(;AB[pr]AB[qq]AB[qp]AB[qo]AW[pq]AW[pp]AW[nq]AW[no]AW[np]AW[oo]AW[nn]AW[mn]AW[lo]AW[ln]AW[mp]AB[lp]AB[kp]AB[ko]AB[kn]AB[lm]AB[mm]AB[nm]AB[km]AB[lq]AW[po]AB[pn]AB[qn]AB[ol]AB[kr]C[Does white need to defend at A (this means for general defense, in order to make white undconditionally alive)? If not, play T for tenuki.]LB[oq:A]LB[kk:T]AB[pm]AB[om]AP[goproblems] (;W[kk];B[oq]C[Ok, please demonstrate how to live unconditionally then.] (;W[nr];B[or]) (;W[op];B[or]) (;W[qr];B[nr]) (;W[or];B[nr] (;W[op];B[os] (;W[mr];B[oq]C[Ko.]) (;W[qr];B[oq]C[Ko. A bad one for black, but a ko nevertheless.])) (;W[qr];B[os]) (;W[mr];B[os]) (;W[os];B[ps] (;W[op];B[ns];W[oq];B[mr];W[qr]C[Good.RIGHT]) (;W[mr];B[ns])) (;W[ns];B[os]) (;W[ps];B[os]))) (;W[oq]C[This is unnecessary (in keeping this group alive unconditionally).]))