(;AW[qn]AW[no]AW[oo]AW[po]AW[jp]AW[kp]AW[lp]AW[mp]AW[qp]AW[rp]AW[hq]AW[jq]AW[oq]AW[pq]AW[pr]AW[qr]AB[np]AB[op]AB[pp]AB[kq]AB[lq]AB[mq]AB[nq]AB[qq]AB[rq]AB[rr]C[Black to play.]
(;B[qs];W[nr]
(;B[ps];W[or];B[mr]C[RIGHT])
(;B[mr];W[ps]
(;B[rs];W[os];B[ms]C[RIGHT])
(;B[os];W[rs]C[White wins.])
(;B[ns];W[rs];B[or]C[White wins.];W[sq]))
(;B[os];W[or]
(;B[mr];W[ns]
(;B[ms]C[RIGHT])
(;B[rs]C[RIGHT]))
(;B[ps];W[mr])
(;B[lr];W[ls];B[ms];W[ns];B[ks];W[rs];B[ss];W[ps];B[mr];W[rs]C[Ko.]))
(;B[rs];W[mr]C[White wins.]))
(;B[rs];W[nr]
(;B[os];W[mr]C[White wins.])
(;B[mr];W[ms]
(;B[ls];W[os]LB[kr:A]C[Ko. White needs an approach move at A, but black could have killed without ko.])
(;B[kr];W[os];B[qs];W[ps];B[ls];W[js]LB[jr:A]LB[ks:B]C[Ko. White needs two more moves at A and B but black could have won unconditionally.]))
(;B[ps];W[mr]C[White wins.])
(;B[qs];W[mr]C[White wins.])
(;B[jr];W[os];B[qs];W[ps];B[mr];W[sq];B[ms];W[sr]C[White wins.]))
(;B[nr];W[rs]C[White wins])
(;B[or];W[nr]
(;B[qs];W[os];B[rs];W[ps]
(;B[mr];W[sq])
(;B[ms];W[mr]
(;B[lr];W[sq])
(;B[ls];W[lr];B[kr];W[jr];B[ks];W[js])))
(;B[os];W[ns]C[White wins.]))
(;B[ps];W[os]
(;B[nr];W[rs]C[White wins.])
(;B[rs];W[nr];B[qs];W[or]
(;B[mr]C[RIGHT])
(;B[ms]C[RIGHT])
(;B[ls]C[RIGHT])
(;B[kr]C[RIGHT])
(;B[jr]C[RIGHT])
(;B[ks]C[RIGHT])
(;B[js];W[mr];B[kr];W[jr]C[White wins.])
(;B[ns];W[mr];B[lr];W[ms];B[ls]C[RIGHT])
(;B[lr]C[RIGHT])))
(;B[os];W[rs];B[qs];W[sr]C[Ko. Black could have killed unconditionally.]))
Hans