(;GM[1]FF[4]CA[UTF-8]AP[CGoban:3]ST[2]
RU[Japanese]SZ[19]KM[0.00]
GN[175ex]PB[Black to play and break into White's area]AW[jp][mp][np][op][jq][mq][pq][qq][ir][kr][lr][qr][qs]AB[ko][mo][no][oo][lp][pp][qp][kq][lq][rq][jr][rr][rs]
(;B[oq]C[This is not the right move.]
;W[or]
;B[mr]
;W[nq]
;B[nr]
;W[oq]
;B[ls]
;W[js]
;B[os]
;W[ns]
;B[ms]
;W[ks]C[Black runs out of liberties faster than White.])
(;B[mr]C[Starting with this cut is the correct move.]
(;W[or]
;B[nr]
;W[oq]
(;B[os]
(;W[ps]
;B[ms]C[Black can play here making a ko as it takes two moves for White to safely fill the liberty to the left of the cutting stones.])
(;W[js]
;B[ps]
;W[ms]C[This now a seki - both strings are alive, but White's area has gone.]))
(;B[ls]C[Mistake by Black.]
;W[js]
;B[os]
;W[ps]
;B[ms]
;W[ks]C[White is no longer short of liberties.]))
(;W[nr]C[If White plays here Black captures the four stones to the right.]
;B[oq]
;W[nq]
;B[or]
;W[ms]
;B[ps])))
