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http://www.lifein19x19.com/viewtopic.php?f=15&t=1599
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Author:  willemien [ Thu Sep 09, 2010 6:16 am ]
Post subject:  status

Hello i stubled on this position that i christianed as a Stair ten in the corner


Click Here To Show Diagram Code
[go]$$B
$$ --------------
$$ | . . . . X O .
$$ | . a . X X O .
$$ | . . X X O . .
$$ | . X X O . O .
$$ | X X O . . . .
$$ | O O . O . . .
$$ | . . . . . . .[/go]


I think that White can get a seki or a ko

But is there a way for Black to keep his territory?

PS this is in preperation for a page on sensei's library on this corner shape

Author:  Joaz Banbeck [ Thu Sep 09, 2010 7:19 am ]
Post subject:  Re: status

I don't think that there is much long term benefit to doing this ( sorry! ), for arriving at the position almost certainly requires some serious DDK mistakes.

If the position gets to this point, such that black is getting locked in and running out of external liberties, 'a' is the natural play before 'b' or 'c'.

Click Here To Show Diagram Code
[go]$$B
$$ --------------
$$ | . . . . b O .
$$ | . a . X X O .
$$ | . . X X O . .
$$ | . X X O . O .
$$ | c X O . . . .
$$ | O O . O . . .
$$ | . . . . . . .[/go]

Author:  HermanHiddema [ Thu Sep 09, 2010 7:28 am ]
Post subject:  Re: status

willemien wrote:
Hello i stubled on this position that i christianed as a Stair ten in the corner


Click Here To Show Diagram Code
[go]$$B
$$ --------------
$$ | . . . . X O .
$$ | . a . X X O .
$$ | . . X X O . .
$$ | . X X O . O .
$$ | X X O . . . .
$$ | O O . O . . .
$$ | . . . . . . .[/go]


I think that White can get a seki or a ko

But is there a way for Black to keep his territory?

PS this is in preperation for a page on sensei's library on this corner shape


White can get nothing here, it's just black territory.

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


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


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


All other variations revert to one of these.

Author:  Joaz Banbeck [ Thu Sep 09, 2010 7:54 am ]
Post subject:  Re: status

Click Here To Show Diagram Code
[go]$$W
$$ --------------
$$ | . . 2 . X O .
$$ | . 1 . X X O .
$$ | 3 . X X O . .
$$ | . X X O . O .
$$ | X X O . . . .
$$ | O O . O . . .
$$ | . . . . . . .[/go]

Author:  freegame [ Thu Sep 09, 2010 8:01 am ]
Post subject:  Re: status

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


looks a lot like seki to me.
black can also start a ko with :b6: & :w7: , but this is a very bad ko for black.

Author:  Joaz Banbeck [ Thu Sep 09, 2010 8:12 am ]
Post subject:  Re: status

Or a seki like this:

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

Author:  tapir [ Thu Sep 09, 2010 9:45 am ]
Post subject:  Re: status

willemien wrote:
Hello i stubled on this position that i christianed as a Stair ten in the corner


Click Here To Show Diagram Code
[go]$$B
$$ --------------
$$ | . . . . X O .
$$ | . a . X X O .
$$ | . . X X O . .
$$ | . X X O . O .
$$ | X X O . . . .
$$ | O O . O . . .
$$ | . . . . . . .[/go]


I think that White can get a seki or a ko

But is there a way for Black to keep his territory?

PS this is in preperation for a page on sensei's library on this corner shape


I would make problems out of this, it is such a special and unlikely shape to put to the corner shapes. And is it really a staircase, it looks suspiciously like a absent big b2 bomber to my eye ;-)

Author:  HermanHiddema [ Thu Sep 09, 2010 10:11 am ]
Post subject:  Re: status

Heh, sorry, seems I posted to hastily. Seki indeed :)

I agree with tapir that it's not really suitable for corner shapes though, it is too uncommon and will just clutter the page, better as a tsumego.

Author:  Joaz Banbeck [ Thu Sep 09, 2010 2:59 pm ]
Post subject:  Re: status

HermanHiddema wrote:
Heh, sorry, seems I posted to hastily...


A few more oversights and you'll be down to my level of accuracy. :)

Author:  willemien [ Thu Sep 09, 2010 3:02 pm ]
Post subject:  Re: status

thanks for all the answers. :bow:

I think it is a good shape for the Corner shapes page.

I always intended that page as a collection of different corner shapes that are just not territory. :grumpy:

and this is a rather simple ahape ( no cutting points or so)
and also it is one of the biggest shapes that is still not territory.

(or are there 11 point empty spaces without cutting points that can be turned into seki or ko?)

