"You first need to determire whether or not you can live by simply securing the base that you have. If this won't allow you to live, then you have no choice but search out the vital point for making eye shape." (Cho Chikun, All About Life And Death, page 161)
(;AB[sq]AB[rr]AB[qq]AB[pq]AB[oq]AB[or]AW[nr]AW[nq]AW[lr]AW[op]AW[pp]AW[qp]AW[rp]AW[rq]C[Black to play and live]AP[goproblems]
(;B[qs]C[RIGHT])
(;B[sr];W[ps];B[os];W[qr])
(;B[os];W[sr]
(;B[qs];W[sp];B[pr];W[rs]C[Ko])
(;B[ss];W[qs])
(;B[rs])
(;B[qr];W[sp]
(;B[rs];W[ps])
(;B[ps];W[rs]))
(;B[pr];W[qs];B[ss];W[sp])
(;B[ps];W[qr]
(;B[ss];W[qs])
(;B[qs];W[rs])))
(;B[ps];W[sr]
(;B[qr];W[rs];B[ss]C[Ko])
(;B[ss];W[qr];B[qs];W[sp];B[pr];W[sr]C[Ko])
(;B[rs];W[qr])
(;B[pr];W[sp])
(;B[qs];W[sp]))
(;B[qr];W[sr]
(;B[ss];W[ps];B[os];W[qs])
(;B[ps];W[rs];B[ss]C[Ko])
(;B[rs];W[ps])
(;B[os];W[sp]
(;B[ps];W[rs])
(;B[rs];W[ps]))
(;B[qs];W[sp])
(;B[pr];W[sp]))
(;B[pr];W[qs]
(;B[rs]
(;W[sr])
(;W[os];B[qr];W[sr]))
(;B[sr];W[os])
(;B[ss];W[os])
(;B[ps];W[rl]C[White can tenuki now])
(;B[qr];W[rk]C[White can tenuki now. Black is dead.])
(;B[os]C[White can tenuki. Black is dead.]))
(;B[rs];W[sr]
(;B[ps];W[qr])
(;B[qr];W[ps]))
(;B[ss];W[qs]))