I recently came across an interesting game in one of the online tournaments:
$$B $$ ---------------------- $$ X . X X O . . . . . . | $$ . X . X O . X X W . . | $$ X X X O O . . O X . . | $$ . . . . O . . O X . . | $$ X X . O X X . O X O . | $$ . X O . . . O O O X . | $$ O O O X X X O X X . X | $$ . O X X . O . O X X X | $$ . . . . X O . O . O X | $$ . . . . X O O . O . O | $$ . . . . X X X O . O . | $$
[go]$$B $$ ---------------------- $$ X . X X O . . . . . . | $$ . X . X O . X X W . . | $$ X X X O O . . O X . . | $$ . . . . O . . O X . . | $$ X X . O X X . O X O . | $$ . X O . . . O O O X . | $$ O O O X X X O X X . X | $$ . O X X . O . O X X X | $$ . . . . X O . O . O X | $$ . . . . X O O . O . O | $$ . . . . X X X O . O . | $$[/go]
The question is, after white's move, can black defend the corner without a ko?
Re: Interesting go problem from a real game
Posted: Fri Sep 02, 2016 3:10 am
by dhu163
$$W $$ ---------------------- $$ X . X X O . . . X . . | $$ . X . X O . X X X X 3 | $$ X X X O O . . O X O . | $$ . . . . O . . O X O 1 | $$ X X . O X X . O X O 4 | $$ . X O . . . O O O X 2 | $$ O O O X X X O X X . X | $$ . O X X . O . O X X X | $$ . . . . X O . O . O X | $$ . . . . X O O . O . O | $$ . . . . X X X O . O . | $$
[go]$$W $$ ---------------------- $$ X . X X O . . . X . . | $$ . X . X O . X X X X 3 | $$ X X X O O . . O X O . | $$ . . . . O . . O X O 1 | $$ X X . O X X . O X O 4 | $$ . X O . . . O O O X 2 | $$ O O O X X X O X X . X | $$ . O X X . O . O X X X | $$ . . . . X O . O . O X | $$ . . . . X O O . O . O | $$ . . . . X X X O . O . | $$[/go]
I think so
Re: Interesting go problem from a real game
Posted: Fri Sep 02, 2016 3:16 am
by Shaddy
dhu163 wrote:
$$W $$ ---------------------- $$ X . X X O . . . X . . | $$ . X . X O . X X X X 3 | $$ X X X O O . . O X O . | $$ . . . . O . . O X O 1 | $$ X X . O X X . O X O 4 | $$ . X O . . . O O O X 2 | $$ O O O X X X O X X . X | $$ . O X X . O . O X X X | $$ . . . . X O . O . O X | $$ . . . . X O O . O . O | $$ . . . . X X X O . O . | $$
[go]$$W $$ ---------------------- $$ X . X X O . . . X . . | $$ . X . X O . X X X X 3 | $$ X X X O O . . O X O . | $$ . . . . O . . O X O 1 | $$ X X . O X X . O X O 4 | $$ . X O . . . O O O X 2 | $$ O O O X X X O X X . X | $$ . O X X . O . O X X X | $$ . . . . X O . O . O X | $$ . . . . X O O . O . O | $$ . . . . X X X O . O . | $$[/go]
$$W $$ ---------------------- $$ X . X X O . . . . . . | $$ . X . X O . X X 1 2 . | $$ X X X O O . . O X . . | $$ . . . . O . . O X . 3 | $$ X X . O X X . O X O . | $$ . X O . . . O O O X . | $$ O O O X X X O X X . X | $$ . O X X . O . O X X X | $$ . . . . X O . O . O X | $$ . . . . X O O . O . O | $$ . . . . X X X O . O . | $$
[go]$$W $$ ---------------------- $$ X . X X O . . . . . . | $$ . X . X O . X X 1 2 . | $$ X X X O O . . O X . . | $$ . . . . O . . O X . 3 | $$ X X . O X X . O X O . | $$ . X O . . . O O O X . | $$ O O O X X X O X X . X | $$ . O X X . O . O X X X | $$ . . . . X O . O . O X | $$ . . . . X O O . O . O | $$ . . . . X X X O . O . | $$[/go]
Ko. I don't see any way for Black to keep the whole corner, at least the 2 stones on top are going to get ko'd.
