Semeai

Bill Spight · Post by **Bill Spight** » Wed May 04, 2011 12:14 pm

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

A little test of reading skill.

Enjoy!

[admin]
Added numbers. Hope nobody minds. -JB
[/admin]

John Fairbairn · Post by **John Fairbairn** » Wed May 04, 2011 12:22 pm

The famous Go Seigen-Fujisawa catastrophe! Now that's what I call not dumbing down

HermanHiddema · Post by **HermanHiddema** » Thu May 05, 2011 2:09 am

The obvious approach seems to be :b1:

below...

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

Now black is losing the semeai

Click Here To Show Diagram Code: [go]$$Bm11 , , @ the marked points, @ $$ ---------------------- $$ | 2 O O O X X 8 O . . . $$ | B B O X X X X O X . . $$ | 1 B O O X . 6 . O O . $$ | O O O O X . O . X O . $$ | O X X O X O X . X O . $$ | X 5 X X X O . . . . . $$ | 4 X O X X O . . . . . $$ | O O O O X O . . . . . $$ | . . . . O O . . . . . $$ | . . . O . . . . . , . $$ | . . . . . . . . . . .[/go]

After white captures, he is ahead by one liberty

The alternative is to play :b1:

like this:

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

White connects under with :w2:

, then with :w4:

and

prevents black from making two eyes, allowing black to connect out, sealing him in again with :w8:

Now, unless black has some serious support on the outside, he seems dead to me.

aurik · Post by **aurik** » Thu May 05, 2011 9:21 am

HermanHiddema wrote:
The obvious approach seems to be below...
<snip>

I got

as well, but a different sequence to give black at least a ko for life. Not capturing at 6 seems to be the key.

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

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

9 @ 1, now W has 2 libs and B has 3. So W cannot play this way.

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

Click Here To Show Diagram Code: [go]$$B Seki is wishful thinking though, this reverts to ko. $$ ---------------------- $$ | O O 7 W O X . O . . . $$ | 2 1 O X X X X O X . . $$ | . 5 O O X . 3 6 O O . $$ | O O O O X 4 O . X O . $$ | O X X O X O X . X O . $$ | X . X X X O . . . . . $$ | . X O X X O . . . . . $$ | O O O O X O . . . . . $$ | . . . . O O . . . . . $$ | . . . O . . . . . , . $$ | . . . . . . . . . . .[/go]

Click Here To Show Diagram Code: [go]$$B at circled stone, B makes ko by playing atari from the outside. $$ ---------------------- $$ | O O 5 W O X . O . . . $$ | 2 1 O X X X X O X . . $$ | . 3 O O X . 4 . O O . $$ | O O O O X . O . X O . $$ | O X X O X O X . X O . $$ | X . X X X O . . . . . $$ | . X O X X O . . . . . $$ | O O O O X O . . . . . $$ | . . . . O O . . . . . $$ | . . . O . . . . . , . $$ | . . . . . . . . . . .[/go]

It feels like one should be able to exploit the weakness at h17, though. Maybe it can be used to eliminate ko entirely?

gonut · Post by **gonut** » Fri May 06, 2011 4:16 pm

One move seems to make Black miai of living and creating an extra outside liberty for the corner semeai.

Because I'm probably incorrect (such is the life of a weak kyu player), I've only included a couple sequences to show the idea.

In any event, thanks for yet another nice problem, Bill!

Post by **Joaz Banbeck** » Fri May 06, 2011 10:11 pm

aurik · Post by **aurik** » Fri May 06, 2011 11:18 pm

gonut · Post by **gonut** » Sat May 07, 2011 8:57 pm

Aurik, your refutation is correct! I missed that Black's outside stones would have a shortage of liberties. Ugh.

Anyway, I'll try once more to show what solution theme Bill probably had in mind, and then I'll go hide in a cave.

Koroviev · Post by **Koroviev** » Mon May 09, 2011 5:13 am

John Fairbairn wrote:The famous Go Seigen-Fujisawa catastrophe! Now that's what I call not dumbing down

What does this mean?

John Fairbairn · Post by **John Fairbairn** » Mon May 09, 2011 12:16 pm

What does this mean?

Even leaving metaphysics out of it, I'm not sure what you mean. Is is the reference you don't get, or is "dumbing down" too colloquial for a foreigner?

The reference is that the position comes (with a slight cosmetic change) from Game 1 of the 1951 ten-game match between Go and Fujisawa, and both players - the first 9-dans in history - famously made a mess of getting to this position. The scorekeeper pointed out they had both missed a tesuji. Even in this position, there are extreme difficulties for many amateurs involving a ko and a yoseko. Hence the presenter of this problem is not "dumbing down", i.e. is not offering something for a low level of player.

The full story is in my "9-dan Showdown".

Koroviev · Post by **Koroviev** » Mon May 09, 2011 1:56 pm

John Fairbairn wrote:
What does this mean?

Even leaving metaphysics out of it, I'm not sure what you mean. Is is the reference you don't get, or is "dumbing down" too colloquial for a foreigner?

The reference is that the position comes (with a slight cosmetic change) from Game 1 of the 1951 ten-game match between Go and Fujisawa, and both players - the first 9-dans in history - famously made a mess of getting to this position. The scorekeeper pointed out they had both missed a tesuji. Even in this position, there are extreme difficulties for many amateurs involving a ko and a yoseko. Hence the presenter of this problem is not "dumbing down", i.e. is not offering something for a low level of player.

The full story is in my "9-dan Showdown".

What I mean is: "what do you mean?" if you see what I mean. ;-)

The reference was what I was after - I'm not a foreigner by the way, just a fan of Russian literature.

Story sounds fascinating, 9-dan Showdown is now on my 'to buy' list.

emeraldemon · Post by **emeraldemon** » Thu Nov 01, 2018 8:57 am

Koroviev wrote:The reference was what I was after - I'm not a foreigner by the way, just a fan of Russian literature.

I don't know what exactly JF would consider a foreigner, but he disapproves using "cookie" for "biscuit"...

jlt · Post by **jlt** » Thu Nov 01, 2018 10:02 am

The solution to the semeai problem also appears in Abe Yoshiteru's book "Dramatic Moments On the Go Board".

Bill Spight · Post by **Bill Spight** » Thu Nov 01, 2018 12:10 pm

I had forgotten about this topic. I should have given a solution.

However, not long after posting this (Edit: in 2011) I underwent an operation for cancer, and not long after that, my wife's (then girlfriend's) brother died suddenly. Not an easy time.

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