(;GM[1]FF[4]CA[UTF-8]AP[CGoban:3]ST[2]
RU[Japanese]SZ[19]KM[0.00]
PW[me]PB[also me]AW[ea][ra][eb][ob][pb][qb][bc][cc][dc][mc][nc][ld][od][qd][sd][qe][se][qf][qg][ph][rh][ri][cm][em][bn][cn][fn][ho][dq][eq][hq][qq][br][cr][dr][er][hr][nr][or][pr][qr][rr][es]AB[bb][cb][db][fb][nb][rb][oc][pc][qc][rc][rd][re][rf][rg][sh][bl][cl][dl][bm][qo][cp][dp][ep][fp][qp][cq][fq][mq][nq][oq][pq][rq][fr][mr][ds][fs]LB[ed:1][nf:4][gl:3][oo:2]C[Cho Chickun's encyclopedia of life and death: Volume 3

Problems 1-4

Black to play

I will try to figure them out in my head before putting any variations on the board (which is something I do too much when reviewing games I thinks...)]
(;B[ec]
;W[fc]
;B[ed]
;W[gb]
;B[da]
;W[fa]
(;B[ce]
;W[be]
;B[bd]
;W[cd]
;B[ac]
;W[ad]
;B[ab]
;W[de]
;B[cf]
;W[dd]
;B[ba]C[Seems like a pretty crude variation, black can do better])
(;B[ab]
(;W[ba]
;B[bd]
;W[cd]
;B[ce]
;W[be]
;B[ac]
;W[ad]
;B[dd]
;W[bd]
;B[bf]C[so white cannot play B19 without protecting on the outside first])
(;W[ce]
;B[ba]C[probably the best for black, still aji on the outside for black epending on the situation of course])))
(;B[oa]
(;W[mb]
;B[qa]
;W[na]
(;B[sa]
;W[sc]
;B[sg]C[Seki, not bad for black])
(;B[sc]
;W[sa]
;B[sb]
;W[ra]C[not good enough black just dies]))
(;W[qa]C[white's best refutation, black is dead]
;B[sb]))
(;B[sr]
;W[rp]
;B[sp]
(;W[sq])
(;W[ro]
;B[rn]
;W[sq]C[ko seems to be the only way]))
(;B[ap]C[One of these four I found hardest, actually it's not so tricky once you find this move though!]
(;W[ao]
(;B[ar]
;W[bp]
;B[bq]
;W[aq]C[ko])
(;B[bo]
;W[an]
;B[ar]
;W[bq]
;B[bp]
;W[aq]
;B[bs]
;W[as]C[ko again]))
(;W[aq]
(;B[an]
;W[bp]
;B[ao]
;W[bo]
;B[am]
;W[bq]C[black is dead])
(;B[ar]
(;W[bq]
;B[bp]
(;W[as]
;B[an])
(;W[an]
;B[bs]
;W[as]))
(;W[as]
;B[bq]
;W[ar]
;B[cs]
;W[bs]
;B[cs]
;W[ds]
;B[cs]))))
(;B[qa]
;W[pa]
;B[sa]
;W[sb]
;B[sc]
;W[mb]
;B[sa]
;W[na]
;B[qa]C[ko, the only way for black]))