(;GM[1]FF[4]CA[UTF-8]AP[CGoban:3]ST[2]
RU[Japanese]SZ[19]KM[0.00]
GN[163ex]PB[Black to play and live in the corner]AW[qm][on][qn][pp][qp][nq][oq]AB[qk][ro][mp][np][mq][qq]C[Black to play and live in the corner]
(;B[pq]C[This is the key first move that takes advantage of
white's shape.]
(;W[rq]C[If white plays way...]
;B[rr]C[..black can force...]
;W[rp]
;B[op]C[..then cut...]
;W[or]
;B[ps]
;W[mr]
;B[ns]C[... then kill the cut white stones.]
;W[nr]
;B[lr]
;W[pr]
;B[qr])
(;W[or]C[If white plays here instead...]
;B[pr]C[Black should play here to make miai of living and cutting
off the three white stones.]
(;W[rq]
;B[ps]C[This gains liberties for black.]
(;W[op]C[If white connect black can live as follows.]
;B[rr]
;W[rp]
;B[sr])
(;W[rr]C[If white tries to kill, black can cut and capture.]
;B[op]
;W[os]
;B[nr]
;W[qr]
;B[ns]))
(;W[op]C[If white connects here...]
(;B[rr]
;W[rp]
;B[qs]C[Black can live this way.])
(;B[rp]C[But black should not try for a big corner.]
;W[ps]
;B[rr]
;W[rs]C[This is ko for blacks life..]
;B[sq]
;W[qr])))
(;W[rp]C[If white plays this way, black just cuts.]
;B[op]
;W[pr]
;B[qr]
;W[or]
;B[ps]C[White loses the race.])
(;W[op]C[If white plays here then Black has various ways to live in the corner.]))
(;B[rp]C[If Black plays instead here, white has two ways to attack,
but they are not that easy to read out.]
(;W[qr]
;B[rr]
;W[pr]
;B[rn]
;W[rm]
;B[rs]
;W[sn]
;B[so]
;W[sq]
;B[sr]
;W[rq])
(;W[rr]))
(;B[rr]C[This doesn't work.]
;W[pr])
(;B[pr]C[Nor does this work.]
;W[rr]
;B[rq]
;W[rp]
;B[sr]
;W[rs]
;B[or]
;W[nr]
;B[os]
;W[qs]C[Dead shape.]))
