invalid problem set
Problem 2001
Created 2003-03-12
Source Some spare time
Rating
Difficulty 9 dan
Average Solve Time 223 secs
User Attempts
20 / 1531
Solve Ratio Rating 6 dan
rating history
I intended to make this problem a little easier than 1995 but I may have failed - they do say big groups don't die. Kill all the marked stones unconditionally - ko is not enough.
(
;
FF[4]
GM[1]
SZ[19]
AP[Jago:Version 4.18]
AW[sq][gr][rp][qq][qr][rl][qk][rj][qi][rh][qg][pj][oj][nj][mk][ll][ln][kn][jn][kj][jk][ik][hk][ji][jh][nh][mg][lf][le][kc][kb][jd][je][kf][mc][nc][nb][od][ne][he][hf][hg][gg][ge][ff][ef][df][fc][db][ce][be][fk][fl][fj][ei][fh][ek][dk][dj][dl][em][dm][cl][bk][ap][bp][bo][cp][hq][iq][io][ho][hn][ma][fb][hb][fa][bc][ae][dq][ka][cb][ba][gn][eo][er][cr][fr][gp][do][pe][qe][qd][sh][ld][oh][rm][sg][hl][ds][il][gd][ha]
AB[ao][di][is][bm][bn][cn][dn][en][fn][fm][gj][gk][gl][hm][im][in][jm][jo][jp][jq][jr][ko][lo][no][nn][nm][nl][nk][oq][pq][qp][qo][ro][ql][pl][pk][pi][ph][qh][pg][qf][rf][ni][li][lh][kg][jg][jf][ig][ih][hh][ij][if][ie][hd][id][jc][lc][nf][pd][oc][ob][qc][lb][ic][ib][ia][gb][cj][ci][bi][bh][af][bf][cf][cg][dg][eg][fg][dh][de][dd][dc][eb][fp][dp][gm][go][eq][fq][pc][rc][ra][sb][og][qn][si][bq][br][oa][gc]
GN[temp]
TR[fn][ig][li][bm][bn][cn][dn][en][fm][gm][hm][im][jm][in][gl][gk][gj][ij][hh][ih][lh][kg][jg][jf][if][ie][id][hd][ic][jc][ib][ia]
C[Kill all the marked stones. Hint: White has a cutting point near the centre that needs urgent defense, which connection to choose?]
(
;
W[lj]
;
B[mi]
(
;
W[mj]
;
B[oi]
(
;
W[pf]
;
B[rg]
(
;
W[re]
;
B[sf]
;
W[ri]
;
B[se]
;
W[sd]
;
B[qg]
;
W[rd]
;
B[oe]
;
W[of]
;
B[sc]
;
W[oe]
;
B[me]
;
W[nd]
;
B[ng]
(
;
W[lg]
;
B[gh]
C[Please choose between 'a', 'b', 'c', 'd', 'e' and 'f'.]
LB[fi:a][ii:b][ec:c][fo:d][kh:e][kl:f]
(
;
W[ec]
;
B[gi]
;
W[fi]
;
B[fo]
(
;
W[ep]
;
B[gq]
(
;
W[hr]
;
B[kl]
(
;
W[lm]
;
B[jj]
(
;
W[ki]
;
B[kk]
(
;
W[ii]
;
B[hj]
(
;
W[bl]
C[RIGHT]
)
(
;
W[ck]
C[RIGHT]
)
(
;
W[bj]
C[RIGHT]
)
(
;
W[aj]
C[RIGHT]
)
(
;
W[ak]
C[RIGHT]
)
(
;
W[al]
C[RIGHT]
)
(
;
W[an]
C[RIGHT]
)
)
(
;
W[bl]
;
B[ii]
)
)
(
;
W[kk]
;
B[ki]