Re: Interesting go problem from a real game
Posted: Fri Sep 02, 2016 3:19 am
by Tryss
Edit : same idea as Shaddy
White won't play like that in this line :
$$B $$ ---------------------- $$ X . X X O . . . 3 . . | $$ . X . X O . X X W 1 . | $$ X X X O O . . O X 2 . | $$ . . . . O . . O X . 4 | $$ X X . O X X . O X O . | $$ . X O . . . O O O X . | $$ O O O X X X O X X . X | $$ . O X X . O . O X X X | $$ . . . . X O . O . O X | $$ . . . . X O O . O . O | $$ . . . . X X X O . O . | $$
[go]$$B $$ ---------------------- $$ X . X X O . . . 3 . . | $$ . X . X O . X X W 1 . | $$ X X X O O . . O X 2 . | $$ . . . . O . . O X . 4 | $$ X X . O X X . O X O . | $$ . X O . . . O O O X . | $$ O O O X X X O X X . X | $$ . O X X . O . O X X X | $$ . . . . X O . O . O X | $$ . . . . X O O . O . O | $$ . . . . X X X O . O . | $$[/go]
Re: Interesting go problem from a real game
Posted: Fri Sep 02, 2016 10:57 am
by skydyr
The empty triangle looks good to me at first, but...
$$B $$ ---------------------- $$ X . X X O . . . . . . | $$ . X . X O . X X W 2 3 | $$ X X X O O . . O X 1 6 | $$ . . . . O . . O X . 4 | $$ X X . O X X . O X O . | $$ . X O . . . O O O X 5 | $$ O O O X X X O X X . X | $$ . O X X . O . O X X X | $$ . . . . X O . O . O X | $$ . . . . X O O . O . O | $$ . . . . X X X O . O . | $$
[go]$$B $$ ---------------------- $$ X . X X O . . . . . . | $$ . X . X O . X X W 2 3 | $$ X X X O O . . O X 1 6 | $$ . . . . O . . O X . 4 | $$ X X . O X X . O X O . | $$ . X O . . . O O O X 5 | $$ O O O X X X O X X . X | $$ . O X X . O . O X X X | $$ . . . . X O . O . O X | $$ . . . . X O O . O . O | $$ . . . . X X X O . O . | $$[/go]
However, does black need to play :b3?
$$B $$ ---------------------- $$ X . X X O . 8 6 9 7 0 | $$ . X . X O . X X W 2 4 | $$ X X X O O . . O X 1 . | $$ . . . . O . . O X . 3 | $$ X X . O X X . O X O 5 | $$ . X O . . . O O O X . | $$ O O O X X X O X X . X | $$ . O X X . O . O X X X | $$ . . . . X O . O . O X | $$ . . . . X O O . O . O | $$ . . . . X X X O . O . | $$
[go]$$B $$ ---------------------- $$ X . X X O . 8 6 9 7 0 | $$ . X . X O . X X W 2 4 | $$ X X X O O . . O X 1 . | $$ . . . . O . . O X . 3 | $$ X X . O X X . O X O 5 | $$ . X O . . . O O O X . | $$ O O O X X X O X X . X | $$ . O X X . O . O X X X | $$ . . . . X O . O . O X | $$ . . . . X O O . O . O | $$ . . . . X X X O . O . | $$[/go]
This seems to work:
$$B $$ ---------------------- $$ X . X X O . O O 1 . O | $$ . X . X O . X X O O O | $$ X X X O O . . O X X . | $$ . . . . O . . O X . X | $$ X X . O X X . O X O X | $$ . X O . . . O O O X . | $$ O O O X X X O X X . X | $$ . O X X . O . O X X X | $$ . . . . X O . O . O X | $$ . . . . X O O . O . O | $$ . . . . X X X O . O . | $$
[go]$$B $$ ---------------------- $$ X . X X O . O O 1 . O | $$ . X . X O . X X O O O | $$ X X X O O . . O X X . | $$ . . . . O . . O X . X | $$ X X . O X X . O X O X | $$ . X O . . . O O O X . | $$ O O O X X X O X X . X | $$ . O X X . O . O X X X | $$ . . . . X O . O . O X | $$ . . . . X O O . O . O | $$ . . . . X X X O . O . | $$[/go]
However:
$$B $$ ---------------------- $$ X . X X O . . 7 . 6 . | $$ . X . X O . X X W 2 4 | $$ X X X O O . 8 O X 1 . | $$ . . . . O . . O X . 3 | $$ X X . O X X . O X O 5 | $$ . X O . . . O O O X . | $$ O O O X X X O X X . X | $$ . O X X . O . O X X X | $$ . . . . X O . O . O X | $$ . . . . X O O . O . O | $$ . . . . X X X O . O . | $$
