life & death from a pro game

macelee · #1

From today's Chinese League A: http://www.go4go.net/go/games/sgfview/49888

How would black survive if white playes 'a' now? It took me quite a while to find out.

Click Here To Show Diagram Code: [go]$$Bm $$ +---------------------------------------+ $$ | . . O O . . . . . . . . . . . . . . . | $$ | X O O X O . X . . . . . . . . . . . . | $$ | . X X X O X . X . . . . . X . X X O . | $$ | . X O O . O X . X , . X . . . X O . . | $$ | . X X O . O O . . X . O X X . . . O . | $$ | X O O O . X O . O O O . O O O . O . . | $$ | . X X X . X X O . . . . . . . . . . . | $$ | 1 . a . O X . X . . . O . . . . . . . | $$ | X X . X X . X . O . X X X . . . . . . | $$ | . O O , . O . . O O O X X . . , . . . | $$ | . . O O O . X . O X X . . X . . O . . | $$ | . X O X X O . . . . O X X O O O . . . | $$ | . O X O . . . . . . . . X X X . . . . | $$ | . X X . . . . . O . X . X O . . O . . | $$ | . . . . . . O O . O X O . . O . . . . | $$ | . X . O . . . . O X O . X X X O X . . | $$ | . . X . . O . X O X X . . O X O O O . | $$ | . . . . . . . . X O X . . . . X X . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ +---------------------------------------+[/go]

jdl · #2

This is as close as I can come to something that looks like it might work. If white plays 7 black can play 6.

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

DrStraw · #3

How about this?

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

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

Click Here To Show Diagram Code: [go]$$Wm $$ +---------------------------------------+ $$ | . . O O . . . . . . . . . . . . . . . | $$ | X O O X O . X . . . . . . . . . . . . | $$ | . X X X O X . X . . . . . X . X X O . | $$ | . X O O . O X . X , . X . . . X O . . | $$ | . X X O . O O . . X . O X X . . . O . | $$ | X O O O . X O O O O O . O O O . O . . | $$ | . X X X . X X O X . . . . . . . . . . | $$ | X . O . O X . X X O . O . . . . . . . | $$ | X X . X X O X X O 0 X X X . . . . . . | $$ | . O O , . O . . O O O X X . . , . . . | $$ | . . O O O 1 X X O X X 4 . X . . O . . | $$ | . X O X X O 9 5 2 3 O X X O O O . . . | $$ | . O X O . . . 8 6 7 . . X X X . . . . | $$ | . X X . . . . . O . X . X O . . O . . | $$ | . . . . . . O O . O X O . . O . . . . | $$ | . X . O . . . . O X O . X X X O X . . | $$ | . . X . . O . X O X X . . O X O O O . | $$ | . . . . . . . . X O X . . . . X X . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ +---------------------------------------+[/go]

Click Here To Show Diagram Code: [go]$$Wm $$ +---------------------------------------+ $$ | . . O O . . . . . . . . . . . . . . . | $$ | X O O X O . X . . . . . . . . . . . . | $$ | . X X X O X . X . . . . . X . X X O . | $$ | . X O O . O X . X , . X . . . X O . . | $$ | . X X O . O O . . X . O X X . . . O . | $$ | X O O O . X O O O O O . O O O . O . . | $$ | . X X X . X X O X . . . . . . . . . . | $$ | X . O . O X . X X O . O . . . . . . . | $$ | X X . X X O X X O . X X X . . . . . . | $$ | . O O , . O . . O O O X X . . , . . . | $$ | . . O O O 1 X X O X X 5 . X . . O . . | $$ | . X O X X O 8 . 2 3 O X X O O O . . . | $$ | . O X O . 0 6 9 4 7 . . X X X . . . . | $$ | . X X . . . . . O . X . X O . . O . . | $$ | . . . . a . O O . O X O . . O . . . . | $$ | . X . O . . . . O X O . X X X O X . . | $$ | . . X . . O . X O X X . . O X O O O . | $$ | . . . . . . . . X O X . . . . X X . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ +---------------------------------------+[/go]

Where does this last one lead to? After W captures, B plays a

Fedya · #4

Just a guess, but it involves the aji of the cut at E9?

Edit: The intervening posts that came in while I was trying to figure this out show me just how woeful my reading skills are. :oops:

ez4u · #5

I am thinking something like below.