(
;
W[mh]
;
B[bl]
;
W[ck]
;
B[al]
)
(
;
W[hj]
;
B[ii]
(
;
W[mh]
;
B[bl]
;
W[ck]
;
B[al]
)
(
;
W[bl]
;
B[mh]
)
)
(
;
W[bl]
;
B[mh]
)
)
(
;
W[ii]
;
B[hj]
(
;
W[ki]
;
B[kk]
(
;
W[bl]
C[RIGHT]
)
(
;
W[bj]
C[RIGHT]
)
(
;
W[ck]
C[RIGHT]
)
(
;
W[aj]
C[RIGHT]
)
(
;
W[ak]
C[RIGHT]
)
(
;
W[al]
C[RIGHT]
)
(
;
W[an]
C[RIGHT]
)
)
(
;
W[kk]
;
B[ki]
(
;
W[mh]
;
B[bl]
;
W[ck]
;
B[al]
)
(
;
W[bl]
;
B[mh]
)
)
(
;
W[bl]
;
B[ki]
(
;
W[mh]
;
B[kk]
)
(
;
W[kk]
;
B[mh]
)
)
)
(
;
W[hj]
;
B[ii]
(
;
W[ki]
;
B[kk]
)
(
;
W[kk]
;
B[ki]
(
;
W[mh]
;
B[bl]
;
W[ck]
;
B[al]
)
(
;
W[bl]
;
B[mh]
)
)
(
;
W[bl]
;
B[kk]
)
)
)
(
;
W[km]
;
B[lm]
;
W[mm]
;
B[mn]
;
W[lm]
;
B[jj]
(
;
W[ki]
;
B[kk]
(
;
W[ii]
;
B[hj]
(
;
W[bl]
C[RIGHT]
)
(
;
W[ck]
C[RIGHT]
)
(
;
W[bj]
C[RIGHT]
)
(
;
W[aj]
C[RIGHT]
)
(
;
W[ak]
C[RIGHT]
)
(
;
W[al]
C[RIGHT]
)
(
;
W[an]
C[RIGHT]
)
(
;
W[lk]
;
B[jl]
;
W[ik]
;
B[bl]
;
W[ck]
;
B[al]
)
)
(
;
W[bl]
;
B[ii]
)
(
;
W[lk]
;
B[jl]
(
;
W[ii]
;
B[hj]
;
W[ik]
;
B[bl]
;
W[ck]
;
B[al]
)
(
;
W[bl]
;
B[ii]
)
)
)
(
;
W[kk]
;
B[ki]
(
;
W[mh]
;
B[bl]
;
W[ck]
;
B[al]
)
(
;
W[bl]
;
B[mh]
)
(
;
W[hj]
;
B[ii]
(
;
W[mh]
;
B[bl]
;
W[ck]
;
B[al]
)
(
;
W[bl]
;
B[mh]
)
)
)
(
;
W[bl]
;
B[ki]
(
;
W[kk]
;
B[mh]
)
(
;
W[hj]
;
B[ii]
(
;
W[kk]
;
B[mh]
)
(
;
W[mh]
;
B[kk]
)
)
(
;
W[mh]
;
B[kk]
)
)
(
;
W[hj]
;
B[ii]
(
;
W[kk]
;
B[ki]
(
;
W[mh]
;
B[bl]
;
W[ck]
;
B[al]
)
(
;
W[bl]
;
B[mh]
)
)
(
;
W[ki]
;
B[kk]
)
(
;
W[bl]
;
B[kk]
)
)
(
;
W[ii]
;
B[hj]
(
;
W[ki]
;
B[kk]
(
;
W[bl]
C[RIGHT]
)
(
;
W[ck]
C[RIGHT]
)
(
;
W[bj]
C[RIGHT]
)
(
;
W[aj]
C[RIGHT]
)
(
;
W[ak]
C[RIGHT]
)
(
;
W[al]
C[RIGHT]
)
(
;
W[an]
C[RIGHT]
)
)
(
;
W[kk]
;
B[ki]
(
;
W[mh]
;
B[bl]
;
W[ck]
;
B[al]
)
(
;
W[bl]
;
B[mh]
)
)
(
;
W[bl]
;
B[ki]
(
;
W[kk]
;
B[mh]
)
(
;
W[mh]
;
B[kk]
)
)
)
)
(
;
W[mm]
;
B[jj]
(
;
W[ki]
;
B[kk]
(
;
W[ii]
;
B[hj]
(
;
W[bl]
C[RIGHT]
)
(
;
W[bj]
C[RIGHT]
)
(
;
W[ck]
C[RIGHT]
)
(
;
W[aj]
C[RIGHT]
)
(
;
W[ak]
C[RIGHT]
)
(
;
W[al]
C[RIGHT]
)
(
;
W[an]
C[RIGHT]
)
)
(
;
W[bl]
;
B[ii]
)
)
(
;
W[kk]
;
B[ki]
(
;
W[mh]
;
B[bl]
;
W[ck]
;
B[al]
)
(
;
W[bl]
;
B[mh]
)
(
;
W[hj]
;
B[ii]
(
;
W[mh]
;
B[bl]
;
W[ck]
;
B[al]
)
(
;
W[bl]
;
B[mh]
)
)
)
(
