(;GM[1]FF[4]CA[UTF-8]AP[CGoban:3]ST[2]
RU[Japanese]SZ[19]KM[0.00]
GN[ ]PW[White]PB[Black]AW[ca][cb][cc][ec][fc][gc][pc][cd][ed][pd][qd][de][ee][oe][qe][of][pf][qf][rg][oi][qi][qj][rj][rl][cm][dm][em][fm][gm][bn][hn][pn][qn][rn][ho][oo][cp][dp][hp][np][sp][bq][eq][fq][hq][nq][gr][nr][or][qr][rr][ps]AB[ba][bb][hb][pb][bc][ic][nc][oc][qc][rc][bd][dd][fd][hd][od][ce][fe][he][ne][cf][df][ef][nf][ng][og][pg][qg][qh][ri][fn][gn][bo][co][do][eo][go][qo][ro][bp][ep][fp][gp][pp][rp][gq][oq][pq][qq][rq][pr]LB[md:B][bg:C][bl:D][nn:A]C[Solutions - hints

A - Not so many moves to try here to make the 2nd eye

B - a two-move combination which both removes the eye and the connection at the same time

C - An example of playing a forcing move before the vital point to kill the group

D - All about using shortage of liberties to make a 2nd eye]FG[258:]PM[2]
(;B[rs]C[Problem A solution]
;W[qs]
;B[so]
;W[sq]
;B[sr]C[White needs to both connect the four stones
and play the throw in to stop black living.])
(;B[rf]C[Problem B solution]
;W[sf]
;B[sh]C[White's edge eye is now false.])
(;B[dc]C[Problem C solution]
;W[db]
;B[ea]C[Only one eye.])
(;B[fr]C[Problem D solution]
(;W[er]
;B[cq]
;W[dq]
;B[cr]
;W[br]
;B[bs]
;W[dr]
;B[cs]C[White cannot atari from either side without self-atari.])
(;W[dr]C[Variation]
;B[hr]
;W[ir]
;B[er]
;W[dq]
;B[gs]
;W[es]
;B[ar]
;W[aq]
;B[br]
;W[cr]
;B[ap]C[White runs out of liberties])))
