(;AB[aj]AB[bi]AB[ci]AB[bk]AB[dj]AB[ck]AW[bl]AW[cl]AW[dl]AW[dk]AB[ek]AB[fk]AB[fl]AW[el]AW[dm]AB[em]AW[bn]AW[cn]AB[dn]AB[en]AB[co]AB[dp]AW[fq]C[White to get the best result with the C8 group. 'T' for tenuki if you believe it's dead.]LB[fi:T]AP[goproblems] (;W[bp];B[bo];W[ao] (;B[cq]C[CHOICE] (;W[bq];B[cr] (;W[br];B[ap];W[aq];B[bs];W[cp];B[do];W[dq];B[ar]C[];W[as]C[Ko, white takes first. Well done ! -- Note that black has several local threats ; D2, E2... but ko anywayRIGHT]) (;W[cp];B[do] (;W[br];B[ap];W[aq];B[bs];W[dq];B[ar]C[];W[as]C[Ko, white takes first. Well done ! -- Note that black has several local threats ; D2, E2... but ko anywayRIGHT]) (;W[dq];B[br];W[ap];B[eq]))) (;W[cp];B[do] (;W[bq];B[cr] (;W[br];B[ap];W[aq];B[bs]) (;W[dq];B[br];W[ap];B[eq])) (;W[dq];B[bq];W[ap];B[aq];W[an];B[al]C[Black wins the semeai.])) (;W[br];B[bq];W[aq];B[cr])) (;B[bq];W[cp];B[cq];W[do];B[co];W[am]C[RIGHT]) (;B[cp];W[bq];B[cq];W[br];B[cr];W[bs]C[Black could play this way if F3 is weak.RIGHT])) (;W[cq];B[bo]) (;W[bo];B[bp]C[Too narrow space. If white A5, black A7.]) (;W[fi]C[You could get a ko.]))