$$ ---------------------------------------
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . X 5 3 2 . . |
$$ | . . . O . . . . . , . . . . 4 O X 9 . |
$$ | . . . . . . . . . . . . . . . 1 8 . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . , . . . . . , . . . . . , . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . 7 6 . . . . . , . . . . . O . . . |
$$ | . . X . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ ---------------------------------------[/go]

ISTM black is making good use of the diagonal fuseki in this variation. White needs to exchange , which seems locally unfavorable, in order to threaten (not even realize) a ladder. Meanwhile black is getting solid territory in both corners.

I also looked at a parallel fuseki:

Click Here To Show Diagram Code

[go]$$Wc Still loses 2.7 points
$$ ---------------------------------------
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . X . 5 3 . . |
$$ | . . . O . . . . . , . . . . 4 1 X . . |
$$ | . . . . . . . . . . . . . . . 2 6 . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . , . . . . . , . . . . . , . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . O . . . . . , . . . . . X . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ ---------------------------------------[/go]

In this case, loses 1.6 points and loses 1.1 points. So this is about 1.6 points better than the same joseki in a diagonal fuseki context. I would guess there are two effects in play here: the absence of a ladder breaker makes cutting less valuable for black, and the 4-4 stone in the adjacent corner increases the value of black's wall a bit.

So I haven't yet seen a position where this joseki choice is actually optimal for black.

This is not the most recent game, but KataGo's advice in this game contrasts confusingly with another game I am planning to share soon, so maybe a quick discussion can help me find enlightenment.

I played black in this game. By move 50 I had made about 7 points' worth of mistakes.

Game 6, position 1

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[go]$$Bc Black should have approached at [b]a[/b] or [b]b[/b]
$$ ---------------------------------------
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . O . . . . . . . . . . . . . . . |
$$ | . . . , . . . . . , . . . . 1 , X . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . , . . . . . , . . . . . , . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . O . . . . . . . . . . . . . . . . |
$$ | . . . , . . . . . , . . . . . X . . . |
$$ | . . b a . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ ---------------------------------------[/go]

One of my goals in publishing this journal is to avoid making the same mistake twice. Yet here I have made a mistake I already discussed in game 1. The 5-3 stone is really not such a great opening, so it's important for black to approach before white can rectify the situation by making an enclosure.

Game 6, position 2

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[go]$$Bc High extension is slightly better
$$ ---------------------------------------
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . O . 6 . . . . . . . . . . . . . |
$$ | . . 4 , . . . . . , . . . . X , X . . |
$$ | . . 2 1 . . . . . . . . . . . . . . . |
$$ | . . 3 5 . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . 7 a . . . . . , . . . . . , . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . O . . . . . . . . . . . . . . . . |
$$ | . . . , . . . . . , . . . . . X . . . |
$$ | . . . O . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ ---------------------------------------[/go]

It's a small difference, but black should have played the extension on the 4th line here. I made the reverse mistake in game 1. My feeling now is that the high extension should be played in most situations, and the low extension should be used only when there is some obvious synergy with other stones nearby.

Game 6, position 3

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[go]$$Bc :b1: should be at [b]a[/b] or [b]b[/b]
$$ ---------------------------------------
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . O . O . . . . . . . . . . . . . |
$$ | . . O , . . . . . , . . . . X , X . . |
$$ | . . O X . . . . . . . . . . . . . . . |
$$ | . . X X . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . X , . . . . . , . . . . . a . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . O . . . . . . . . . . . . . . . . |
$$ | . . . , . . . . . , . . . . X X X . . |
$$ | . . . O . . . . . . . . 1 X O O O b . |
$$ | . . . . . . . . . . . . . O . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ ---------------------------------------[/go]

This position is my main reason for posting this game. It seems loses a whole point here. In a world where AI disapproves of side-oriented strategies like san-ren-sei, it's rather delightful to come across a position where the side extension is favored over a corner move.

This leads me to a hypothesis: the correct timing for a side extension is when both corners are exerting significant influence towards the side.

I may continue game 6 later, but I wanted to skip ahead to a position from game 7 that presents a confusing contrast. I played white in this game.

Click Here To Show Diagram Code

[go]$$Wc Should white play [b]a[/b], [b]b[/b], or [b]c[/b]?
$$ ---------------------------------------
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . X . . . . . . . . . . O . . . . . |
$$ | . . . , . . . . . , . . . . . O . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . , . . . . . , . . . . . c . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . X . . . . . . . . . . . . . . . |
$$ | . . . , . . . . . , . . . . O O O . . |
$$ | . . . X . . . . . . . . a O X X X b . |
$$ | . . . . . . . . . . . . . X . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ ---------------------------------------[/go]

Recalling KataGo's advice on position 3 of game 6, I chose to play c here. But KataGo says that is a bad move, and I should play a! I really don't see how a is different from the move I was admonished for playing in the previous game. I would be super happy if anyone has thoughts that can clarify this.

In the meantime perhaps my best bet is to just play b, which is at least regarded as nearly optimal in both cases.