(;AB[ab]AB[bb]AB[cc]AB[bd]AB[be]AB[ce]AB[df]AB[ef]AB[ee]AB[ed]AB[fd]AB[fc]AB[fb]AB[fa]AW[ea]AW[eb]AW[ec]AW[dc]AW[dd]AW[de]AW[cb]AW[ba]AW[cf]AW[bf]AW[ch]AW[dg]AW[eh]AW[ae]TR[ae]C[I thought the triangled move would let White live unconditionally. Show me why that's not true!]AW[bh]AP[goproblems]
(;B[aa];W[bc]
(;B[ac];W[cd]
(;B[ca];W[bc]C[Thanks to A19 Black has a chance to kill White with ko.RIGHT])
(;B[da];W[bc]C[Thanks to A19 Black has a chance to kill White with ko.RIGHT])
(;B[db];W[da]
(;B[ca];W[bc]C[Dead in double ko.])
(;B[bc];W[ad])
(;B[ad];W[bc]))
(;B[bc];W[ad])
(;B[ad];W[bc]))
(;B[ca];W[cd])
(;B[ad];W[ac])
(;B[db];W[ac])
(;B[cd];W[ad])
(;B[da];W[ac]))
(;B[ad];W[af]
(;B[cd];W[da]C[White is alive in seki. If Black plays A19 White kills Black at A17.])
(;B[bc];W[da]C[White is alive in seki.])
(;B[aa];W[cd]
(;B[ca];W[bc])
(;B[bc];W[ac])
(;B[da];W[bc])
(;B[db];W[bc])
(;B[ac];W[bc]))
(;B[ac];W[da]
(;B[aa];W[cd];B[ca];W[bc]C[Black is dead in double ko.])
(;B[cd]C[White lives in seki.]))
(;B[ca];W[da]
(;B[aa];W[cd]
(;B[ca];W[bc])
(;B[bc];W[ac])
(;B[ac];W[bc]))
(;B[cd]C[White is alive in seki. If Black plays A19 White kills Black at A17.])
(;B[bc]C[White lives in seki.])
(;B[ac];W[cd]))
(;B[da];W[bc]
(;B[cd];W[ac])
(;B[ac];W[ca]
(;B[cd];W[db]C[White lives in seki.])
(;B[aa];W[db]C[White lives in seki.]))
(;B[aa];W[ac])
(;B[ca];W[cd])
(;B[db];W[ca]
(;B[ac];W[cd])
(;B[db];W[cd])
(;B[da];W[cd])
(;B[cd];W[ac])
(;B[aa];W[ac])))
(;B[db];W[da]
(;B[aa];W[cd]
(;B[ca];W[bc])
(;B[bc];W[ac])
(;B[ac];W[bc]))
(;B[cd]C[White is alive in seki. If Black plays A19 White kills Black at A17.])
(;B[bc]C[White lives in seki.])
(;B[ac];W[cd])))
(;B[cd];W[ad];B[bc];W[da]C[Black is dead.])
(;B[ac];W[da]
(;B[cd];W[af]
(;B[aa];W[ad];B[ca];W[bc])
(;B[ad]C[White lives in seki.]))
(;B[ad];W[af]
(;B[aa];W[cd];B[ca];W[bc]C[Black is dead in double ko.])
(;B[cd]C[White lives in seki.]))
(;B[aa];W[cd]
(;B[ca];W[bc]C[Dead in double ko.])
(;B[bc];W[ad])
(;B[ad];W[bc])))
(;B[bc];W[ad])
(;B[ca];W[da]
(;B[aa];W[bc]
(;B[ac];W[cd])
(;B[cd];W[ad])
(;B[ad];W[ac])
(;B[ca];W[cd]))
(;B[cd];W[ad])
(;B[bc];W[ad])
(;B[ad];W[bc]
(;B[ac];W[af])
(;B[cd];W[ac])
(;B[aa];W[ac])
(;B[af];W[cd]
(;B[ac];W[cc]C[Black loses the capturing race.])
(;B[ae];W[ag])
(;B[aa];W[ac])))
(;B[ac];W[cd]
(;B[ad];W[af])
(;B[bc])
(;B[aa]C[White is alive. White can even pass now. If Black takes at C19 White kills Black in double ko at B17.])))
(;B[da];W[ad]
(;B[ca];W[db]
(;B[ca];W[ac]C[White lives in seki.])
(;B[bc];W[ca])
(;B[cd];W[bc])
(;B[ac];W[af]
(;B[ca]C[White lives in sente with seki.])
