Problem	4009
Created	2004-02-29
Source	NHK Igo-no-jikan 2004.02.28
Rating

Difficulty	8 dan
Average Solve Time	76 secs
User Attempts	169 / 1601
Solve Ratio Rating	3 dan
	rating history

The original problem is, the R18 being empty, "Can black tenuki to kill?". The answer is yes. But it is too difficult, so I restricted the first white move to R18 and made the goal "black to kill".

(;AW[qb]AW[pc]AW[oc]AW[qd]AW[rd]AB[rf]AB[re]AB[qe]AB[pd]AB[od]AB[nd]AB[nc]AB[nb]AB[pe]C[black to kill. ko is not good.]AP[goproblems] (;B[ob] (;W[pb] (;B[rc];W[sd] (;B[rb];W[sb] (;B[ra];W[qc] (;B[pa]C[RIGHT]) (;B[se];W[pa] (;B[sc]C[RIGHT]) (;B[oa];W[sc]C[seki.]) (;B[sa];W[sc]) (;B[qa];W[sc])) (;B[sc];W[qa]) (;B[sa];W[qa]) (;B[qa];W[pa] (;B[se];W[sc]) (;B[oa];W[sc])) (;B[oa];W[pa] (;B[sc]C[RIGHT]) (;B[se];W[sc]C[seki]) (;B[qa];W[sc]))) (;B[qc];W[ra]) (;B[sc];W[ra]C[ko.]) (;B[pa];W[ra]) (;B[qa];W[pa] (;B[sc];W[ra]C[itte yose ko (black needs one approaching move).]) (;B[ra];W[qc] (;B[se];W[sc]) (;B[oa];W[sc])) (;B[qc];W[ra]) (;B[sa];W[ra]) (;B[se];W[ra]) (;B[oa];W[ra])) (;B[sa];W[ra]) (;B[se];W[ra])) (;B[qc];W[rb]) (;B[se];W[rb]) (;B[pa];W[rb] (;B[qa];W[ra] (;B[sb];W[sc]) (;B[sc];W[sb]) (;B[se];W[sc])) (;B[ra];W[qa];B[sb];W[qc]) (;B[sb];W[sc]) (;B[sc];W[sb] (;B[qa];W[ra]) (;B[ra];W[qa]) (;B[se];W[qc]))) (;B[qa];W[pa] (;B[rb];W[ra] (;B[sb];W[sc]) (;B[sc];W[qc]) (;B[se];W[qc];B[sb];W[sc]) (;B[oa];W[sb]) (;B[qc];W[sb])) (;B[ra];W[rb] (;B[sb];W[sc]) (;B[sc];W[sb])) (;B[sb];W[rb]) (;B[qc];W[rb]) (;B[sc];W[rb]) (;B[se];W[rb]) (;B[oa];W[rb]) (;B[sa];W[rb])) (;B[sc];W[rb] (;B[pa];W[sb] (;B[qa];W[ra]) (;B[ra];W[qa]) (;B[se];W[qc])) (;B[sb];W[pa]) (;B[ra];W[sb]) (;B[se];W[qc])) (;B[ra];W[rb] (;B[sb];W[sc]) (;B[sc];W[sb]) (;B[pa];W[qa];B[sb];W[qc])) (;B[sb];W[rb] (;B[pa];W[qa] (;B[ra];W[qc]) (;B[sc];W[qc])) (;B[ra];W[pa]))) (;B[sd];W[rc] (;B[rb];W[sb]) (;B[sb];W[sc];B[rb];W[se] (;B[pa];W[qa]) (;B[qa];W[pa]) (;B[ra];W[qa])) (;B[ra];W[sc] (;B[rb];W[qa]) (;B[pa];W[qa] (;B[rb];W[oa]) (;B[sb];W[oa])) (;B[sb];W[qa]) (;B[qa];W[pa] (;B[rb];W[sb]) (;B[sb];W[rb]))) (;B[pa];W[qa] (;B[sb];W[sc] (;B[rb];W[se]) (;B[ra];W[se])) (;B[rb];W[sb])) (;B[sc];W[sb])) (;B[sc];W[rc] (;B[sd];W[sb]) (;B[rb];W[ra] (;B[sd];W[sb]) (;B[sb];W[sd]))) (;B[rb];W[rc] (;B[sc];W[ra] (;B[sb];W[sd]) (;B[sd];W[sb])) (;B[qa];W[sb] (;B[pa];W[ra]) (;B[ra];W[pa])) (;B[sb];W[sc]) (;B[ra];W[qa]) (;B[sd];W[sb]) (;B[pa];W[ra])) (;B[sb];W[rc] (;B[rb];W[sc]) (;B[sd];W[sc];B[rb];W[se] (;B[pa];W[qa]) (;B[qa];W[pa]) (;B[ra];W[qa])) (;B[ra];W[qa] (;B[sc];W[sd]) (;B[rb];W[sc]) (;B[sd];W[sc])) (;B[sc];W[sd]) (;B[pa];W[qa])) (;B[ra];W[rb]) (;B[qa];W[pa]) (;B[pa];W[rb])) (;W[sb];B[ra];W[pb];B[rb] (;W[rc] (;B[pa]C[RIGHT]) (;B[sd];W[qa])) (;W[pa];B[rc] (;W[sd] (;B[qc]C[RIGHT]) (;B[sc]C[RIGHT])) (;W[sc];B[qc]C[RIGHT]) (;W[qc] (;B[sd]C[RIGHT]) (;B[sc]C[RIGHT]))) (;W[qa];B[rc]C[RIGHT]))) (;B[oa];W[sb] (;B[ra];W[pb] (;B[rc];W[rb] (;B[sd];W[qc]) (;B[pa];W[qa]) (;B[qa];W[pa])) (;B[qa];W[pa]) (;B[pa];W[qa]) (;B[rb];W[rc] (;B[sd];W[qa]) (;B[qa];W[pa]) (;B[pa];W[qa]) (;B[ob];W[qa])) (;B[sd];W[rb] (;B[rc];W[qc]) (;B[sc];W[rc])) (;B[sc];W[rb] (;B[sd];W[rc]) (;B[rc];W[sd]) (;B[qa];W[pa]) (;B[pa];W[qa])) (;B[ob];W[rb])) (;B[rc];W[rb] (;B[sd];W[qc]) (;B[sc];W[sd]) (;B[qc];W[sc] (;B[qc];W[pb]) (;B[pb];W[qc]) (;B[qa];W[pb])) (;B[pb];W[qc]) (;B[qa];W[pb] (;B[pa];W[ra];B[sd];W[qc]) (;B[sd];W[qc])) (;B[ra];W[pa];B[sd];W[qc])) (;B[sd];W[rc] (;B[pb];W[ra]) (;B[ra];W[pb] (;B[rb];W[qa]) (;B[qa];W[pa]) (;B[pa];W[qa])) (;B[qa];W[pb] (;B[pa];W[ra]) (;B[ra];W[pa])) (;B[pa];W[ra])) (;B[sc];W[sd]) (;B[pb];W[ra] (;B[rc];W[qc];B[sd];W[sc]) (;B[qc];W[rc]) (;B[sd];W[sc]) (;B[ob];W[qc])) (;B[qa];W[ra]) (;B[rb];W[ra]) (;B[qc];W[rc]) (;B[pa];W[qa])) (;B[rc];W[rb] (;B[sd];W[qc] (;B[sb];W[sc]C[direct