This is a position where white can try an abusive invasion, from the last Tsumego book by Motoki Noguchi (in french). In the book black stones are shifted to the left, and white die in gote. Here he can die in sente ^^
(;TR[dp]AW[cn]AB[cp]AB[ep]AB[gq]AW[ck]AB[jq]C[White just played at A. Please play a few moves as indicated.FORCE]AW[dq]LB[dq:A]AP[goproblems];B[dp];W[fr]TR[gr]C[FORCE];B[gr];W[fq]TR[fp]C[FORCE];B[fp];W[cq]C[Now kill all marked stones unconditionally. Let me know if you find something wrong.]MA[cq]MA[dq]MA[fq]MA[fr]
(;B[bq];W[br]
(;B[bp]
(;W[ar]C[CHOICE]
(;B[ds];W[es]
(;B[er]
(;W[fs]C[]
(;B[eq]C[Well done.RIGHT])
(;B[gs];W[eq];B[cr]C[RIGHT])
(;B[cr];W[eq];B[gs]C[RIGHT])))
(;B[eq];W[dr];B[cs];W[er];B[bs]C[RIGHT])
(;B[dr];W[eq]
(;B[cr];W[bs];B[aq]C[RIGHT])
(;B[er];W[cr];B[fs];W[cs]))
(;B[cr];W[dr];B[eq];W[cs])
(;B[cs];W[eq];B[bs];W[dr]))
(;B[fs];W[ds];B[cs];W[cr]
(;B[bs];W[er]C[])
(;B[er];W[eq];B[bs];W[dr]C[]))
(;B[eq];W[er];B[fs];W[ds]C[])
(;B[er];W[eq];B[fs];W[dr];B[ds];W[es]C[Ko])
(;B[es];W[er];B[fs];W[ds]C[])
(;B[dr];W[cr]
(;B[fs];W[er]C[])
(;B[er];W[eq];B[fs];W[ds]C[]))
(;B[cs];W[cr]
(;B[er];W[eq];B[fs];W[dr]C[])
(;B[ds];W[fs];B[eq];W[er]C[Seki])))
(;W[dr]
(;B[fs];W[es]
(;B[cs]
(;W[eq];B[bs];W[ar];B[cr]C[Nice damezumari. White cannot get an eye around H1 after G1, A3.RIGHT]))
(;B[eq]
(;W[cs];B[er];W[ar];B[ds]C[Ko.])))
(;B[ar];W[cs]TR[cr]TR[ds]C[Two eyes (at least by ko).])
(;B[eq];W[er];B[cs];W[ar];B[bs];W[fs]C[Miai seki - life.]MA[cr]MA[ds])
(;B[cs]C[Also possible - but the hane is more direct.RIGHT]))
(;W[cs];B[dr]MA[ar]MA[eq]C[RIGHT])
(;W[cr];B[er]MA[ar]MA[eq]C[RIGHT])
(;W[eq];B[ar]MA[cr]MA[fs]C[RIGHT])
(;W[er];B[ar]MA[cr]MA[ds]C[RIGHT])
(;W[es];B[dr]MA[eq]MA[ar]C[RIGHT])
(;W[bs];B[ds]MA[fs]MA[eq]MA[ar]C[RIGHT])
(;W[ds];B[eq];W[er];B[cr];W[dr];B[ar]C[RIGHT]))
(;B[aq];W[ar];B[bp];W[ds]C[])
(;B[ap]C[NOTTHIS])
(;B[bo]C[NOTTHIS]))
(;B[er];W[bp];B[bo];W[bq];B[co];W[eq];B[fs];W[dr]C[])
(;B[bp];W[bq]C[Thanks to c6 (and even without c6 ?) this shape should be alive. One example follows.];B[fs];W[ap];B[bo];W[er];B[bs];W[cr]
(;B[ds];W[es];B[eq];W[dr];B[cs]
(;W[ar]C[Seki.]))
(;B[es];W[ds];B[gs];W[eq];B[cs]C[Ko.])))