;
W[bl]
;
B[ki]
(
;
W[kk]
;
B[mh]
)
(
;
W[mh]
;
B[kk]
)
(
;
W[hj]
;
B[ii]
(
;
W[kk]
;
B[mh]
)
(
;
W[mh]
;
B[kk]
)
)
)
(
;
W[ii]
;
B[hj]
(
;
W[ki]
;
B[kk]
(
;
W[bl]
C[RIGHT]
)
(
;
W[ck]
C[RIGHT]
)
(
;
W[bj]
C[RIGHT]
)
(
;
W[aj]
C[RIGHT]
)
(
;
W[ak]
C[RIGHT]
)
(
;
W[al]
C[RIGHT]
)
(
;
W[an]
C[RIGHT]
)
)
(
;
W[kk]
;
B[ki]
(
;
W[mh]
;
B[bl]
;
W[ck]
;
B[al]
)
(
;
W[bl]
;
B[mh]
)
)
(
;
W[bl]
;
B[ki]
(
;
W[kk]
;
B[mh]
)
(
;
W[mh]
;
B[kk]
)
)
)
(
;
W[hj]
;
B[ii]
(
;
W[kk]
;
B[ki]
(
;
W[mh]
;
B[bl]
;
W[ck]
;
B[al]
)
(
;
W[bl]
;
B[mh]
)
)
(
;
W[ki]
;
B[kk]
)
(
;
W[bl]
;
B[kk]
)
)
)
(
;
W[mn]
;
B[lm]
(
;
W[mm]
;
B[ml]
;
W[km]
;
B[mo]
)
(
;
W[km]
;
B[mm]
)
)
(
;
W[ml]
;
B[lm]
;
W[mm]
;
B[mn]
)
(
;
W[kk]
;
B[lm]
)
(
;
W[jj]
;
B[lm]
)
)
(
;
W[hp]
;
B[hr]
)
(
;
W[ir]
;
B[ip]
)
(
;
W[hs]
;
B[ip]
;
W[hp]
;
B[hr]
)
(
;
W[ip]
;
B[hr]
)
)
(
;
W[co]
;
B[cq]
(
;
W[ep]
;
B[an]
LB[bs:a]
C[please stop black from playing atari by playing at 'a'.]
;
W[bs]
;
B[bl]
;
W[ck]
;
B[al]
(
;
W[ak]
;
B[kh]
;
W[mh]
;
B[jj]
;
W[ki]
;
B[kl]
C[black makes a second eye (L9) or connects out (M7)]
)
(
;
W[bj]
;
B[kh]
;
W[mh]
;
B[jj]
;
W[ki]
;
B[kl]
C[black makes a second eye (L9) or connects out (M7)]
)
(
;
W[aj]
;
B[kh]
;
W[mh]
;
B[jj]
;
W[ki]
;
B[kl]
C[black makes a second eye (L9) or connects out (M7)]
)
)
(
;
W[an]
;
B[dr]
C[an all-dominating ko, black will ignore any threat]
)
)
(
;
W[an]
;
B[co]
(
;
W[cq]
;
B[kh]
;
W[mh]
;
B[jj]
;
W[ki]
;
B[kl]
C[black makes a second eye (L9) or connects out (M7)]
)
(
;
W[jj]
;
B[cq]
C[ko, black will play A3 if white connects]
)
)
(
;
W[cq]
;
B[co]
(
;
W[jj]
;
B[bl]
;
W[ck]
;
B[al]
)
(
;
W[bl]
;
B[kh]
;
W[mh]
;
B[jj]
;
W[ki]
;
B[kl]
C[black makes a second eye (L9) or connects out (M7)]
)
)
(
;
W[gq]
;
B[co]
(
;
W[cq]
C[black is alive (B8 or K10 next)]
)
(
;
W[an]
;
B[kh]
;
W[mh]
;
B[jj]
;
W[ki]
;
B[kl]
C[black makes a second eye (L9) or connects out (M7)]
)
)
)
(
;
W[fi]
;
B[fd]
(
;
W[ed]
;
B[ec]
(
;
W[ee]
;
B[ea]
;
W[fe]
;
B[hc]
C[white loses]
)
(
;
W[ea]
;
B[ee]
)
(
;
W[ga]
;
B[hc]
)
(
;
W[fe]
;
B[ea]
C[please play at 'a']
LB[da:a]
;
W[da]
;
B[hc]
LB[cc:a]
C[please play at 'a']
