It is currently Thu Mar 28, 2024 1:32 pm

All times are UTC - 8 hours [ DST ]




Post new topic Reply to topic  [ 3 posts ] 
Author Message
Offline
 Post subject: How superko can change a losing position into a winning one
Post #1 Posted: Tue Sep 01, 2020 1:30 pm 
Lives in sente

Posts: 1236
Liked others: 21
Was liked: 57
Rank: 1d
Black to play and win
Click Here To Show Diagram Code
[go]$$B
$$ -----------
$$ | O . a . O -
$$ | O O O O O -
$$ | O O O O O -
$$ | O O O O O -
$$ | O O O O O -
$$ -----------[/go]


I suppose we are using AGA rule (SSK) on a 5x5 board.

The problem I propose is the following:

Starting with an empty board, what is the minimum number of moves you need to build the above position such that black can play and win.

Note : if for example you play 44 moves (22 pass for black + 22 white stones played by white) then the above position is a losing one for black because after a black move on "a" the position looks like a strange seki with only one black stone involved! Is this is true then it is a large win for white.

You have to find something else and minimise the number of moves!

Top
 Profile  
 
Offline
 Post subject: Re: How superko can change a losing position into a winning
Post #2 Posted: Tue Sep 01, 2020 3:43 pm 
Lives in sente
User avatar

Posts: 914
Liked others: 391
Was liked: 162
Rank: German 2 dan
Why would that be a seki?

_________________
A good system naturally covers all corner cases without further effort.

Top
 Profile  
 
Offline
 Post subject: Re: How superko can change a losing position into a winning
Post #3 Posted: Wed Sep 02, 2020 1:48 am 
Lives in sente

Posts: 1236
Liked others: 21
Was liked: 57
Rank: 1d
Harleqin wrote:
Why would that be a seki?


The point is the following: after the sequence

Click Here To Show Diagram Code
[go]$$B
$$ -----------
$$ | O 3 1 4 O -
$$ | O O O O O -
$$ | O O O O O -
$$ | O O O O O -
$$ | O O O O O -
$$ -----------[/go]

:w2: pass
:b5: on :b1:
:w6: on :b3:
:b7: on :b1:

it follows

Click Here To Show Diagram Code
[go]$$Wm8
$$ -----------
$$ | . . X . . -
$$ | . . . . . -
$$ | . . 1 . . -
$$ | . . . . . -
$$ | . . . . . -
$$ -----------[/go]


and here my impression is that black cannot live somewhere on the board. Maybe I am not strong enough to show this and I hope stronger player will be able to confirm my impression.

If it is true the position is seki because after

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


we reach the position

Click Here To Show Diagram Code
[go]$$Wm4
$$ -----------
$$ | . . X X . -
$$ | . . . . . -
$$ | . . 1 . . -
$$ | . . . . . -
$$ | . . . . . -
$$ -----------[/go]


and now it appears to me that black can live with a better result than the initial position after black 1

Top
 Profile  
 
Display posts from previous:  Sort by  
Post new topic Reply to topic  [ 3 posts ] 

All times are UTC - 8 hours [ DST ]


Who is online

Users browsing this forum: No registered users and 1 guest


You cannot post new topics in this forum
You cannot reply to topics in this forum
You cannot edit your posts in this forum
You cannot delete your posts in this forum
You cannot post attachments in this forum

Search for:
Jump to:  
Powered by phpBB © 2000, 2002, 2005, 2007 phpBB Group