Life In 19x19

Posted: **Thu Dec 26, 2019 3:03 pm**

Uberdude got it. The first diagram behind the cut I thought was pretty, it's not a familiar shape for me. The second diagram is best play for both sides according to KataGo.

Bill Spight wrote: Here is where Sonoda's theory of diagonal lines might have helped. :)

I can make a fair guess as to what the theory is based on your diagram, but do you want to tell us more?

Posted: **Thu Dec 26, 2019 3:18 pm**

Uberdude wrote:It's easy to connect with the standard shape of kosumi or attach against the White knight move, though there may be better moves given White's thinness and Black's support above. But I would be more concerned with reading counters (or evaluating the natural trade) to this White resistance.

$$Bc
$$ | . . . . . . . . . . . . . . . . X . . |
$$ | . . . O O O . . . . . . . . . . . . . |
$$ | . . . O X . X . . . . X . . . X . . . |
$$ | . O . . X . X . . X . . . . . . . . . |
$$ | . X O O X . . . . . . O . . . . . . . |
$$ | . X X X O O O . . O . . . . 2 X . . . |
$$ | . . . . X X O . . . . 1 . . . . . . . |
$$ | . . . X . O . . . . . . . . . . . . . |
$$ +---------------------------------------+
Click Here To Show Diagram Code
[go]$$Bc $$ | . . . . . . . . . . . . . . . . X . . | $$ | . . . O O O . . . . . . . . . . . . . | $$ | . . . O X . X . . . . X . . . X . . . | $$ | . O . . X . X . . X . . . . . . . . . | $$ | . X O O X . . . . . . O . . . . . . . | $$ | . X X X O O O . . O . . . . 2 X . . . | $$ | . . . . X X O . . . . 1 . . . . . . . | $$ | . . . X . O . . . . . . . . . . . . . | $$ +---------------------------------------+[/go]

Yes, that really does get interesting!

My first instinct is the "crude" push and cut:

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

I guess the white stones to the left are probably captured, but black gives up the lower right corner in return.

KataGo says the above diagram is not bad (third best of three moves, all within the margin of error), but its first choice move is the other push:

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

Same sort of trade, but more complex (lots of variations to explore), larger scale (black loses more of the right side but gets more compensation at the bottom).

Second choice is this striking picture:

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

Continuation:

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

and then white tenuki (and I'm not going to show you what a horrible mess I made in the top half of the board...)

Posted: **Thu Dec 26, 2019 3:41 pm**

First thing I'd consider is what if black takes the bait? Sometimes just taking the sente ponnuki can be good enough for losing the stone, and here it does solidify the 2-space shimari (which you normally don't want to attach against), and whilst I think black is not bad I think he could be even better (but more complicated so if leading big might choose this to simplify and win).

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

If white played 4 I was imagining the cleaner trade:

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

and there's also the question of what happens now? a? Looks like white is in more trouble than black.

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

maybe can even sacrifice 1 and ask if the whole thing is alive?

Click Here To Show Diagram Code: [go]$$Bcm5 $$ | . . . . . . . . . . . . . . . . X . . | $$ | . . . O O O . . . . . . . . . . . . . | $$ | . . . O X . X . . . . X . . . X . . . | $$ | . O . . X . X . . X . . . . . . . . . | $$ | . X O O X . . . . X O O . . . . . . . | $$ | . X X X O O O . . O . 4 3 1 O X . . . | $$ | . . . . X X O . . O 6 X 2 5 . . . . . | $$ | . . . X . O . . . . . . 7 . . . . . . | $$ +---------------------------------------+[/go]

Posted: **Thu Dec 26, 2019 4:10 pm**

xela wrote:Uberdude got it. The first diagram behind the cut I thought was pretty, it's not a familiar shape for me. The second diagram is best play for both sides according to KataGo.

Bill Spight wrote: Here is where Sonoda's theory of diagonal lines might have helped.
I can make a fair guess as to what the theory is based on your diagram, but do you want to tell us more?

John Fairbairn has mentioned Sonoda's ideas a few times here. For instance,

viewtopic.php?f=57&t=13724&p=212148&hil ... da#p212148

viewtopic.php?f=57&t=13724&p=212148&hil ... da#p212148

where JF says this:

Sonoda also has interesting things to say about tactics. One applicable here is that when you have more stones than your opponent you use them orthogonally and if you have fewer you use them diagonally (there is also separate advice to "cut the opponent's diagonals"). Hence the right move here for Black is N4.

I have a different Sonoda book where he talks about diagonally related plays for shinogi and sabaki. My guess is that is because diagonal relationships are more efficient for making eyes, although Sonoda does not say that.

Posted: **Thu Dec 26, 2019 6:09 pm**

Thanks Bill!

BTW, you posted the same link twice, but Googling for your quotation throws out this: viewtopic.php?f=13&t=13754

Life In 19x19

Tsumego problem from one of my recent games

Re: Tsumego problem from one of my recent games

Re: Tsumego problem from one of my recent games

Re: Tsumego problem from one of my recent games

Re: Tsumego problem from one of my recent games

Re: Tsumego problem from one of my recent games