invalid problem set
Problem | 2026 |
Created | 2003-03-21 |
Source | |
Rating | |
Difficulty | 6 dan |
Average Solve Time | 57 secs |
User Attempts |
263 / 2696 |
Solve Ratio Rating | 3 dan |
| rating history |
White and Black both have three liberties, so whoever moves first should win, right? It's not that simple. What's the tesuji? (Ko is not sufficient)
(;AB[dc]AB[ec]AB[fc]AB[gd]AB[hd]AB[fe]AB[ff]AB[ef]AB[cd]AB[bd]AB[be]AB[bf]AB[bg]AB[bh]AB[bi]AW[cc]AW[bc]AW[dd]AW[ed]AW[fd]AW[ee]AW[de]AW[ce]AW[cf]AW[cg]AW[ch]AW[ci]AW[gc]AW[gb]AW[ge]AW[ib]C[Black to save the marked stones.]TR[dc]TR[ec]TR[fc]
(;B[db]
(;W[cb]C[CHOICE]
(;B[ba];W[ca]
(;B[da];W[ab];B[ad];W[fb];B[ac]C[RIGHT])
(;B[ac];W[ab]
(;B[da];W[ad];B[ae];W[fb]
(;B[ac]C[only ko])
(;B[bb];W[aa]
(;B[ac];W[ea])
(;B[bb];W[ea])))
(;B[ad];W[da]
(;B[ea]C[RIGHT])
(;B[bb];W[ea])
(;B[fb];W[fa]))))
(;B[da]
(;W[ba];B[ab];W[ac]
(;B[ca];W[fb]
(;B[ad]C[CHOICERIGHT])
(;B[aa];W[bb])
(;B[bb];W[aa]
(;B[ad];W[ea])
(;B[bb];W[ea];B[ab]C[RIGHT])))
(;B[ad];W[fb]
(;B[ca]C[RIGHT])
(;B[bb];W[aa]
(;B[bb];W[ea])
(;B[ca];W[ea])))
(;B[bb];W[fb]
(;B[ca];W[aa]
(;B[bb]C[RIGHT];W[ea];B[ab]C[RIGHT])
(;B[ab]C[RIGHT])
(;B[ad];W[ea]))
(;B[ad];W[aa]
(;B[bb];W[ea])
(;B[ca];W[ea])))
(;B[aa];W[fb]
(;B[ad];W[ea])
(;B[ca];W[bb])))
(;W[ab];B[ba];W[ca];B[ad];W[fb];B[ac]C[CHOICERIGHT]))
(;B[ac];W[ba]
(;B[ab];W[da]
(;B[bb];W[fb];B[ca]C[Black has connected, but not in the most profitable way.RIGHT])
(;B[ea];W[fb];B[ca]C[only ko]))
(;B[da];W[ab]))
(;B[ca];W[ba]
(;B[da];W[ab]C[White lives])
(;B[ac];W[da];B[ea];W[ca]
(;B[ab];W[fb])
(;B[aa];W[ab])
(;B[fb];W[ga]
(;B[aa];W[ab])
(;B[ab];W[fa]))))
(;B[ab];W[fb]))
(;W[bb]C[CHOICE]
(;B[ac];W[ba]
(;B[ca];W[fb]
(;B[ab];W[eb];B[ad]C[RIGHT])
(;B[ad];W[cb]))
(;B[cb];W[fb];B[ab];W[eb])
(;B[ab];W[da]
(;B[ad];W[fb])
(;B[ea];W[cb]
(;B[fb];W[ga];B[ad];W[fa];B[ca]C[ko])
(;B[ad];W[fb]
(;B[ca]C[ko])
(;B[eb];W[fa]))
(;B[ca]C[ko]))
(;B[ca];W[cb];B[ea];W[fb]C[ko])
(;B[cb];W[fb])
(;B[eb];W[ea]
(;B[fa];W[ca])
(;B[fb];W[fa])
(;B[cb];W[ca])
(;B[ad];W[fb]))
(;B[fb];W[fa]C[Ko with E19 is all that remains for black.])))
(;B[cb];W[ba]
(;B[ac];W[fb];B[ab];W[eb])
(;B[ca];W[fb]))
(;B[ca];W[ba]
(;B[ac]C[RIGHT];W[fb]
(;B[ab];W[eb];B[ad]C[RIGHT])
(;B[ad];W[cb]))
(;B[ad];W[fb];B[ac];W[cb])
(;B[ab];W[ac]
(;B[ad];W[fb];B[cb]C[RIGHT])
(;B[cb];W[fb];B[ad]C[RIGHT]))
(;B[aa];W[fb]
(;B[ac];W[ab]
(;B[ad];W[eb])
(;B[cb];W[ad];B[ae];W[eb]))
(;B[ab];W[ac])
(;B[cb];W[eb]))
(;B[cb];W[fb]))
(;B[ba];W[ca]
(;B[cb];W[aa];B[da];W[fb]
(;B[ba]C[only ko])
(;B[ac];W[ea]C[ko];B[ba]C[ko]))
(;B[da];W[aa]
(;B[ac];W[fb]
(;B[cb];W[ea];B[ba]C[ko])
(;B[ad];W[ea];B[ab];W[eb]))
(;B[cb];W[fb]
(;B[ac];W[ea];B[ba]C[ko])
(;B[ba]C[ko])))
(;B[ac];W[da]
(;B[ea];W[aa]
(;B[cb];W[fb];B[ba];W[ca]
(;B[ad];W[eb];B[ab];W[da])
(;B[da];W[fa]C[ko]))
(;B[ad];W[fa]))
(;B[cb];W[aa]
(;B[ea];W[fb];B[ba];W[ca]
(;B[da];W[fa]C[ko])
(;B[ad];W[eb];B[ab];W[da]))
(;B[ad];W[fb]))
(;B[ab];W[aa];B[ad];W[fb]C[ko])))))
(;B[bb];W[cb]
(;B[db];W[ab]
(;B[ba];W[ca]
(;B[ad];W[fb]
(;B[ac];W[aa];B[bb];W[da])
(;B[da];W[aa];B[ac];W[ea]))
(;B[da];W[aa]
(;B[ad];W[fb]
(;B[ac];W[ea])
(;B[bb];W[ea]))
(;B[bb];W[fb];B[ad];W[ea])))
(;B[ca];W[ba]C[White has two eyes.]))
(;B[ac];W[db])
(;B[ca];W[db]))
(;B[cb];W[bb]
(;B[db];W[ba];B[ac];W[fb]
(;B[ab];W[eb])
(;B[ca];W[eb]))
(;B[ba];W[db]
(;B[da];W[ca]C[Ko])
(;B[ac];W[ca];B[ab];W[aa]C[Ko]))
(;B[ac];W[db])
(;B[ca];W[db];B[eb];W[ea];B[da];W[fa])
(;B[da];W[ba]
(;B[ac];W[fb];B[eb];W[fa]
(;B[ab];W[ea])
(;B[ea];W[ca]))
(;B[eb];W[fa];B[ac];W[ea])
(;B[fb];W[fa]
(;B[ac];W[eb];B[db];W[ca])
(;B[ea];W[ga]
(;B[ca];W[db])
(;B[db];W[ca])
(;B[ac];W[db];B[eb];W[ca])))))
(;B[ac];W[db]
(;B[bb];W[cb])
(;B[cb];W[bb])
(;B[eb];W[ea]))
(;B[ca];W[db])
(;B[da];W[db]
(;B[cb];W[eb])
(;B[eb];W[cb]
(;B[ac];W[fb])
(;B[ea];W[fa];B[ca];W[ba])))
(;B[fb];W[db]))
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