[go]$$B $$ ---------------------- $$ X . X X O . . 7 . 6 . | $$ . X . X O . X X W 2 4 | $$ X X X O O . 8 O X 1 . | $$ . . . . O . . O X . 3 | $$ X X . O X X . O X O 5 | $$ . X O . . . O O O X . | $$ O O O X X X O X X . X | $$ . O X X . O . O X X X | $$ . . . . X O . O . O X | $$ . . . . X O O . O . O | $$ . . . . X X X O . O . | $$[/go]
So perhaps:
$$B $$ ---------------------- $$ X . X X O . . 9 . 6 . | $$ . X . X O . X X W 2 4 | $$ X X X O O . 7 O X 1 . | $$ . . . . O . 8 O X . 3 | $$ X X . O X X . O X O 5 | $$ . X O . . . O O O X . | $$ O O O X X X O X X . X | $$ . O X X . O . O X X X | $$ . . . . X O . O . O X | $$ . . . . X O O . O . O | $$ . . . . X X X O . O . | $$
[go]$$B $$ ---------------------- $$ X . X X O . . 9 . 6 . | $$ . X . X O . X X W 2 4 | $$ X X X O O . 7 O X 1 . | $$ . . . . O . 8 O X . 3 | $$ X X . O X X . O X O 5 | $$ . X O . . . O O O X . | $$ O O O X X X O X X . X | $$ . O X X . O . O X X X | $$ . . . . X O . O . O X | $$ . . . . X O O . O . O | $$ . . . . X X X O . O . | $$[/go]
And now black has enough liberties for the fight.
Re: Interesting go problem from a real game
Posted: Fri Sep 02, 2016 11:34 am
by Shaddy
skydyr - still not enough liberties.
Re: Interesting go problem from a real game
Posted: Fri Sep 02, 2016 12:18 pm
by skydyr
Shaddy wrote:skydyr - still not enough liberties.
In the last diagram? I don't see it, so could you explain?
That said, I think on re-examination, white can play at instead and black can either play an unfavourable ko or connect and let white connect under.
Edit: Nevermind, I'm still counting four for some reason.
Re: Interesting go problem from a real game
Posted: Sun Sep 11, 2016 3:51 pm
by phillip1882
$$W $$ ---------------------- $$ X . X X O . . . 6 . . | $$ . X . X O . X X 1 2 . | $$ X X X O O . . O X 5 . | $$ . . . . O . . O X . 3 | $$ X X . O X X . O X O . | $$ . X O . . . O O O X 4 | $$ O O O X X X O X X . X | $$ . O X X . O . O X X X | $$ . . . . X O . O . O X | $$ . . . . X O O . O . O | $$ . . . . X X X O . O . | $$
[go]$$W $$ ---------------------- $$ X . X X O . . . 6 . . | $$ . X . X O . X X 1 2 . | $$ X X X O O . . O X 5 . | $$ . . . . O . . O X . 3 | $$ X X . O X X . O X O . | $$ . X O . . . O O O X 4 | $$ O O O X X X O X X . X | $$ . O X X . O . O X X X | $$ . . . . X O . O . O X | $$ . . . . X O O . O . O | $$ . . . . X X X O . O . | $$[/go]
$$W $$ ---------------------- $$ X . X X O . . . X . . | $$ . X . X O . X X 2 X 1 | $$ X X X O O . . O X O . | $$ . . . . O . . O X . O | $$ X X . O X X . O X O . | $$ . X O . . . O O O X X | $$ O O O X X X O X X . X | $$ . O X X . O . O X X X | $$ . . . . X O . O . O X | $$ . . . . X O O . O . O | $$ . . . . X X X O . O . | $$
[go]$$W $$ ---------------------- $$ X . X X O . . . X . . | $$ . X . X O . X X 2 X 1 | $$ X X X O O . . O X O . | $$ . . . . O . . O X . O | $$ X X . O X X . O X O . | $$ . X O . . . O O O X X | $$ O O O X X X O X X . X | $$ . O X X . O . O X X X | $$ . . . . X O . O . O X | $$ . . . . X O O . O . O | $$ . . . . X X X O . O . | $$[/go]
now what for white?
