(;AB[br]AB[bs]AB[cq]AB[dq]AB[eq]AB[ds]AB[fq]AB[gr]AB[hq]AB[iq]AB[ir]AB[jp]AB[kp]AB[lp]AW[bq]AW[aq]AW[ar]AW[cp]AW[bp]AW[dp]AW[ep]AW[fp]AW[gp]AW[gq]AW[hp]AW[ip]AW[jq]AB[lr]AW[hr]AB[as]C[What can white do here?]AP[goproblems]
(;W[fr]
(;B[hs]
(;W[cr]
(;B[cs];W[es];B[dr]
(;W[gs]C[Ko for everything.RIGHT])
(;W[jr];B[gs]
(;W[js];B[is])
(;W[is];B[js];W[ks];B[is])))
(;B[er];W[cs];B[fs];W[dr];B[es]C[This is best for both.RIGHT]))
(;W[es]
(;B[er];W[cr];B[fs];W[cs]C[White can capture some stones. The E1 sacrifice is not necessary, it loses a couple of points.RIGHT])
(;B[cr];W[gs];B[hr];W[jr]C[RIGHT]))
(;W[er];B[dr])
(;W[jr];B[er]
(;W[fs];B[ap])
(;W[js];B[is])
(;W[is];B[js];W[ks];B[is]))
(;W[fs];B[er]))
(;B[gs]C[This is a mistake by black.]
(;W[jr];B[hs];W[js];B[fs];W[is]C[white breaks through without ko.RIGHT])
(;W[fs];B[hs];W[jr];B[kr])
(;W[is];B[hs];W[jr];B[js];W[ks];B[fs];W[is]C[only ko])))
(;W[cr]
(;B[cs]
(;W[fr]
(;B[hs];W[es];B[dr]
(;W[gs]C[Ko for everything.RIGHT])
(;W[jr];B[gs]
(;W[js];B[is])
(;W[is];B[js];W[ks];B[is])))
(;B[gs]C[This variation is for reference only, as requested by 'bones'];W[jr];B[hs];W[js];B[er];W[is]C[RIGHT]))
(;W[es];B[dr]
(;W[fr];B[gs]
(;W[jr];B[hs]
(;W[js];B[is])
(;W[is];B[js];W[ks];B[is]))
(;W[is];B[jr]))
(;W[gs];B[fr])))
(;B[fr];W[dr];B[es];W[cs];B[er]C[This is best for both.RIGHT]))
(;W[jr];B[hs]
(;W[fr];B[er]
(;W[fs];B[ap])
(;W[js];B[is])
(;W[is];B[js];W[ks];B[is]))
(;W[js];B[fr]))
(;W[hs];B[gs]
(;W[fr];B[is]
(;W[cr];B[cs];W[es];B[dr])
(;W[es];B[cr]))
(;W[jr];B[is])
(;W[cr];B[cs]
(;W[fr];B[is];W[es];B[dr])
(;W[es];B[dr];W[fr];B[is])))
(;W[is];B[hs]
(;W[fr];B[fs];W[jr];B[js];W[ks];B[is])
(;W[jr];B[js];W[ks];B[is]))
(;W[gs];B[fr]
(;W[is];B[jr])
(;W[jr];B[hs]))
(;W[es];B[cr];W[fr];B[gs]
(;W[jr];B[is])
(;W[is];B[jr]))
(;W[cs];B[cr]))