Tommie in GoDiscussions five years years ago: "This problem is a tough cookie". This turned out to be one of the unsolved problems. He finally proposed the first move at 8 in sverre's diagram ( ie g19 ) but had no time to explore a final solution. So let me have a try in the attached sgf. I especially like the main variant. Wasn't it Einstein who said that an elegant theory must have some truth in it? ( answer: no !)
I am going to have to set these things up on a real board in the future, aren't I?
cyclops wrote:
$$B continuation: b defeats this variant at 1 $$ +---------------------------+ $$ | 9 O 6 8 2 . 1 4 3 . . . . | $$ | X O O O X X . O . . X . . | $$ | 7 X X X O O O O X X . X . | $$ | X O . X X X O 5 . , . . . | $$ | . O . X O O X X . X . . . | $$ | X X X X . . . . . . . . . | $$ | . . . , O . O . . , . . . | $$ | . O . O . . . . . . . . . | $$ | . . . . . . . . . . . . . | $$ | . . . , . . , . . , . . . |
[go]$$B continuation: b defeats this variant at 1 $$ +---------------------------+ $$ | 9 O 6 8 2 . 1 4 3 . . . . | $$ | X O O O X X . O . . X . . | $$ | 7 X X X O O O O X X . X . | $$ | X O . X X X O 5 . , . . . | $$ | . O . X O O X X . X . . . | $$ | X X X X . . . . . . . . . | $$ | . . . , O . O . . , . . . | $$ | . O . O . . . . . . . . . | $$ | . . . . . . . . . . . . . | $$ | . . . , . . , . . , . . . |[/go]
$$B How do you deal with this W4? $$ +---------------------------+ $$ | . O . X 2 . 1 . 3 . . . . | $$ | X O O O X X 4 O . . X . . | $$ | . X X X O O O O X X . X . | $$ | X O . X X X O . . , . . . | $$ | . O . X O O X X . X . . . | $$ | X X X X . . . . . . . . . | $$ | . . . , O . O . . , . . . | $$ | . O . O . . . . . . . . . | $$ | . . . . . . . . . . . . . | $$ | . . . , . . , . . , . . . |
[go]$$B How do you deal with this W4? $$ +---------------------------+ $$ | . O . X 2 . 1 . 3 . . . . | $$ | X O O O X X 4 O . . X . . | $$ | . X X X O O O O X X . X . | $$ | X O . X X X O . . , . . . | $$ | . O . X O O X X . X . . . | $$ | X X X X . . . . . . . . . | $$ | . . . , O . O . . , . . . | $$ | . O . O . . . . . . . . . | $$ | . . . . . . . . . . . . . | $$ | . . . , . . , . . , . . . |[/go]
Looking over the sgf, I believe I may have found a way for Black to kill, by varying a move from the mainline variation. I may be hallucinating, as usual.
$$B 1-4 as in the mainline $$ ------------ $$|.O..O213..... $$|XOOO...O4.X.. $$|.XXX..OOXX.X. $$|XO.XXXO..,... $$|.O.XOOXX.X... $$|XXXX......... $$|....O.O...... $$|.O.O......... $$|.............
[go]$$B 1-4 as in the mainline $$ ------------ $$|.O..O213..... $$|XOOO...O4.X.. $$|.XXX..OOXX.X. $$|XO.XXXO..,... $$|.O.XOOXX.X... $$|XXXX......... $$|....O.O...... $$|.O.O......... $$|.............[/go]
$$B Black tries to vary by making the 1-2 exchange here... $$ ------------ $$|.O..OOXX21... $$|XOOO...OO.X.. $$|.XXX..OOXX.X. $$|XO.XXXO..,... $$|.O.XOOXX.X... $$|XXXX......... $$|....O.O...... $$|.O.O......... $$|.............
[go]$$B Black tries to vary by making the 1-2 exchange here... $$ ------------ $$|.O..OOXX21... $$|XOOO...OO.X.. $$|.XXX..OOXX.X. $$|XO.XXXO..,... $$|.O.XOOXX.X... $$|XXXX......... $$|....O.O...... $$|.O.O......... $$|.............[/go]
$$B Then we capture the White stones with the usual exchange $$ ------------ $$|.O.5OOXXOX... $$|XOOO31.OO.X.. $$|.XXX42OOXX.X. $$|XO.XXXO..,... $$|.O.XOOXX.X... $$|XXXX......... $$|....O.O...... $$|.O.O......... $$|.............
[go]$$B Then we capture the White stones with the usual exchange $$ ------------ $$|.O.5OOXXOX... $$|XOOO31.OO.X.. $$|.XXX42OOXX.X. $$|XO.XXXO..,... $$|.O.XOOXX.X... $$|XXXX......... $$|....O.O...... $$|.O.O......... $$|.............[/go]
$$W White is short on liberties if he starts at 2 $$ ------------ $$|.O.X23XXOX... $$|XOOOXX1OO.X.. $$|.XXXOOOOXX.X. $$|XO.XXXO..,... $$|.O.XOOXX.X... $$|XXXX......... $$|....O.O...... $$|.O.O......... $$|.............