Re: Interesting go problem from a real game
Posted: Sun Sep 11, 2016 4:44 pm
by Schachus
Phillip:
$$W $$ ---------------------- $$ X . X X O . . . X . . | $$ . X . X O . X X . X . | $$ X X X O O . . O X O . | $$ . . . . O . . O X a O | $$ X X . O X X . O X O b | $$ . X O . . . O O O X X | $$ O O O X X X O X X . X | $$ . O X X . O . O X X X | $$ . . . . X O . O 1 O X | $$ . . . . X O O . O . O | $$ . . . . X X X O . O . | $$
[go]$$W $$ ---------------------- $$ X . X X O . . . X . . | $$ . X . X O . X X . X . | $$ X X X O O . . O X O . | $$ . . . . O . . O X a O | $$ X X . O X X . O X O b | $$ . X O . . . O O O X X | $$ O O O X X X O X X . X | $$ . O X X . O . O X X X | $$ . . . . X O . O 1 O X | $$ . . . . X O O . O . O | $$ . . . . X X X O . O . | $$[/go]
Black is captured, because he cant approach a, so white b next captures.
Re: Interesting go problem from a real game
Posted: Mon Sep 12, 2016 12:46 am
by gamesorry
Thanks, so it does seem that a ko is unavoidable.
FYI, the original game is here. I missed white's refusal at (4,1) at first glance.
Re: Interesting go problem from a real game
Posted: Mon Sep 12, 2016 10:18 pm
by rafaelclp
Schachus wrote:Phillip:
$$W $$ ---------------------- $$ X . X X O . . . X . . | $$ . X . X O . X X . X . | $$ X X X O O . . O X O . | $$ . . . . O . . O X a O | $$ X X . O X X . O X O b | $$ . X O . . . O O O X X | $$ O O O X X X O X X . X | $$ . O X X . O . O X X X | $$ . . . . X O . O 1 O X | $$ . . . . X O O . O . O | $$ . . . . X X X O . O . | $$
[go]$$W $$ ---------------------- $$ X . X X O . . . X . . | $$ . X . X O . X X . X . | $$ X X X O O . . O X O . | $$ . . . . O . . O X a O | $$ X X . O X X . O X O b | $$ . X O . . . O O O X X | $$ O O O X X X O X X . X | $$ . O X X . O . O X X X | $$ . . . . X O . O 1 O X | $$ . . . . X O O . O . O | $$ . . . . X X X O . O . | $$[/go]
Black is captured, because he cant approach a, so white b next captures.
I still don't get why black dies. Wouldn't 5 below save black if white played as expected above?
$$B $$ ---------------------- $$ X . X X O . . . 3 . . | $$ . X . X O . X X . 1 5 | $$ X X X O O . . O X 2 . | $$ . . . . O . . O X . 4 | $$ X X . O X X . O X O . | $$ . X O . . . O O O X . | $$ O O O X X X O X X . X | $$ . O X X . O . O X X X | $$ . . . . X O . O 6 O X | $$ . . . . X O O . O . O | $$ . . . . X X X O . O . | $$
[go]$$B $$ ---------------------- $$ X . X X O . . . 3 . . | $$ . X . X O . X X . 1 5 | $$ X X X O O . . O X 2 . | $$ . . . . O . . O X . 4 | $$ X X . O X X . O X O . | $$ . X O . . . O O O X . | $$ O O O X X X O X X . X | $$ . O X X . O . O X X X | $$ . . . . X O . O 6 O X | $$ . . . . X O O . O . O | $$ . . . . X X X O . O . | $$[/go]
instead and black can either play an unfavourable ko or connect and let white connect under.