Life In 19x19

this pattern twice in games at a tournament today.

The entire board, or just this corner ?

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[go]$$Bcm15
$$ ---------------------------------------
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . O . . . . . . . . . . . . . . . |
$$ | . . W , . . . . . , . . . . . X . . . |
$$ | . . O X . . . . . . . . . . . . . . . |
$$ | . . X O . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . , . . . . . , . . . . . , . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . X X . . . . . . . . . . . . . . . |
$$ | . . O X . . . . . . . . . . . . . . . |
$$ | . . W 3 . . . . . , . . . . . X . . . |
$$ | . . @ O 1 a . . . . . . . . . . . . . |
$$ | . . . . 2 b . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ ---------------------------------------[/go]

Basic rule of kingo: every stone attached to a group with a king should itself be a king.
Still following a pro game, but I've gotten three extra points out of our exchanges so far since I've used a few kings. I feel good about that. I expect the a / b exchange next, and possibly one more move attempting to seal me in before leaving this corner.

Just the corner with the press.

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[go]$$Bcm19
$$ ---------------------------------------
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . O . . . . . . . . . . . . . . . |
$$ | . . W , . . . . . , . . . . . X . . . |
$$ | . . O X . . . . . . . . . . . . . . . |
$$ | . . X O . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . , . . . . . , . . . . . , . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . X X . . . . . . . . . . . . . . . |
$$ | . . O X . . . . . . . . . . . . . . . |
$$ | . . W X . . . . . , . . . . . X . . . |
$$ | . . W O X 1 . 3 . . . . . . . . . . . |
$$ | . . . . O 2 . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ ---------------------------------------[/go]

The trigger still applies if :W20: is a king.

This is what I expected. I assume white will move in the upper left next.

jeromie wrote: ...
I assume white will move in the upper left next.

C13 is huge.

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[go]$$Bcm19
$$ ---------------------------------------
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . O . . . . . . . . . . . . . . . |
$$ | . . W , . . . . . , . . . . . X . . . |
$$ | . . O X . . . . . . . . . . . . . . . |
$$ | . . X O . . . . . . . . . . . . . . . |
$$ | . . O . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . , . . . . . , . . . . . , . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . X X . . . . . . . . . . . . . . . |
$$ | . . O X . . . . . . . . . . . . . . . |
$$ | . . W X . . . . . , . . . . . X . . . |
$$ | . . W O X 1 . 3 . . . . . . . . . . . |
$$ | . . . . O @ . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ ---------------------------------------[/go]

Click Here To Show Diagram Code

[go]$$Bcm19
$$ ---------------------------------------
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . O . . . . . . . . . . . . . . . |
$$ | . . W , . . . . . , . . . . . X . . . |
$$ | . . O X . . . . . . . . . . . . . . . |
$$ | . . X O . . . . . . . . . . . . . . . |
$$ | . . b . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . , . . . . . , . . . . . T . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . X X . . . . . . . . . . . . . . . |
$$ | . . O X . . . . . . . . . . . . . . . |
$$ | . . W X . . . . . , . . . . . X . . . |
$$ | . . W O X 1 a 3 . . . . . . . . . . . |
$$ | . . . . O @ . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ ---------------------------------------[/go]

There are two moves that have been played in this position by professional players, a and b. a occurred in a game by Cho Chikun, and he came back to b after the exchange. I don't think I can take advantage of that exchange if black were to tenuki, so I'm going to make the other move and play b directly. I expect black will play at the triangled point to make a sanrensai next.

Once again, there is the question of whether I should make my move a king. I could imagine some situation where black could use the threat of capturing a king to get some outside influence, but truthfully I think it breaks my strategy for that corner if I were to let that black stone escape. So I'm making it a king, trusting that the small gains in efficiency I am making will offset the heaviness of my stones later.

The left and the bottom seem like obvious places not to play right now, which leaves the top or the right hand side.