;
W[cc]
;
B[ga]
;
W[fd]
;
B[kh]
;
W[mh]
;
B[bl]
;
W[ck]
;
B[al]
)
)
(
;
W[fe]
;
B[ed]
)
(
;
W[ga]
;
B[hc]
(
;
W[ed]
;
B[ec]
)
(
;
W[fe]
;
B[ec]
)
)
)
(
;
W[ii]
;
B[gi]
;
W[fi]
;
B[fd]
(
;
W[ed]
;
B[ec]
(
;
W[ee]
;
B[ea]
;
W[fe]
;
B[hc]
C[white loses]
)
(
;
W[ea]
;
B[ee]
)
(
;
W[ga]
;
B[hc]
)
(
;
W[fe]
;
B[ea]
C[please play at 'a']
LB[da:a]
;
W[da]
;
B[hc]
LB[cc:a]
C[please play at 'a']
;
W[cc]
;
B[ga]
;
W[fd]
;
B[kh]
;
W[mh]
;
B[bl]
;
W[ck]
;
B[al]
)
)
(
;
W[fe]
;
B[ed]
)
(
;
W[ga]
;
B[hc]
(
;
W[ed]
;
B[ec]
)
(
;
W[fe]
;
B[ec]
)
)
)
(
;
W[fo]
;
B[gi]
;
W[fi]
;
B[fd]
(
;
W[ga]
;
B[hc]
(
;
W[ed]
;
B[ec]
)
(
;
W[fe]
;
B[ec]
)
)
(
;
W[fe]
;
B[ed]
)
(
;
W[ed]
;
B[ec]
(
;
W[ee]
;
B[ea]
;
W[fe]
;
B[hc]
C[white loses]
)
(
;
W[ea]
;
B[ee]
)
(
;
W[ga]
;
B[hc]
)
(
;
W[fe]
;
B[ea]
C[please play at 'a']
LB[da:a]
;
W[da]
;
B[hc]
LB[cc:a]
C[please play at 'a']
;
W[cc]
;
B[ga]
;
W[fd]
;
B[kh]
;
W[mh]
;
B[bl]
;
W[ck]
;
B[al]
)
)
)
(
;
W[kh]
;
B[fd]
(
;
W[ga]
;
B[hc]
(
;
W[ed]
;
B[ec]
)
(
;
W[fe]
;
B[ec]
)
)
(
;
W[fe]
;
B[ed]
)
(
;
W[ed]
;
B[ec]
(
;
W[ea]
;
B[ee]
)
(
;
W[ee]
;
B[ea]
;
W[fe]
;
B[hc]
C[white loses]
)
(
;
W[ga]
;
B[hc]
)
(
;
W[fe]
;
B[ea]
C[please play at 'a']
LB[da:a]
;
W[da]
;
B[hc]
C[please play at 'a']
LB[cc:a]
;
W[cc]
;
B[ga]
;
W[fd]
;
B[bl]
;
W[ck]
;
B[al]
)
)
)
(
;
W[kl]
;
B[fd]
(
;
W[ga]
;
B[hc]
(
;
W[ed]
;
B[ec]
)
(
;
W[fe]
;
B[ec]
)
)
(
;
W[fe]
;
B[ed]
)
(
;
W[ed]
;
B[ec]
(
;
W[ee]
;
B[ea]
;
W[fe]
;
B[hc]
C[white loses]
)
(
;
W[ea]
;
B[ee]
)
(
;
W[ga]
;
B[hc]
)
(
;
W[fe]
;
B[ea]
C[please play at 'a']
LB[da:a]
;
W[da]
;
B[hc]
C[please play at 'a']
LB[cc:a]
;
W[cc]
;
B[ga]
;
W[fd]
;
B[kh]
;
W[mh]
;
B[bl]
;
W[ck]
;
B[al]
)
)
)
)
(
;
W[mh]
;
B[mf]
;
W[lg]
;
B[kd]
(
;
W[ke]
;
B[md]
;
W[kd]
;
B[na]
)
(
;
W[kh]
;
B[ke]
;
W[md]
;
B[hj]
(
;
W[bl]
;
B[ii]
(
;
W[gi]
;
B[jj]
;
W[ki]
;
B[kk]
)
(
;
W[jj]
;
B[gi]
)
)
(
;
W[jj]
;
B[bl]
;
W[ck]
;
B[al]
)
)
(
;
W[md]
;
B[ke]
;
W[kh]
;
B[hj]
(
;
W[jj]
;
B[bl]
;
W[ck]
;
B[al]
)
(
;
W[bl]
;
B[ii]
(
;
W[gi]
;
B[jj]
;
W[ki]
;
B[kk]
)
(
;
W[jj]
;
B[gi]
)
)
(
;
W[gi]
;
B[bl]
;
W[ck]
;
B[al]
)
)
)
(
;
W[mf]
