(;AW[ar]AW[as]AW[br]AW[dq]AW[er]AW[fr]AW[gr]AB[ds]AB[es]AB[hs]AB[is]AB[js]AB[kr]AB[lr]AB[ls]AB[eq]AB[fq]AB[gq]AW[hq]AW[hr]AB[hp]AW[iq]AW[jq]AW[kq]AW[lq]AB[mq]AB[nq]AB[nr]AW[mr]AW[ns]AB[lp]AB[kp]AB[ip]AB[jp]AB[dp]AB[cp]AB[bo]AB[cn]AP[goproblems]
(;W[dr]
(;B[cs]C[]
(;W[gs]
(;B[cr]C[];W[cq];B[bq]
(;W[aq]
(;B[bp]C[];W[fs];B[ap];W[bs]
(;B[ds]C[]
(;W[cs];B[cr];W[br]
(;B[cs]C[CHOICE]
(;W[bs];B[ar];W[es];B[cs]
(;W[jr]
(;B[aq];W[ir];B[as]
(;W[ks];B[js]
(;W[is];B[cr];W[ks]C[Hoping to deceive white, black refused his best ko opportunity; he now pays the price fighting a direct koRIGHT])
(;W[cr];B[is]))
(;W[cr];B[ds]))
(;B[cr]C[This path is for informational purposes only; the computer will not play it];W[ds];B[cr];W[cs];B[aq];W[ir]C[RIGHT]))
(;W[ir];B[jr]C[Oops...]))
(;W[ar];B[bs];W[es];B[ms];W[as];B[cs]))
(;B[bs]C[CHOICE]
(;W[cs]C[];B[ar]
(;W[as]C[]
(;B[nn]C[Well done! You live if you survive what is almost a 1-step ko! To illustrate this, black starts with a ko threat which you choose to ignore. Please play at ARIGHT]LB[aq:A];W[aq]C[];B[mn]C[Black cashes in and white is not yet safe. You can only leave this situation if you have superior ko threats. Please play at A]LB[ar:A];W[ar]C[];B[ln]C[FINISHED. Black takes sente as is typical for a 1-step ko.RIGHT])
(;B[aq]C[This path is for informational purposes only; it will not be played by the computer];W[es];B[bs]C[This is a 'black take first' ko but it is not as good as starting it one move earlier which is almost equal to a 1-step koRIGHT]))
(;W[es]C[No point in being defensive yet. Your chances of winning the ko are the same but you'll lose a few points in the corner.]))
(;W[ar];B[cs]C[FORCE];W[es];B[ms];W[as];B[cs])))
(;W[jr];B[cs];W[ir];B[cr];W[ks];B[js])
(;W[ir];B[jr])
(;W[cr];B[jr]))
(;B[cs]C[This path is for informational purposes only; the computer will not play it];W[ds];B[cr];W[br]C[RIGHT]))
(;B[ap]C[This path is for informational purposes only; the computer will not play it.];W[bp]C[White will play the ko; he won't get anything better in the main lineRIGHT]))
(;W[fs];B[aq];W[bs];B[ds]
(;W[cs];B[cr];W[br];B[cs];W[bs];B[ar];W[es];B[cs];W[jr];B[as];W[ir];B[cr];W[ks];B[js];W[is];B[ms]C[Not quite there])
(;W[jr];B[cs];W[ir];B[cr];W[ks];B[js])
(;W[es];B[cs])))
(;B[jr];W[cr]C[SekiRIGHT]))
(;W[fs];B[cq])
(;W[cq];B[gs];W[fs];B[bq]
(;W[jr];B[ms]
(;W[cr];B[os]C[Black escapes in time with his bottom stones])
(;W[ir];B[cr]))
(;W[aq];B[bp];W[jr];B[ms]
(;W[cr];B[os]C[Black escapes in time with his bottom stones])
(;W[ir];B[cr])))
(;W[cr];B[gs]
(;W[jr];B[os];W[fs];B[ms])
(;W[fs];B[os];W[jr];B[ms])))
(;B[gs]C[This path is for informational purposes only; it will not be played by the computer]
(;W[fs];B[cs];W[jr]
(;B[ms];W[ir];B[cr];W[ks]C[And black loses 4 more stones on the left or the rightRIGHT])
(;B[cr];W[cq];B[bq];W[bs]C[RIGHT]))
(;W[cs]C[This would be an error!];B[fs];W[jr];B[cr];W[cq];B[bq];W[aq];B[bp];W[cr];B[ap]C[White cannot approach];W[ir];B[bs]))
(;B[cq]C[This path is for informational purposes only; it will not be played by the computer];W[cr]
(;B[cs];W[gs];B[ms]C[SekiRIGHT])
(;B[gs];W[cs];B[fs];W[jr];B[bq];W[ir]C[Just in time!RIGHT])))
(;W[cq];B[cs]
(;W[bp];B[dr]
(;W[ap];B[gs]C[Over and out!])
(;W[cr];B[ap]))
(;W[dr];B[gs];W[fs];B[bq]
(;W[jr];B[ms]
(;W[cr];B[os]C[Black escapes in time with his bottom stones])
(;W[ir];B[cr]))
(;W[aq];B[bp];W[jr];B[ms]
(;W[cr];B[os]C[Black escapes in time with his bottom stones])
(;W[ir];B[cr])))
(;W[cr];B[gs];W[fs]C[Easy for black even playing tenuki])
(;W[jr];B[dr];W[cr]C[Black can play tenuki here])
(;W[aq];B[bp]C[The last exchange won't help; navigate the variations without it]))
(;W[cs];B[cq];W[dr];B[cr])
(;W[cr];B[dr];W[cq];B[cs];W[bp];B[ap])
(;W[jr];B[cq]))