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Beginner Exercise 9 Solution
Difficulty: Beginner
Keywords: Problem
unkx80: In case people get lost in the large number of diagrams in the discussions below, I have reproduced the solution diagram.
First throw in at
Good work splice!
AGiss : Well, it looks like "Black is definitely alive", but, well, I've finally found a way to kill Black using the ko rule!
Now, the position looks like:
But, if White plays a now, then Black can either connect at b and White will take away the eye with c, or Black can play at c and White will separate the two eyes with b.
KarlKnechtel: Very good. Ordinarily I think Black would be said to "live in ko" after
splice: How about this? I can see two continuations from here... (Addendum: Just realized this is exactly the answer given above, but in a different order.. Well, it can lead to Black killing himself if he doesn't pay attention, saving White ko threats for later... any better? :)
KarlKnechtel: This is even better, definitely, and I scold myself for not realizing it would work. This makes ... Wait! Actually, this sequence is necessary, because Black does have one of those threats - any local ko threat is by definition big enough, and Black has one:
Quick note from AGiss: I would have played a. Why is the marked point better than a? KarlKnechtel: Oh, it's not. That empty a point really spoils my analysis here, it turns out :( If White plays there, Black can threaten a connect-and-die by playing the circled point (with b as a follow-up), but either making one of the connections or (probably better) playing at c spoils Black's last plan.
White cannot win the ko by
White 11 retakes the ko at
splice: Is
White should be safe since she can take the lone black stone. Unless I am missing something? Why does White fill??
ikkentobi : There is no need for White to fear the ko threat at
Black is dead since he has only one true eye, and the marked eye is a false eye
KarlKnechtel: The squared point spoils my first idea, but what about the circled points? True - Black can connect, but White can too, and is safe while Black's eye is still falsified. A curse on that empty point! ;) Though, it occurs to me that Black may have two ko threats at the circled points - threats to escape. Hmmm. (The rest of splice's analysis follows.)
Either Black saves his two stones at the left by taking the white stone, and White takes the ko again, most likely connecting right after (probably nothing else as big on the board)...
Or Black connects the ko and White takes the two stones, killing the group. So it ends either in a ko or in death for Black. fhayashi: Is this really Beginner-level anymore??
This is a copy of the living page "Beginner Exercise 9 Solution" at Sensei's Library. ![]() |