Another problem that is still bothering me what is the status of the [sl=]FiveStonesOnTheThirdLineInTheCorner[/sl]

Click Here To Show Diagram Code
[go]$$B status?
$$+-------------------
$$|. . . . . . . . .
$$|. . . . . . . . .
$$|O O O O O X . . .
$$|X X X X X X . . .
$$|. . . . . . . . .[/go]

Author:  Solomon [ Thu Sep 09, 2010 9:23 pm ]
Post subject:  Re: status

willemien wrote:
Another problem that is still bothering me what is the status of the [sl=]FiveStonesOnTheThirdLineInTheCorner[/sl]

Click Here To Show Diagram Code
[go]$$B status?
$$+-------------------
$$|. . . . . . . . .
$$|. . . . . . . . .
$$|O O O O O X . . .
$$|X X X X X X . . .
$$|. . . . . . . . .[/go]

Depends who goes first.

Author:  Joaz Banbeck [ Thu Sep 09, 2010 9:45 pm ]
Post subject:  Re: status

Black can prevent easy life if he plays first:

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


White can choose a ko:

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


..or a seki:

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



The ko is expensive for white and cheap for black. Also, white must win it several times. So white almost certainly prefers the seki.

Author:  Dusk Eagle [ Thu Sep 09, 2010 9:50 pm ]
Post subject:  Re: status

Joaz Banbeck wrote:
Black can prevent easy life if he plays first.

I don't think so:

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

Author:  Joaz Banbeck [ Thu Sep 09, 2010 10:14 pm ]
Post subject:  Re: status

:oops:
Seems I posted hastily too...

Author:  Solomon [ Thu Sep 09, 2010 11:30 pm ]
Post subject:  Re: status

Joaz Banbeck wrote:
:oops:
Seems I posted hastily too...

Who is the other person who posted hastily? If it was me, rest assured I didn't and still stand by what I said as I was not thinking of :b1: in your figures:

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

I am fairly certain that if it's Black to play and he plays first here, there is no way for White to live unconditionally. I would be delighted to see a refutation though as I couldn't find any after quite some thought. Instead of posting 8,318 different variations that seem to work, I'll just wait for variations from others that show White can live unconditionally and try to debunk those.

Author:  Joaz Banbeck [ Thu Sep 09, 2010 11:57 pm ]
Post subject:  Re: status

Araban wrote:
Joaz Banbeck wrote:
:oops:
Seems I posted hastily too...

Who is the other person who posted hastily? ...


I was actually referring to Herman ( see post #8 above )

However, now that you mention it, you too get to join our illustrious group. :D Segoe Kensaku 8P, in "Go Proverbs Illustrated", which was first printed in 1960, says that it is alive.

Author:  Solomon [ Fri Sep 10, 2010 12:02 am ]
Post subject:  Re: status

Joaz Banbeck wrote:
However, now that you mention it, you too get to join our illustrious group. :D Segoe Kensaku 8P, in "Go Proverbs Illustrated", which was first printed in 1960, says that it is alive.

Did he, per chance, post the variation along with it? I can't be satisfied until I see it for myself.

Author:  Joaz Banbeck [ Fri Sep 10, 2010 12:43 am ]
Post subject:  Re: status

Araban wrote:
Joaz Banbeck wrote:
However, now that you mention it, you too get to join our illustrious group. :D Segoe Kensaku 8P, in "Go Proverbs Illustrated", which was first printed in 1960, says that it is alive.

Did he, per chance, post the variation along with it? I can't be satisfied until I see it for myself.


It is past midnight here. I'll dig up my copy tomorrow.

BTW, welcome back to the world of go players.

Author:  tj86430 [ Fri Sep 10, 2010 1:12 am ]
Post subject:  Re: status

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

I am fairly certain that if it's Black to play and he plays first here, there is no way for White to live unconditionally. I would be delighted to see a refutation though as I couldn't find any after quite some thought. Instead of posting 8,318 different variations that seem to work, I'll just wait for variations from others that show White can live unconditionally and try to debunk those.

What happens after

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


(I'm not saying white lives, but I want to learn how black kills)

Author:  Solomon [ Fri Sep 10, 2010 1:22 am ]
Post subject:  Re: status

tj86430 wrote:
Araban wrote:
Click Here To Show Diagram Code
[go]$$Bc
$$+-------------------
$$|. 1 . . . . . . .
$$|. . . . . . . . .
$$|O O O O O X . . .
$$|X X X X X X . . .
$$|. . . . . . . . .[/go]

I am fairly certain that if it's Black to play and he plays first here, there is no way for White to live unconditionally. I would be delighted to see a refutation though as I couldn't find any after quite some thought. Instead of posting 8,318 different variations that seem to work, I'll just wait for variations from others that show White can live unconditionally and try to debunk those.

What happens after

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


(I'm not saying white lives, but I want to learn how black kills)

I never claimed Black kills, simply that White cannot live unconditionally. Thus, seki and (desperate) kos count. The continuation I had in mind was:

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

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