C[black has sente and has 3 places where he can make eyes in gote (N12, B8 and in the centre - see variations)]
)
)
(
;
W[se]
;
B[sf]
;
W[ri]
;
B[re]
)
(
;
W[rd]
;
B[sf]
;
W[ri]
;
B[sd]
)
(
;
W[sd]
;
B[sf]
;
W[ri]
;
B[rd]
;
W[re]
;
B[oe]
(
;
W[of]
;
B[sc]
)
(
;
W[se]
;
B[of]
)
)
)
(
;
W[re]
;
B[pf]
(
;
W[sf]
;
B[gh]
C[The extra gote eye on the right is sufficient for black to live, please compare to the correct path.]
)
(
;
W[oe]
;
B[sf]
C[The sente eye on the right (white must also prevent connection to the corner) means black lives easily, please compare to the correct path.]
)
(
;
W[rg]
;
B[sf]
(
;
W[ri]
;
B[se]
)
(
;
W[se]
;
B[ri]
C[White doesn't have time to throw in.]
)
)
)
(
;
W[rg]
;
B[sf]
(
;
W[ri]
;
B[pf]
C[black is connected to the corner]
)
(
;
W[re]
;
B[ri]
C[black can connect to the corner or play S13]
)
(
;
W[sd]
;
B[ri]
C[black can connect to the corner or play S13]
)
)
(
;
W[rd]
;
B[pf]
(
;
W[rg]
;
B[sd]
;
W[se]
;
B[re]
;
W[sc]
;
B[sf]
)
(
;
W[sf]
;
B[gh]
C[The gote eye on the right is sufficient for black to live, please compare to the correct path]
)
(
;
W[se]
;
B[sf]
(
;
W[re]
;
B[rg]
;
W[ri]
;
B[gh]
C[black lives easily after getting an eye in sente, please compare to the correct path]
)
(
;
W[ri]
;
B[sd]
C[black is connected to the corner]
)
(
;
W[oe]
;
B[rg]
;
W[ri]
;
B[gh]
C[black lives easily after getting an eye in sente, please compare to the correct path]
)
)
(
;
W[oe]
;
B[sf]
(
;
W[sd]
;
B[rg]
;
W[ri]
;
B[gh]
C[black lives easily after getting an eye in sente, please compare to the correct path]
)
(
;
W[ri]
;
B[sd]
)
)
)
(
;
W[ri]
;
B[pf]
(
;
W[rg]
;
B[re]
)
(
;
W[re]
;
B[gh]
C[the extra gote eye on the right is sufficient for black to live, please compare to the correct path]
)
(
;
W[sd]
;
B[gh]
C[the extra gote eye on the right is sufficient for black to live, please compare to the correct path]
)
(
;
W[rd]
;
B[sd]
;
W[se]
;
B[re]
;
W[sc]
;
B[sf]
)
(
;
W[se]
;
B[re]
;
W[rd]
;
B[sd]
;
W[sc]
;
B[sf]
)
)
(
;
W[sd]
;
B[pf]
(
;
W[sf]
;
B[gh]
C[the extra gote eye on the right is sufficient for black to live, please compare to the correct path]
)
(
;
W[rg]
;
B[sf]
(
;
W[ri]