(;B[cd];W[bc])
(;B[aa];W[bc])
(;B[da];W[ca])
(;B[bc];W[ca]))
(;B[aa];W[bc]
(;B[ca];W[cd])
(;B[ac];W[bc])))
(;B[cd];W[bc])
(;B[bc];W[ca]
(;B[aa];W[db])
(;B[cd];W[db])
(;B[ac];W[af]))
(;B[ac];W[af]
(;B[ca];W[db]
(;B[ca]C[White lives in sente with seki.])
(;B[cd];W[bc])
(;B[aa];W[bc])
(;B[da];W[ca])
(;B[bc];W[ca]))
(;B[cd];W[bc])
(;B[bc];W[ca])
(;B[db];W[ca])
(;B[aa];W[bc]))
(;B[aa];W[bc]
(;B[ac];W[bc])
(;B[ca];W[cd])
(;B[db];W[cd]))
(;B[db];W[ca]))
(;B[db];W[da]
(;B[aa];W[bc]
(;B[ac])
(;B[cd];W[ad])
(;B[ad];W[ac])
(;B[ca];W[cd]))
(;B[cd];W[ad])
(;B[bc];W[ad])
(;B[ad];W[bc]
(;B[ac])
(;B[cd];W[ac])
(;B[aa])
(;B[af];W[cd]
(;B[ac];W[cc]C[Black loses the capturing race.])
(;B[ae];W[ag])
(;B[aa];W[ac])))
(;B[ac];W[cd]
(;B[ad];W[af])
(;B[bc])
(;B[aa]C[White is alive. White can even pass now. If Black takes at C19 White kills Black in double ko at B17.])))
(;B[af];W[ag]
(;B[aa];W[bc]
(;B[ac];W[cd]
(;B[ca];W[bc]C[Black now has a chance to kill White with ko.RIGHT])
(;B[da];W[bc]C[Black now has a chance to kill White with ko.RIGHT])
(;B[db];W[da];B[ca];W[bc]C[Double ko; black is dead.]))
(;B[ca];W[cd])
(;B[da];W[cd])
(;B[db];W[ac])
(;B[ad];W[ac])
(;B[cd];W[ac]))
(;B[ca];W[da]
(;B[aa];W[bc]
(;B[ac];W[cd];B[ca];W[bc]C[Double ko; black is dead.])
(;B[ca];W[cd])
(;B[ad];W[ac]))
(;B[cd];W[ad])
(;B[bc];W[ad])
(;B[ac];W[cd]
(;B[aa]C[Black is dead; even if White passes now, Black dies in double ko after Black C19, White B17.])
(;B[ad];W[af]))
(;B[ad];W[bc];B[ac];W[cd];B[af];W[bc]C[Black is dead in double ko.]))
(;B[da];W[ad]
(;B[ca];W[db]
(;B[ca];W[ac]C[White lives in seki.])
(;B[bc];W[ca])
(;B[ac];W[af];B[ca]C[White lives in seki.])
(;B[aa];W[bc]
(;B[ca];W[cd])
(;B[ac];W[bc])))
(;B[ac];W[af]
(;B[bc];W[ca])
(;B[ca];W[db];B[ca]C[White lives in seki.])
(;B[db];W[ca]))
(;B[bc];W[ca]))
(;B[db];W[da]
(;B[aa];W[bc]
(;B[ac];W[cd])
(;B[ca];W[cd])
(;B[ad];W[ac]))
(;B[cd];W[ad])
(;B[bc];W[ad])
(;B[ac];W[cd]
(;B[aa]C[Black is dead; even if White passes now, Black dies in double ko after Black C19, White B17.])
(;B[ad];W[af]))
(;B[ad];W[bc];B[ac];W[cd];B[af];W[bc]C[Black is dead in double ko.]))
(;B[ad];W[bc]
(;B[ac];W[cd];B[af];W[bc]C[Black is dead with double ko.])
(;B[af];W[cd];B[ac];W[cc])
(;B[ca];W[cd])
(;B[db];W[cd])
(;B[da];W[cd]))
(;B[cd];W[ad])
(;B[ac];W[da]
(;B[cd];W[af]
(;B[aa];W[ad];B[ca];W[bc])
(;B[ad]))
(;B[ad];W[cd];B[af];W[bc]C[Black is dead in double ko.])
(;B[aa];W[cd])
(;B[bc];W[cd]))
(;B[bc];W[ad]
(;B[da];W[ca])
(;B[cd];W[da])
(;B[aa];W[ca])
(;B[ac];W[af])
(;B[ca];W[da])
(;B[db];W[da]))
(;B[bg];W[ad])))