Click Here To Show Diagram Code: [go]$$Wc $$ --------------------------------------- $$ | . . O O . . . . . . . . . . . . . . . | $$ | X O O X O . X . . . . . . . . . . . . | $$ | . X X X O X . X . . . . . X . X X O . | $$ | . X O O . O X . X , . X . . . X O . . | $$ | . X X O . O O . . X . O X X . . . O . | $$ | X O O O 3 X O . O O O . O O O . O . . | $$ | . X X X 4 X X O . . . . . . . . . . . | $$ | X . 1 5 O X . X 8 9 . O . . . . . . . | $$ | X X 2 X X 7 X 6 O . X X X . . . . . . | $$ | . O O , . O . . O O O X X . . , . . . | $$ | . . O O O 0 X . O X X . . X . . O . . | $$ | . X O X X O . . . . O X X O O O . . . | $$ | . O X O . . . . . . . . X X X . . . . | $$ | . X X . . . . . O . X . X O . . O . . | $$ | . . . . . . O O . O X O . . O . . . . | $$ | . X . O . . . . O X O . X X X O X . . | $$ | . . X . . O . X O X X . . O X O O O . | $$ | . . . . . . . . X O X . . . . X X . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ ---------------------------------------[/go]

White is short of liberties and can't prevent Black from connecting under on the left side. If she tries...

Click Here To Show Diagram Code: [go]$$Wc $$ --------------------------------------- $$ | . . O O . . . . . . . . . . . . . . . | $$ | X O O X O . X . . . . . . . . . . . . | $$ | . X X X O X . X . . . . . X . X X O . | $$ | . X O O . O X . X , . X . . . X O . . | $$ | . X X O . O O . . X . O X X . . . O . | $$ | X O O O O X O . O O O . O O O . O . . | $$ | . X X X X X X O . . . . . . . . . . . | $$ | X . O O O X . X X O . O . . . . . . . | $$ | X X X X X O X X O . X X X . . . . . . | $$ | 2 O O , 1 O . . O O O X X . . , . . . | $$ | 3 5 O O O X X 8 O X X . . X . . O . . | $$ | 4 X O X X O . . . . O X X O O O . . . | $$ | 7 O X O 6 0 . . . . . . X X X . . . . | $$ | . X X 9 . . . . O . X . X O . . O . . | $$ | . . . . . . O O . O X O . . O . . . . | $$ | . X . O . . . . O X O . X X X O X . . | $$ | . . X . . O . X O X X . . O X O O O . | $$ | . . . . . . . . X O X . . . . X X . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ ---------------------------------------[/go]

Darrell · #6

DrStraw wrote:

How about this?

DrStraw wrote:

Click Here To Show Diagram Code: [go]$$Wm $$ +---------------------------------------+ $$ | . . O O . . . . . . . . . . . . . . . | $$ | X O O X O . X . . . . . . . . . . . . | $$ | . X X X O X . X . . . . . X . X X O . | $$ | . X O O . O X . X , . X . . . X O . . | $$ | . X X O . O O . . X . O X X . . . O . | $$ | X O O O . X O O O O O . O O O . O . . | $$ | . X X X . X X O X . . . . . . . . . . | $$ | X . O . O X . X X O . O . . . . . . . | $$ | X X . X X O X X O . X X X . . . . . . | $$ | . O O , . O . . O O O X X . . , . . . | $$ | . . O O O 1 X X O X X 5 . X . . O . . | $$ | . X O X X O 8 . 2 3 O X X O O O . . . | $$ | . O X O . 0 6 9 4 7 . . X X X . . . . | $$ | . X X . . . . . O . X . X O . . O . . | $$ | . . . . a . O O . O X O . . O . . . . | $$ | . X . O . . . . O X O . X X X O X . . | $$ | . . X . . O . X O X X . . O X O O O . | $$ | . . . . . . . . X O X . . . . X X . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ +---------------------------------------+[/go]

Where does this last one lead to? After W captures, B plays a

This does not work because W would capture with 1 then gets to play a first

Click Here To Show Diagram Code: [go]$$Wm $$ +---------------------------------------+ $$ | . . O O . . . . . . . . . . . . . . . | $$ | X O O X O . X . . . . . . . . . . . . | $$ | . X X X O X . X . . . . . X . X X O . | $$ | . X O O . O X . X , . X . . . X O . . | $$ | . X X O . O O . . X . O X X . . . O . | $$ | X O O O . X O O O O O . O O O . O . . | $$ | . X X X . X X O X . . . . . . . . . . | $$ | X . O . O X . X X O . O . . . . . . . | $$ | X X . X X O X X O . X X X . . . . . . | $$ | . O O , . O . . O O O X X . . , . . . | $$ | . . O O O . X X O X X 5 . X . . O . . | $$ | . X O X X O 8 . 2 3 O X X O O O . . . | $$ | . O X O 1 0 6 9 4 7 . . X X X . . . . | $$ | . X X . . . . . O . X . X O . . O . . | $$ | . . . . a . O O . O X O . . O . . . . | $$ | . X . O . . . . O X O . X X X O X . . | $$ | . . X . . O . X O X X . . O X O O O . | $$ | . . . . . . . . X O X . . . . X X . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ +---------------------------------------+[/go]