;
B[rd]
)
(
;
W[rd]
;
B[ri]
C[white doesn't have time to throw in]
)
)
(
;
W[ri]
;
B[gh]
C[the extra gote eye on the right is sufficient for black to live, please compare to the correct path]
)
)
(
;
W[se]
;
B[pf]
(
;
W[sf]
;
B[gh]
C[the extra gote eye on the right is sufficient for black to live, please compare to the correct path]
)
(
;
W[rg]
;
B[re]
;
W[rd]
;
B[sd]
;
W[sc]
;
B[sf]
)
)
)
(
;
W[oi]
;
B[mj]
;
W[hi]
;
B[gi]
;
W[gh]
;
B[ii]
;
W[hj]
;
B[ml]
;
W[lk]
;
B[jj]
;
W[ki]
;
B[kk]
;
W[kl]
;
B[jl]
;
W[kk]
;
B[lm]
)
(
;
W[hi]
;
B[gi]
(
;
W[gh]
;
B[mj]
C[white is dead in the centre]
)
(
;
W[mj]
;
B[gh]
;
W[fi]
;
B[fd]
(
;
W[ga]
;
B[hc]
(
;
W[ed]
;
B[ec]
)
(
;
W[fe]
;
B[ec]
)
)
(
;
W[fe]
;
B[ed]
)
(
;
W[ed]
;
B[ec]
(
;
W[ga]
;
B[hc]
)
(
;
W[ea]
;
B[ee]
)
(
;
W[ee]
;
B[ea]
;
W[fe]
;
B[hc]
C[white loses]
)
(
;
W[fe]
;
B[ea]
C[please play at 'a']
LB[da:a]
;
W[da]
;
B[hc]
C[please play at 'a']
LB[cc:a]
;
W[cc]
;
B[ga]
;
W[fd]
;
B[hj]
;
W[ii]
;
B[jj]
)
)
)
)
(
;
W[gh]
;
B[mj]
C[white is dead in the centre]
)
)
(
;
W[mj]
;
B[lm]
;
W[km]
;
B[kl]
;
W[mm]
;
B[mn]
;
W[lm]
;
B[lk]
;
W[ml]
;
B[lj]
)
(
;
W[mi]
;
B[lm]
;
W[km]
;
B[kl]
;
W[mm]
;
B[mn]
;
W[lm]
;
B[lk]
)
(
;
W[fo]
;
B[mj]
C[The stones in the lower left were in no immediate danger, please see the correct path for how white can deflect black's attack here.]
)
(
;
W[hi]
;
B[gi]
(
;
W[gh]
;
B[mj]
C[white dies in the centre]
)
(
;
W[lj]
;
B[mi]
;
W[mj]
;
B[gh]
;
W[fi]
;
B[fd]
(
;
W[ga]
;
B[hc]
(
;
W[ed]
;
B[ec]
)
(
;
W[fe]
;
B[ec]
)
)
(
;
W[fe]
;
B[ed]
)
(
;
W[ed]
;
B[ec]
(
;
W[ee]
;
B[ea]
;
W[fe]
;
B[hc]
C[white loses]
)
(
;
W[ea]
;
B[ee]
)
(
;
W[ga]
;
B[hc]
)
(
;
W[fe]
;
B[ea]
C[please play at 'a']
LB[da:a]
;
W[da]
;
B[hc]
C[please play at 'a']
LB[cc:a]
;
W[cc]
;
B[ga]
;
W[fd]
;
B[hj]
;
W[ii]
;
B[jj]
)
)
)
)
(
;
W[fd]
;
B[mj]
C[white was in no immediate danger in the upper left]
)
(
;
W[gh]
;
B[mj]
C[both sides are cut but it is black who wins, G12 is not urgent since the white groups it connects are both strong (although there is aji at the top if black gets G12).]
)
)
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