Life In 19x19

Posted: **Sun Nov 17, 2013 11:12 pm**

Here is a nice under the stones problem from Common Sense in Go (碁の常識) by Kubomatsu.

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

The four stone square of Black stones is a dead giveaway that this is an under the stones problem.

But there are a couple of niceties.

Enjoy!

Posted: **Sun Nov 17, 2013 11:40 pm**

I'm thinking this.

Obviously black can't play like this...

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

Nor can black do this.

Click Here To Show Diagram Code: [go]$$Wc Black is still dead by bent 4. $$ ---------------- $$ . . . O X X C O | $$ . . . O X X 2 O | $$ . . . O . O X O | $$ . . O . , O X . | $$ . . . . . O X 4 | $$ . . . . . O X 3 | $$ . . . . . O X 1 | $$ . . . . . O X O | $$ . . . . . . O 5 | $$ . . . . , . O . | $$ . . . . . . . . | $$ . . . . . . . . |[/go]

Or this.

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

But if black takes the stones white cannot capture the 4...

Click Here To Show Diagram Code: [go]$$Wc Self-atari $$ ---------------- $$ . . . O C C 7 O | $$ . . . O C 8 3 O | $$ . . . O 5 O X O | $$ . . O . , O X 6 | $$ . . . . . O X . | $$ . . . . . O X 2 | $$ . . . . . O X C | $$ . . . . . O X C | $$ . . . . . . O 4 | $$ . . . . , . O . | $$ . . . . . . . . | $$ . . . . . . . . |[/go]

So, how does white kill then?

Like this:

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

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

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

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

There is only 1 sequence I can't figure out...

Click Here To Show Diagram Code: [go]$$Wc $$ ---------------- $$ . . . O C 9 7 O | $$ . . . O C 8 3 O | $$ . . . O 5 O X O | $$ . . O . , O X 6 | $$ . . . . . O X . | $$ . . . . . O X 1 | $$ . . . . . O X 2 | $$ . . . . . O X C | $$ . . . . . . O 4 | $$ . . . . , . O . | $$ . . . . . . . . | $$ . . . . . . . . |[/go]

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

Click Here To Show Diagram Code: [go]$$Bc Favorable ko for white $$ ---------------- $$ . . . O C 4 X 1 | $$ . . . O O X 2 3 | $$ . . . O O O X X | $$ . . O . , O X X | $$ . . . . . O X . | $$ . . . . . O X O | $$ . . . . . O X X | $$ . . . . . O X . | $$ . . . . . . O X | $$ . . . . , . O . | $$ . . . . . . . . | $$ . . . . . . . . |[/go]

Is this the best white can do?

Under the stones, anyone?