Kirby · #7

Click Here To Show Diagram Code: [go]$$Bm $$ +---------------------------------------+ $$ | . . O O . . . . . . . . . . . . . . . | $$ | X O O X O . X . . . . . . . . . . . . | $$ | . X X X O X . X . . . . . X . X X O . | $$ | . X O O . O X . X , . X . . . X O . . | $$ | . X X O . O O . . X . O X X . . . O . | $$ | X O O O . X O . O O O . O O O . O . . | $$ | . X X X . X X O . . . . . . . . . . . | $$ | X . W 2 O X . X 5 6 . O . . . . . . . | $$ | X X 1 X X 4 X 3 O . X X X . . . . . . | $$ | . O O , 0 O . . O O O X X . . , . . . | $$ | . . O O O 9 X 7 O X X . . X . . O . . | $$ | . X O X X O . . 8 . O X X O O O . . . | $$ | . O X O . . . . . . . . X X X . . . . | $$ | . X X . . . . . O . X . X O . . O . . | $$ | . . . . . . O O . O X O . . O . . . . | $$ | . X . O . . . . O X O . X X X O X . . | $$ | . . X . . O . X O X X . . O X O O O . | $$ | . . . . . . . . X O X . . . . X X . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ +---------------------------------------+[/go]

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

OR

Click Here To Show Diagram Code: [go]$$Bm $$ +---------------------------------------+ $$ | . . O O . . . . . . . . . . . . . . . | $$ | X O O X O . X . . . . . . . . . . . . | $$ | . X X X O X . X . . . . . X . X X O . | $$ | . X O O . O X . X , . X . . . X O . . | $$ | . X X O . O O . . X . O X X . . . O . | $$ | X O O O . X O . O O O . O O O . O . . | $$ | . X X X . X X O . . . . . . . . . . . | $$ | X . W 2 O X . X 5 6 . O . . . . . . . | $$ | X X 1 X X 4 X 3 O . X X X . . . . . . | $$ | . O O , 0 O . . O O O X X . . , . . . | $$ | . . O O O 9 X 7 O X X . . X . . O . . | $$ | . X O X X O . 8 . . O X X O O O . . . | $$ | . O X O . . . . . . . . X X X . . . . | $$ | . X X . . . . . O . X . X O . . O . . | $$ | . . . . . . O O . O X O . . O . . . . | $$ | . X . O . . . . O X O . X X X O X . . | $$ | . . X . . O . X O X X . . O X O O O . | $$ | . . . . . . . . X O X . . . . X X . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ +---------------------------------------+[/go]

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

macelee · #8

So many attempts! Good to see you are actually interested in this sort of post. Let's first simplify the problem.

Following is taken from ez4u's answer, which is the correct sequence if white attempts to kill this group.

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

Now the problem becomes:

Click Here To Show Diagram Code: [go]$$Bmc black to survive $$ +---------------------------------------+ $$ | . . O O . . . . . . . . . . . . . . . | $$ | X O O X O . X . . . . . . . . . . . . | $$ | . X X X O X . X . . . . . X . X X O . | $$ | . X O O . O X . X , . X . . . X O . . | $$ | . X X O . O O . . X . O X X . . . O . | $$ | X O O O O X O . O O O . O O O . O . . | $$ | . X X X X X X O . . . . . . . . . . . | $$ | X . O O O X . X . . . O . . . . . . . | $$ | X X X X X b X a O . X X X . . . . . . | $$ | . O O , . O c . O O O X X . . , . . . | $$ | . . O O O . X . O X X . . X . . O . . | $$ | . X O X X O . . . . O X X O O O . . . | $$ | . @ X O . . . . . . . . X X X . . . . | $$ | . X X . . . . . O . X . X O . . O . . | $$ | . . . . . . O O . O X O . . O . . . . | $$ | . X . O . . . . O X O . X X X O X . . | $$ | . . X . . O . X O X X . . O X O O O . | $$ | . . . . . . . . X O X . . . . X X . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ +---------------------------------------+[/go]

Next black most certainly would play 'a' instead of 'b'. If swapping these two, white would have another way home at 'c' so black is hopeless. So what's next? Note that the aji of the marked stone must be exploited.

Kirby · #9

I see. My move 7 wasn't sente. I don't know why I misread that it was.

Anyway, macelee, you're right: these types of posts are interesting, and I'd be happy to see more of them in the future.

macelee · **#10**

Kirby wrote:

I see. My move 7 wasn't sente. I don't know why I misread that it was.

Anyway, macelee, you're right: these types of posts are interesting, and I'd be happy to see more of them in the future.

Well done. Indeed :b7:

in Kirby's original answer did not work, as show below:

macelee · **#11**

Now the solution:

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

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

If whites plays :w1:

cut,

cannot be saved because of short of liberty. Note in the previous diagram, :w8:

can separate at 'a' too, but that does not affect the end result.

ez4u · **#12**

macelee wrote: