Problem	13864
Created	2010-07-28
Name	Comb patterns, Pattern 18
Source	All about life and death, Cho Chikun
Rating

Difficulty	8 dan
Average Solve Time	46 secs
User Attempts	274 / 677
Solve Ratio Rating	7 kyu
	rating history

White to play and make ko

(;AB[sr]AB[rr]AB[qq]AB[pq]AB[or]AW[nr]AW[nq]AW[lr]AW[op]AW[pp]AW[qp]AW[ro]AW[rq]AW[sq]AP[goproblems] (;W[qs];B[qr] (;W[os];B[ps];W[pr]C[RIGHT])) (;W[os];B[ps] (;W[qs];B[qr];W[pr]C[RIGHT]) (;W[oq] (;B[ns])) (;W[pr];B[ns]) (;W[qr];B[qs]) (;W[rs];B[qs] (;W[pr];B[ns]) (;W[qr];B[pr]))) (;W[ps];B[os];W[rs];B[qr];W[qs];B[oq]C[Seki]) (;W[rs];B[qr] (;W[ps];B[os];W[qs];B[oq]) (;W[os];B[ps];W[oq];B[ns])))