[go]$$W White is short on liberties if he starts at 2 $$ ------------ $$|.O.X23XXOX... $$|XOOOXX1OO.X.. $$|.XXXOOOOXX.X. $$|XO.XXXO..,... $$|.O.XOOXX.X... $$|XXXX......... $$|....O.O...... $$|.O.O......... $$|.............[/go]
$$B Black 7 is atari on 5 white stones. $$ ------------ $$|5O6XX412OX... $$|XOOOXXOOO.X.. $$|3XXXOOOOXX.X. $$|XO.XXXO..,... $$|.O.XOOXX.X... $$|XXXX......... $$|....O.O...... $$|.O.O......... $$|.............
[go]$$B Black 7 is atari on 5 white stones. $$ ------------ $$|5O6XX412OX... $$|XOOOXXOOO.X.. $$|3XXXOOOOXX.X. $$|XO.XXXO..,... $$|.O.XOOXX.X... $$|XXXX......... $$|....O.O...... $$|.O.O......... $$|.............[/go]
[go]$$Bc Starting at a works (2 and 3 are miai) $$--------- $$|2.3.OX.. $$|1OOOOX.. $$|OXOXX.X. $$|.XX,.... $$|.X.X.... $$|........[/go]
$$Bc Starting at the "1-2" point of the shape also works (2,3 miai). $$--------- $$|.31.OX.. $$|2OOOOX.. $$|OXOXX.X. $$|.XX,.... $$|.X.X.... $$|........
[go]$$Bc Starting at the "1-2" point of the shape also works (2,3 miai). $$--------- $$|.31.OX.. $$|2OOOOX.. $$|OXOXX.X. $$|.XX,.... $$|.X.X.... $$|........[/go]
Intermediate problem
The eyeshape looks much like in the previous intermediate problem, except sente has been switched. Almost every move kills unconditionally, but I prefer the hanes since the result is not a bent 4.
Black needs to get 'a' and 'b', without giving White time to cut. Taking or threatening to take the vulnerable stone seems like a natural way to gain tempo
I couldn't figure out what to do after this, so I didn't post this answer.
My attempt:
$$B a and b are miai $$ ------------ $$|.O.aOb1...... $$|XOOO34.O2.X.. $$|.XXX5.OOXX.X. $$|XO.XXXO..,... $$|.O.XOOXX.X... $$|XXXX......... $$|....O.O...... $$|.O.O......... $$|.............
[go]$$B a and b are miai $$ ------------ $$|.O.aOb1...... $$|XOOO34.O2.X.. $$|.XXX5.OOXX.X. $$|XO.XXXO..,... $$|.O.XOOXX.X... $$|XXXX......... $$|....O.O...... $$|.O.O......... $$|.............[/go]
I couldn't figure out what to do after this, so I didn't post this answer.
My attempt:
$$B a and b are miai $$ ------------ $$|.O.aOb1...... $$|XOOO34.O2.X.. $$|.XXX5.OOXX.X. $$|XO.XXXO..,... $$|.O.XOOXX.X... $$|XXXX......... $$|....O.O...... $$|.O.O......... $$|.............
[go]$$B a and b are miai $$ ------------ $$|.O.aOb1...... $$|XOOO34.O2.X.. $$|.XXX5.OOXX.X. $$|XO.XXXO..,... $$|.O.XOOXX.X... $$|XXXX......... $$|....O.O...... $$|.O.O......... $$|.............[/go]
$$B a and b are miai $$ ------------ $$|.O.6O71..80.. $$|XOOO34.O29X.. $$|.XXX5.OOXX.X. $$|XO.XXXO..,... $$|.O.XOOXX.X... $$|XXXX......... $$|....O.O...... $$|.O.O......... $$|.............
[go]$$B a and b are miai $$ ------------ $$|.O.6O71..80.. $$|XOOO34.O29X.. $$|.XXX5.OOXX.X. $$|XO.XXXO..,... $$|.O.XOOXX.X... $$|XXXX......... $$|....O.O...... $$|.O.O......... $$|.............[/go]
$$Bm11 a and b are miai $$ ------------ $$|.O.OOXX2.OO1. $$|XOOOXO.OOXX.. $$|.XXXX.OOXX.X. $$|XO.XXXO..,... $$|.O.XOOXX.X... $$|XXXX......... $$|....O.O...... $$|.O.O......... $$|.............
[go]$$Bm11 a and b are miai $$ ------------ $$|.O.OOXX2.OO1. $$|XOOOXO.OOXX.. $$|.XXXX.OOXX.X. $$|XO.XXXO..,... $$|.O.XOOXX.X... $$|XXXX......... $$|....O.O...... $$|.O.O......... $$|.............[/go]
Ko was the best I could do the other day.
$$Bm11 a and b are miai $$ ------------ $$|.O.OOXX23451. $$|XOOOXO.OOXX.. $$|.XXXX.OOXX.X. $$|XO.XXXO..,... $$|.O.XOOXX.X... $$|XXXX......... $$|....O.O...... $$|.O.O......... $$|.............
[go]$$Bm11 a and b are miai $$ ------------ $$|.O.OOXX23451. $$|XOOOXO.OOXX.. $$|.XXXX.OOXX.X. $$|XO.XXXO..,... $$|.O.XOOXX.X... $$|XXXX......... $$|....O.O...... $$|.O.O......... $$|.............[/go]
B has bigger eyeshape and more liberties. White must win the ko what, 8+ times? Black can recoup the cost of the group by simply playing big gote moves, and unless White has many, many huge threats he can even win the ko afterwards for good measure.
at 7 in sverre's diagram?
