I'm presently working through the intermediate collection when I came to this particular problem, which for whatever reason has me stumped for days. Perhaps the rest of you would like a crack at it? I'll post more if there are any I find perplexing or if there seems to be any interest. Here is the original diagram:
This initial exchange is my first instinct - extend and atari. After W4, however, Black is in shortage of liberties, with no way to save the marked black stones.
[go]$$c Problem 58 - Second Attempt $$ --------------------------------------- $$ | a 3 b c . O . . O X . . . . . . . . . | $$ | 2 1 X X O O X . O X . . . . . . . . . | $$ | O O O O X O . O O X . . . . . . . . . | $$ | X O . O X O O O X X . . . . . , . . . | $$ | X O O O X . . X . . . . . . . . . . . | $$ | X X X X X . X . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . , . . . . . , . . . . . , . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . , . . . . . , . . . . . , . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ ---------------------------------------[/go]
I thought this exchange solved it. White can't play at A for fear of self-atari. If White B, then Black at C creates a seki-like situation - except of course that White will be dead. I figured that White at C would create the following situation.
[go]$$c Problem 58 - Second Attempt $$ --------------------------------------- $$ | . X 6 4 7 O . . O X . . . . . . . . . | $$ | O X X X O O X . O X . . . . . . . . . | $$ | O O O O X O . O O X . . . . . . . . . | $$ | X O . O X O O O X X . . . . . , . . . | $$ | X O O O X . 5 X . . . . . . . . . . . | $$ | X X X X X . X . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . , . . . . . , . . . . . , . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . , . . . . . , . . . . . , . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ ---------------------------------------[/go]
Black continuously saves his interior stones in snapback, using the extra tempo to capture the bulky five off the board and put a stop to the nonsense. Of course things aren't so easy.
[go]$$c Problem 58 - Second Attempt - Refuted $$ --------------------------------------- $$ | a X b 4 6 O . . O X . . . . . . . . . | $$ | O X X X O O X . O X . . . . . . . . . | $$ | O O O O X O . O O X . . . . . . . . . | $$ | X O . O X O O O X X . . . . . , . . . | $$ | X O O O X . 5 X . . . . . . . . . . . | $$ | X X X X X . X . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . , . . . . . , . . . . . , . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . , . . . . . , . . . . . , . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ ---------------------------------------[/go]
After W4, a and b are both self-atari for Black. After W6, White can atari at b and connects easily after capturing Black's stones without fear of snapback. Alas!
[go]$$c Problem 58 - Possibilities $$ --------------------------------------- $$ | . b c d . O . . O X . . . . . . . . . | $$ | . a X X O O X . O X . . . . . . . . . | $$ | O O O O X O . O O X . . . . . . . . . | $$ | X O . O X O O O X X . . . . . , . . . | $$ | X O O O X . . X . . . . . . . . . . . | $$ | X X X X X . X . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . , . . . . . , . . . . . , . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . , . . . . . , . . . . . , . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ ---------------------------------------[/go]
Perhaps a different B1 is the answer? Variations at A, B, C, and D have all been promising, but all suffer similar problems. White seems able to easily force a shortage of liberties on Black. White's bulky five shape has just enough life left in it to attack and destroy the interior black stones, and the strange properties of the 1-1 point seems to allow White to fend off any dangerous atari against the one-eyed group.
Good luck to all who attempt this dastardly problem. If you do find a solution, use the hide tags please, I haven't given up on figuring this one out yet! I'll post more variations if they seem interesting.
I thought a couple of other moves made ko too, but upon looking closer I think this is the only one.
_________________ We don't know who we are; we don't know where we are. Each of us woke up one moment and here we were in the darkness. We're nameless things with no memory; no knowledge of what went before, No understanding of what is now, no knowledge of what will be.
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NousAutres wrote:
I always feel a little disappointed when the answer is ko, but you're probably right.
These problems really annoy me, because whenever I find the solution that results in a ko (in this particular case it took me about a minute), I feel there must be something better. IMHO the problems would much better, if the correct solution was clear kill (or life) - at least then when I found the solution I would be satisfied that it really is the best solution.
In this particular problem, I thought it was fairly obvious that the answer was ko. But there are a huge number of ko problems in Cho Chikun's L&D, and not all of them are obvious. It makes it hard to know how long to keep looking for a non-ko solution.
I always feel a little disappointed when the answer is ko, but you're probably right.
These problems really annoy me, because whenever I find the solution that results in a ko (in this particular case it took me about a minute), I feel there must be something better. IMHO the problems would much better, if the correct solution was clear kill (or life) - at least then when I found the solution I would be satisfied that it really is the best solution.
What would be even better, is if during our own games, flags would come up saying "black to play and kill", or "white to live", or, "black to live in ko"
Since this is unlikely, perhaps it is best to study problems which have not such a tag - after all, in real games you do not even receive notice that there is a problem.
I always try to look for all answers, if they're ko or kill or seki or life-with-points, and then pick the least bad one I could find among them.
So if I find ko or seki, I will look if there's anything nicer, but if I can't find it in a few minutes, it's usually just not there.
I really don't like doing purely life and death problems because of this. They can leave you with the impression that ko is wrong, which is a massive oversimplification. Ko is wrong only if you don't have enough threats that are large enough. Otherwise it's the same thing as certain life.
@tsuyoku: Ko IS almost always wrong when you have unconditional life/kill (given that the result if you win the ko is the same - sometimes better to ko for more points). The only exception (as far as I know) is if you have more legit threats, the opponent has no way to ever get more threats than you, AND there's no other possibilities of ko elsewhere on the board.
@tsuyoku: Ko IS almost always wrong when you have unconditional life/kill (given that the result if you win the ko is the same - sometimes better to ko for more points). The only exception (as far as I know) is if you have more legit threats, the opponent has no way to ever get more threats than you, AND there's no other possibilities of ko elsewhere on the board.
So take your first sentence. If you clarify this as "if you're going to add one of two moves, and one move is a ko while the other move is unconditional life/kill, the latter is always better," that's correct, of course. If instead you clarify it as "if you can get a ko or you can get unconditional life/kill, the latter is always better," that's wrong (it may be better to play elsewhere and let your opponent start the ko), but this latter interpretation is much more intuitive. I think this sort of common confusion is what Tsuyoku is driving at.
The only other thing to look for in a situation like this is if it is possible to force dual ko, which in this case, it is not.
_________________ "Those who calculate greatly will win; those who calculate only a little will lose, but what of those who don't make any calculations at all!? This is why everything must be calculated, in order to foresee victory and defeat."-The Art of War
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