ko.]) (;B[sc];W[sb] (;B[se];W[ob]) (;B[ob];W[se]) (;B[oa];W[se]) (;B[pa];W[se]) (;B[ra];W[se]) (;B[qa];W[se])) (;B[ob];W[sc]) (;B[oa];W[sc]) (;B[pa];W[sc]) (;B[qa];W[sc]) (;B[ra];W[sc]) (;B[se];W[sc])) (;B[ob];W[sc]) (;B[pb];W[sc]) (;B[sb];W[sd] (;B[sc];W[ob]) (;B[ob];W[sc]) (;B[pb];W[ob]) (;B[ra];W[pa]) (;B[pa];W[sc]) (;B[oa];W[sc]) (;B[qa];W[pa])) (;B[sc];W[sd]) (;B[qc];W[sc]) (;B[pa];W[sd]) (;B[oa];W[sd]) (;B[qa];W[sc]) (;B[ra];W[sd])) (;B[sd];W[rc] (;B[ob];W[pb] (;B[rb];W[sb]) (;B[sb];W[sc];B[rb];W[se] (;B[pa];W[qa]) (;B[qa];W[pa]) (;B[ra];W[qa])) (;B[sc];W[sb]) (;B[ra];W[sb] (;B[rb];W[qa]) (;B[qa];W[pa]) (;B[pa];W[qa])) (;B[pa];W[sb] (;B[qa];W[ra]) (;B[ra];W[qa])) (;B[qa];W[pa])) (;B[pb];W[ob]) (;B[sb];W[sc] (;B[rb];W[se] (;B[ob];W[pb] (;B[pa];W[qa]) (;B[qa];W[pa]) (;B[ra];W[qa])) (;B[pb];W[ob]) (;B[pa];W[ob] (;B[oa];W[qa]) (;B[qa];W[oa];B[na];W[ra]) (;B[pb];W[oa])) (;B[qa];W[pa])) (;B[ob];W[pb] (;B[rb];W[se] (;B[pa];W[qa]) (;B[qa];W[pa]) (;B[ra];W[qa])) (;B[pa];W[qa];B[rb];W[se]) (;B[ra];W[qa]) (;B[qa];W[pa])) (;B[pb];W[ob]) (;B[ra];W[pb];B[rb];W[se])) (;B[sc];W[sb]) (;B[rb];W[sb];B[ra];W[ob]) (;B[ra];W[pb] (;B[sc];W[sb]) (;B[sb];W[sc];B[rb];W[se]) (;B[rb];W[sb] (;B[ob];W[qa]) (;B[pa];W[qa]) (;B[se];W[sc]))) (;B[pa];W[pb] (;B[rb];W[sc] (;B[sb];W[se]) (;B[ra];W[oa])) (;B[sb];W[sc] (;B[rb];W[se]) (;B[ra];W[qa]) (;B[oa];W[qa];B[rb];W[se]) (;B[ob];W[qa];B[rb];W[se]) (;B[qa];W[oa])) (;B[ra];W[qa] (;B[sc];W[sb]) (;B[sb];W[sc]) (;B[rb];W[sc])) (;B[oa];W[qa] (;B[sc];W[sb]) (;B[rb];W[sc] (;B[sb];W[se]) (;B[ob];W[ra])) (;B[sb];W[sc];B[rb];W[se])) (;B[sc];W[sb]) (;B[qa];W[ra]) (;B[ob];W[qa] (;B[sb];W[sc] (;B[rb];W[se]) (;B[ra];W[se])) (;B[rb];W[sb]))) (;B[oa];W[sb] (;B[pb];W[ra]) (;B[ra];W[pb] (;B[rb];W[qa]) (;B[qa];W[pa]) (;B[pa];W[qa])) (;B[qa];W[ra]) (;B[pa];W[ra]) (;B[se];W[pb])) (;B[qa];W[pa])) (;B[sc];W[sd] (;B[rb];W[rc] (;B[se];W[sb]) (;B[sb];W[ra]) (;B[ob];W[sb]) (;B[ra];W[sb])) (;B[rc];W[rb]) (;B[ob];W[sb]) (;B[pb];W[ob]) (;B[ra];W[rb]) (;B[sb];W[rb]) (;B[pa];W[qa]) (;B[qc];W[rc]) (;B[qa];W[pa]) (;B[oa];W[pa])) (;B[rb];W[rc] (;B[ob];W[pb] (;B[sb];W[sc]) (;B[ra];W[qa]) (;B[sc];W[ra] (;B[sb];W[sd]) (;B[sd];W[sb])) (;B[qa];W[sb] (;B[pa];W[ra]) (;B[ra];W[pa])) (;B[pa];W[ra]) (;B[sd];W[sb])) (;B[sb];W[sc]) (;B[ra];W[sb]) (;B[pb];W[ob]) (;B[qa];W[sb] (;B[ra];W[pa]) (;B[pa];W[ra]) (;B[oa];W[ra]) (;B[pb];W[ra])) (;B[pa];W[sb] (;B[ra];W[qa] (;B[pb];W[qc] (;B[sd];W[ob]) (;B[ob];W[sd])) (;B[sd];W[pb])) (;B[sd];W[ra]) (;B[pb];W[ra]) (;B[qa];W[ra])) (;B[sc];W[sd] (;B[se];W[sb]) (;B[sb];W[ra]) (;B[ra];W[sb]) (;B[ob];W[pb] (;B[se];W[sb]) (;B[sb];W[ra])) (;B[pb];W[ob]) (;B[pa];W[sb]) (;B[qa];W[pa]) (;B[oa];W[pa])) (;B[sd];W[sb];B[ra];W[ob])) (;B[sb];W[rc] (;B[ob];W[pb] (;B[rb];W[sc]) (;B[ra];W[qa] (;B[sc];W[sd]) (;B[rb];W[sc]) (;B[sd];W[sc])) (;B[sd];W[sc];B[rb];W[se] (;B[pa];W[qa]) (;B[qa];W[pa]) (;B[ra];W[qa])) (;B[pa];W[qa]) (;B[qa];W[pa]) (;B[sc];W[sd])) (;B[sd];W[sc];B[rb];W[se] (;B[ob];W[pb]) (;B[pb];W[ob]) (;B[pa];W[ob] (;B[oa];W[qa]) (;B[qa];W[oa];B[na];W[ra]) (;B[pb];W[oa])) (;B[qa];W[pa])) (;B[rb];W[sc]) (;B[ra];W[ob]) (;B[pa];W[qa];B[pb];W[ob])) (;B[ra];W[rb]) (;B[pb];W[ob]) (;B[pa];W[sb] (;B[rc];W[rb] (;B[sd];W[qc]) (;B[qc];W[sc];B[qc];W[pb]) (;B[sc];W[sd])) (;B[ra];W[qa] (;B[rc];W[rb];B[sd];W[qc]) (;B[rb];W[rc] (;B[pb];W[qc] (;B[sd];W[ob]) (;B[ob];W[sd])) (;B[sd];W[pb])) (;B[sd];W[rc] (;B[pb];W[ob]) (;B[ob];W[pb]) (;B[rb];W[pb])) (;B[sc];W[sd]) (;B[qc];W[rc]) (;B[pb];W[ob]) (;B[ob];W[rb] (;B[sd];W[pb] (;B[rc];W[qc]) (;B[sc];W[rc]) (;B[qc];W[rc]) (;B[se];W[sc])) (;B[qc];W[pb]) (;B[pb];W[qc])) (;B[oa];W[rb] (;B[sd];W[pb] (;B[rc];W[qc]) (;B[sc];W[rc]) (;B[se];W[sc]) (;B[qc];W[rc])) (;B[qc];W[pb]) (;B[pb];W[qc]))) (;B[sd];W[rc] (;B[ra];W[qa] (;B[pb];W[ob]) (;B[ob];W[pb]) (;B[oa];W[pb])) (;B[qa];W[ra]) (;B[pb];W[ra])) (;B[pb];W[qc];B[ra];W[qa];B[sd];W[ob])) (;B[qc];W[rc]))