This is a common corner shape, with many complications.
(;AP[goproblems]AB[pr]AB[pq]AB[qq]AB[oq]AW[or]AW[nr]AW[nq]AW[kq]AW[pp]AW[qp]AW[op]AW[qn]C[Black to play](;B[rr];W[rp]C[CHOICE](;B[qs]LB[rr:1]LB[rp:2]LB[qs:3]C[Dipping down at 1 is the key. If White 2, Black makes two eyes with 3. RIGHT])(;B[rq];W[qs](;B[rs];W[ps])(;B[ps];W[sq](;B[rs];W[sr])(;B[sr];W[rs]))(;B[sq];W[ps]))(;B[ps];W[qs](;B[rq];W[sq](;B[rs];W[sr])(;B[sr];W[rs]))(;B[sr];W[rs])(;B[rs];W[sr](;B[sq];W[rq])(;B[rq];W[sq]))(;B[sq];W[rq](;B[rs];W[sr])(;B[sr];W[rs])))(;B[sr];W[qs](;B[ps];W[rs])(;B[rs];W[ps]))(;B[rs];W[sr](;B[sq];W[rq])(;B[rq];W[sq]))(;B[sq];W[qs](;B[ps];W[rq](;B[sr];W[rs])(;B[rs];W[sr]))(;B[rs];W[ps])(;B[rq];W[ps])))(;B[rp];W[rr];B[rq];W[ro])(;B[rq];W[rp](;B[rr];W[qs](;B[ps];W[sq](;B[rs];W[sr])(;B[sr];W[rs]))(;B[rs];W[ps])(;B[sq];W[ps])(;B[sp];W[ps]))(;B[rs];W[sr](;B[rr];W[sq])(;B[sq];W[ps](;B[rr];W[qs])(;B[qs];W[rr]))(;B[ps];W[sq]))(;B[qs];W[rr](;B[rs];W[sr])(;B[sr];W[rs]))(;B[sr];W[rs](;B[qs];W[rr])(;B[rr];W[qs]))(;B[sq];W[rr]))(;B[sq];W[rr])(;B[qs];W[rr]))