Re: Interesting go problem from Daiki Komatsu twitter
Posted: Wed Nov 02, 2016 12:47 pm
by Kirby
Nice problem... One of the comments seems to suggest 7, but I don't see it, yet.
Re: Interesting go problem from Daiki Komatsu twitter
Posted: Wed Nov 02, 2016 1:35 pm
by HermanHiddema
Copyable diagram, for those who want to post an attempt:
$$ How many :white: to live?
$$ . . . . . . . |
$$ . X X X X X X |
$$ . X . . . . X |
$$ . X . . . . . |
$$ . X . . . . . |
$$ . X . X . . . |
$$ . X X X X X X |
$$ . . . . . . . |
[go]$$ How many :white: to live?
$$ . . . . . . . |
$$ . X X X X X X |
$$ . X . . . . X |
$$ . X . . . . . |
$$ . X . . . . . |
$$ . X . X . . . |
$$ . X X X X X X |
$$ . . . . . . . |[/go]
My solution:
$$ 7 stones needed
$$ . . . . . . . |
$$ . X X X X X X |
$$ . X . . O O X |
$$ . X . . . . O |
$$ . X . O . O . |
$$ . X . X . O O |
$$ . X X X X X X |
$$ . . . . . . . |
[go]$$ 7 stones needed
$$ . . . . . . . |
$$ . X X X X X X |
$$ . X . . O O X |
$$ . X . . . . O |
$$ . X . O . O . |
$$ . X . X . O O |
$$ . X X X X X X |
$$ . . . . . . . |[/go]
Re: Interesting go problem from Daiki Komatsu twitter
Posted: Wed Nov 02, 2016 2:33 pm
by Uberdude
I was thinking it might be a bit of a trick question in that you can use fewer white moves by also adding black moves as below, but such shapes probably require too much connection. Could be a nice idea for composing another problem though.
$$B
$$ . . . . . . .
$$ . . O O O O .
$$ . O . O . O .
$$ . O O O O . .
$$ . . . . . . .
[go]$$B
$$ . . . . . . .
$$ . . O O O O .
$$ . O X . X O .
$$ . O O O O . .
$$ . . . . . . .[/go]
Re: Interesting go problem from Daiki Komatsu twitter
Posted: Wed Nov 02, 2016 3:07 pm
by Cassandra
$$
$$ . . . . . . . |
$$ . X X X X X X |
$$ . X O O O . X |
$$ . X O . O O . |
$$ . X . O . O . |
$$ . X . X O O . |
$$ . X X X X X X |
$$ . . . . . . . |
[go]$$
$$ . . . . . . . |
$$ . X X X X X X |
$$ . X O O O . X |
$$ . X O . O O . |
$$ . X . O . O . |
$$ . X . X O O . |
$$ . X X X X X X |
$$ . . . . . . . |[/go]
The minimum size for a living group in the centre with "closed borders" is 10 stones.
>>> No chance to create an "open borders" shape with less stones.
$$
$$ . . . . . . . |
$$ . X X X X X X |
$$ . X . . O O X |
$$ . X . . O . O |
$$ . X . . O O . |
$$ . X . X . O O |
$$ . X X X X X X |
$$ . . . . . . . |
[go]$$
$$ . . . . . . . |
$$ . X X X X X X |
$$ . X . . O O X |
$$ . X . . O . O |
$$ . X . . O O . |
$$ . X . X . O O |
$$ . X X X X X X |
$$ . . . . . . . |[/go]
The minimum size for a living group at the edge of the board with "closed borders" is 8 stones.
$$
$$ . . . . . . . |
$$ . X X X X X X |
$$ . X . . O O X |
$$ . X . . O . O |
$$ . X . . P O . |
$$ . X . X . O O |
$$ . X X X X X X |
$$ . . . . . . . |
[go]$$
$$ . . . . . . . |
$$ . X X X X X X |
$$ . X . . O O X |
$$ . X . . O . O |
$$ . X . . P O . |
$$ . X . X . O O |
$$ . X X X X X X |
$$ . . . . . . . |[/go]
The marked white covers a potential cutting point.
$$
$$ . . . . . . . |
$$ . X X X X X X |
$$ . X . . O O X |
$$ . X . . O . O |
$$ . X . O . O . |
$$ . X . X . O O |
$$ . X X X X X X |
$$ . . . . . . . |
[go]$$
$$ . . . . . . . |
$$ . X X X X X X |
$$ . X . . O O X |
$$ . X . . O . O |
$$ . X . O . O . |
$$ . X . X . O O |
$$ . X X X X X X |
$$ . . . . . . . |[/go]
No option left for Black to cut.
$$
$$ . . . . . . . |
$$ . X X X X X X |
$$ . X . . O O X |
$$ . X . . P . O |
$$ . X . O . O . |
$$ . X . X . O O |
$$ . X X X X X X |
$$ . . . . . . . |
[go]$$
$$ . . . . . . . |
$$ . X X X X X X |
$$ . X . . O O X |
$$ . X . . P . O |
$$ . X . O . O . |
$$ . X . X . O O |
$$ . X X X X X X |
$$ . . . . . . . |[/go]
The marked stone is not necessary any longer.
$$
$$ . . . . . . . |
$$ . X X X X X X |
$$ . X . . O O X |
$$ . X . . . . O |
$$ . X . O . O . |
$$ . X . X . O O |
$$ . X X X X X X |
$$ . . . . . . . |
[go]$$
$$ . . . . . . . |
$$ . X X X X X X |
$$ . X . . O O X |
$$ . X . . . . O |
$$ . X . O . O . |
$$ . X . X . O O |
$$ . X X X X X X |
$$ . . . . . . . |[/go]