(;AW[or]AW[os]AB[pr]AB[ps]AB[nr]AB[oq]AB[op]AB[pp]AB[oo]AB[po]AB[qo]AB[no]AB[nn]AB[mn]AB[in]AB[jn]AB[kn]AB[ln]AB[im]AW[hm]AW[hn]AW[io]AW[jo]AW[lo]AW[ko]AW[mo]AW[np]AW[nq]AW[hl]AB[il]C[Defend against the marked stone]AB[ik]AW[hk]TR[nr]AP[goproblems]
(;W[mr];B[ms]C[CHOICE]
(;W[lr];B[ls];W[ks];B[ns]
(;W[kr]C[Not the most optimal defense but okay =DRIGHT])
(;W[jr]C[Not the most optimal defense but okay =DRIGHT]))
(;W[ls];B[mq];W[ns];B[mp]
(;W[nr];B[lr])
(;W[lq];B[nr];W[nq];B[lp];W[kp];B[np]
(;W[kq];B[nr];W[ms];B[nq]C[Bass' SolutionRIGHT])
(;W[kr];B[nr];W[ms];B[nq]C[Bass's Solution v2RIGHT])
(;W[lr];B[nr];W[ms];B[kq]
(;W[nq];B[kr]
(;W[jq];B[ks])
(;W[jr];B[ks])
(;W[js];B[ks])
(;W[ks];B[js]))
(;W[kr];B[jq];W[jr];B[iq];W[ir];B[ho];W[hp];B[go];W[ip];B[hq]
(;W[hr];B[gp])
(;W[gp];B[hr]
(;W[hs];B[gs];W[is];B[js];W[nq];B[gr]C[If F1 and F2 were also empty, then this would be a 4 time multi-step ko for white, very very hard to win.])
(;W[gs]
(;B[is])
(;B[hs];W[gr];B[is];W[gq];B[js];W[nq]C[Black tenukis, white fills K4, and win or loss the ko, you still lose something])))))
(;W[nr];B[kq]
(;W[lr];B[kr]
(;W[ks];B[js])
(;W[jq];B[ks])
(;W[jr];B[ks])
(;W[js];B[ks]))
(;W[jq];B[lr]))))
(;W[ns];B[nr];W[lr];B[ls];W[ks];B[ns]
(;W[kr]C[Not the most optimal defense but okay =DRIGHT])
(;W[jr]AB[ik]AW[hk]C[Not the most optimal defense but okay =DRIGHT])))
(;W[mq];B[mr]
(;W[lr];B[lq];W[mp];B[kr])
(;W[lq];B[lr]))
(;W[lr];B[mr];W[lq];B[ls];W[ks];B[ms];W[mq];B[ns]
(;W[kr]C[BartTM's solutionRIGHT])
(;W[jr]C[Bart's Solution v2RIGHT]))
(;W[ms];B[mr])
(;W[lq];B[lr];W[mr];B[ms]
(;W[mq];B[kr])
(;W[ns];B[nr];W[kr];B[mq];W[mp];B[ks];W[kq];B[js])))