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[go]$$Bcm23
$$ ---------------------------------------
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . 8 . . . . . |
$$ | . . . O . . . . . . . 3 . 2 . 6 4 . . |
$$ | . . W , . . . . . , . . . . 7 X 5 . . |
$$ | . . O X . . . . . . . . 9 . . . . . . |
$$ | . . X O . . . . . . . . . . . . . . . |
$$ | . . @ . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . , . . . . . , . . . . . 1 . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . X X . . . . . . . . . . . . . . . |
$$ | . . O X . . . . . . . . . . . . . . . |
$$ | . . W X . . . . . , . . . . . X . . . |
$$ | . . W O X X . X . . . . . . . . . . . |
$$ | . . . . O O . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ ---------------------------------------[/go]

Click Here To Show Diagram Code

[go]$$Bcm23
$$ ---------------------------------------
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . O . . . . . . . . 1 . . . . . . |
$$ | . . W , . . . . . , . . . . . X B . . |
$$ | . . O X . . . . . . . . . . . . . . . |
$$ | . . X O . . . . . . . . . . . . 2 . . |
$$ | . . @ . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . 4 . . |
$$ | . . . , . . . . . , . . . . . , . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . X X . . . . . . . . . . . . . . . |
$$ | . . O X . . . . . . . . . . . . . . . |
$$ | . . W X . . . . . , . . . . . X . . . |
$$ | . . W O X X . X . . . . . . . . . . . |
$$ | . . . . O O . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ ---------------------------------------[/go]

I don't know how I'd continue here.

Click Here To Show Diagram Code

[go]$$Bcm23
$$ ---------------------------------------
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . O . . . . . . 8 . 1 . . . . . . |
$$ | . . W , . . . . . , . . . . . X . 9 . |
$$ | . . O X . . . . . . . . . . . . . . . |
$$ | . . X O . . . . . . . . . . 4 . 2 . . |
$$ | . . @ . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . 6 . 3 . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . , . . . . . , . . . . . , . . . |
$$ | . . . . . . . . . . . . . . 7 . 5 . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . X X . . . . . . . . . . . . . . . |
$$ | . . O X . . . . . . . . . . . . . . . |
$$ | . . W X . . . . . , . . . . . X . . . |
$$ | . . W O X X . X . . . . . . . . . . . |
$$ | . . . . O O . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ ---------------------------------------[/go]

The two stones in the lower right are nice to have, and White is not fully settled, but the top is also nice for W.

All told, I'm leaning towards the sanrensei, if only because I feel like I understand the position more.

A further question is how to evaluate the influence vs territory trade that we've made so far, relative to an ordinary game of go. Say in normal go, the expected score in this position is +/- X. How does the expected score in this game compare? There are 5 white kings already played, which is one component. There is whatever loss of flexibility white has from those kings, which I think is small on this board. Then there's the value of Black's moyo. Is it larger than it would be in regular go, or can White claim those 5 points as pure profit? It's hard to tell, but I think this position is probably better for White than the corresponding position in regular go. Hopefully I'm wrong about that.

I'm surprised how few kings they play. Many of these corner stones are already close to 100% alive in the lower left.

I'm eager to deviate from the (single) professional game we are still following, but every resource I've looked at regarding playing against the sanrensai has this approach as the most common move. Of course the fact that the left side corners are mostly finished changes the game, but if black plays passively I can threaten to build a large moyo on the top. I'm expecting a pincer, but I'll probably deviate from the pro game soon after that. I'm not sure I like the way white handled his group, and I'm still thinking about a 3-3 invasion. I've got to be careful about that, though - there could be a deviation from normal joseki that would capture some stones at the expense of an awful outside result that would lead to an instant win if I play a king at the wrong time. (See for example https://senseis.xmp.net/?NineteenPointTrickPlay. In this case the invader makes the decision to sacrifice, but I'm not sure there aren't similar lines that would capture a 3-3 stone for a global loss that would lead to an instant win if I play a king.)