(;AB[ar]AB[bs]AB[cq]AB[dr]AB[er]AB[es]AB[ds]AB[br]AW[cr]AW[fs]AW[fr]AW[fq]AW[eq]AW[dq]AW[dp]AW[cp]AW[bp]AW[ap]C[Black s move... (if you want to Tenuki, use T)FORCE]LB[cr:O]LB[fp:T]AP[goproblems] (;B[cs];W[bq]TR[bq]TR[dq]LB[cr:A]C[Since two of its corners are lost, A is not an eye.]) (;B[bq]LB[fp:T];W[cs]C[FORCE]LB[fp:T] (;B[dr]C[]LB[fp:T];W[ds]LB[fp:T]C[Ishi-no-shita, playing under the stones !] (;B[es]LB[fp:T]C[] (;W[er]C[CHOICE]LB[fp:T] (;B[cr];W[ds]C[So close ! You should study the Bamboo Joint formation, see how the solution achieves it.]) (;B[cs];W[ds]C[Almost ! This is Ko... You can t take back right away, you have to threaten somewhere else first. And if you can t find a Ko Threat big enough, White will fill in at a...]LB[es:a]) (;B[ds]C[Everything is under control :)RIGHT]LB[fp:T]) (;B[fp];W[cs]C[] (;B[cr];W[ds];B[es];W[ds]C[Nope, Tenuki was too soon.]) (;B[ds];W[cr]C[Damezumari, shortage of liberties.])))) (;B[er];W[es]C[You re on the right track, though.])) (;B[ds];W[dr]) (;B[aq]LB[fp:T];W[fp] (;B[dr];W[as]) (;B[ds];W[as])) (;B[as]LB[fp:T];W[fp] (;B[dr];W[aq]) (;B[ds];W[aq])) (;B[er];W[dr]) (;B[es];W[dr]) (;B[fp];W[dr])) (;B[aq]LB[fp:T];W[fp]C[If the liberty at A3 disappears, then Black can t be saved any more.FORCE]) (;B[as]LB[fp:T];W[fp]C[Don t gouge your own eye out...]) (;B[fp];W[bq]C[Black could actually have lived.]))