(;
GM[1]FF[4]VW[]AP[Many Faces of Go:11.0]
SZ[19]
HA[0]
ST[0]
PC["The Most Difficult Problem Ever"]
KM[0.0]
RU[Japanese]
SO[Created by Inoue Dosetsu Inseki (1646 - 1719)]
US[Compiled by Thomas Redecker]
EV[Igo Hatsuyoron]
CP[2007 Thomas Redecker]
RO[Problem 120]
AB[ra][hb][lb][fc][lc][bd][ld][ce][de][fe][le][me][oe][pe][bf]
[mf][of][og][dh][oh][ph][qh][rh][sh][di][mi][ni][oi][pi][aj]
[fj][lj][ak][ek][lk][rk][sk][al][el][il][pl][ql][am][bm][em]
[qm][rm][dn][fn][mn][co][fo][ko][oo][bp][cp][ep][pp][sp][fq]
[pq][qq][sq][cr][nr][pr][bs][ns][os][ps]
AW[qa][ib][jb][mb][rb][hc][qc][cd][jd][nd][od][ke][qe][re][df]
[ff][pf][bg][cg][dg][gg][hg][kg][lg][ng][ah][hi][ki][ri][si]
[bj][cj][jj][nj][oj][pj][qj][dk][jk][ok][dl][jl][rl][sl][hm]
[jm][sm][bn][cn][en][jn][on][rn][sn][qo][ro][so][ap][hp][kp]
[lp][mp][op][qp][eq][rq][ar][ir][mr][or][ms]CA[UTF-8];B[po];W[rr];B[qk];W[ml];B[ll];W[mm];B[lm];W[nn]
;B[no];W[mo];B[ln];W[pn];B[qn];W[rp];B[ol];W[nl];B[nm];W[om]
;B[nk];W[mk];B[mj];W[nk]TR[pk][mk]
;B[rj];W[qi];B[np];W[rs];B[sr];W[oq]
;B[mq];W[lr];B[lq];W[kr];B[kq];W[jp];B[jq];W[jr];B[iq];W[hq]
;B[gr];W[hr];B[ip];W[jo];B[io];W[ho];B[in];W[hn];B[im];W[hl]
;B[ik];W[hk];B[ij];W[hj];B[ii];W[ih];B[ji];W[kj];B[jh];W[kh]
;B[jg];W[jf];B[ig];W[hh];B[if];W[ie];B[hf];W[he]
C[A - my idea
Perhaps played too early ? White would have the move at E15 (= \
W - or perhaps another moves in the top left corner), resulting \
in complicated variations.

B - "standard" Main Path.]
LB[ee:W][rg:A][gf:B]

(;B[gf];W[ge];B[fg];W[ef];B[fh];W[hs];B[ee];W[cm];B[rg]
C[The last moment before Blacks starts with adding stones to the \
Nakade on the left.

A - White captures the Black group on the left.
B - White continues similar to the Main Path (tbd.)]
LB[rf:B][bo:A]

(;W[bo];B[dm]
C[Young-Sun played this move immediatly after White 76 in one of \
her answers, too. So it must be Sente.

A - White connects
Result: Jigo !!!
So Black must not play the second Throw-in at O9 !!!
B - Possible for White (tbd.) ?
C - Tenuki - Can Black be reduced to one eye ? >>> No, Black \
wins the Semeai on the left.]
LB[cm:76][rf:C][bk:B][cl:A]
TR[nk]

(;W[cl]
C[A - Black secures two eyes immediately.
Result: Jigo !!!
B - Better for Black to make this exchange before (tbd.) ? Or \
only a change in the order of moves ?]
LB[pd:B][qf:A]

(;B[qf]
C[A - "Usual" connection, made by Young-Sun now, too.
Result: Jigo !!!
B - Better for White concerning the territory in the top right \
(tbd.) ?]
LB[pd:B][mg:A]

(;W[mg];B[pd];W[pc];B[nb];W[mc];B[ma]
C[A - Necessary for White (tbd.) ?
Result: Jigo !!!
B - Change in the order of moves (tbd.) ?]
LB[fb:B][ob:A]

(;W[ob];B[sf];W[rf];B[pg];W[fb];B[eb];W[gb];B[gc];W[ec]
;B[fa];W[ha];B[dc];W[fr];B[er];W[fs];B[es];W[gs]
C[A - Jigo.
B - Jigo.]
LB[qd:B][rd:A]

(;B[rd];W[qd];B[se];W[rc];B[sd];W[sc];B[sg];W[gq];B[fp]
C[A - Jigo.
B - Jigo.]
LB[fd:B][gd:A]

(;W[gd];B[fd]
C[A - Jigo.
B - Jigo.]
LB[ch:B][dj:A]

(;W[dj];B[ej]
C[A - B +2
B - Jigo]
LB[ch:B][eg:A]

(;W[eg];B[ch]
C[A - B +2
B - B +2]
LB[bh:B][bi:A]

(;W[bi];B[bh];W[eh];B[ei];W[ai];B[af];W[ag];B[bq];W[aq]
;B[na];W[oa];B[la];W[oc];B[kd];W[br];B[ea];W[ga];B[kc];W[kb]
;B[jc];W[ic];B[ka];W[ja];B[gl];W[gk];B[gm];W[fk];B[fl];W[bk]
;B[cs];W[ao]
C[B + 2
=====]
)
(;W[bh];B[ci];W[eh];B[ei];W[bi];B[bq];W[aq]
C[A - B +2
B - B +2]
LB[bk:B][na:A]

(;B[na];W[oa];B[la];W[oc];B[bk];W[kd];B[af];W[an];B[br]
;W[ao];B[kc];W[jc];B[ja];W[gl];B[cf];W[bl];B[as];W[ai];B[ag]
;W[ck]
C[B + 2
=====]
)
(;B[bk];W[oa];B[na];W[nc];B[la];W[kd];B[af];W[an];B[br]
;W[bl];B[as];W[ao];B[cf];W[ai];B[ag];W[ck];B[kc];W[jc];B[ja]
;W[ga];B[ea];W[gl]
C[B + 2
=====]
)))
(;W[ch];B[ci];W[bi];B[af];W[ag];B[eg];W[kd];B[bq];W[aq]
;B[na];W[oa];B[la];W[oc];B[ai];W[bk];B[cf];W[bh];B[kc];W[jc]
;B[ja];W[gj];B[fi];W[br]
C[Jigo.
====]
))
(;W[ch];B[ci];W[bi];B[af];W[ag];B[bq];W[aq];B[dj];W[eg]
;B[eh];W[kd];B[na];W[oa];B[la];W[oc];B[cf];W[ai];B[kc];W[jc]
;B[ja];W[gj];B[fi];W[br];B[fk]
C[Jigo.
====]
))
(;W[fd];B[ed];W[gd];B[bq];W[aq];B[ch];W[bh];B[ci];W[bi]
;B[bk];W[dj];B[ej];W[eh];B[ei];W[eg];B[af];W[an];B[br];W[ao]
;B[cf];W[ai];B[as];W[ck];B[ag];W[bl];B[na];W[oa];B[la];W[oc]
;B[ec];W[kd];B[kc];W[jc];B[ja];W[gl];B[fm]
C[Jigo.
====]
))
(;B[qd]
C[A - Jigo.
B - Jigo.]
LB[gq:B][rd:A]

(;W[rd];B[gq];W[gp];B[fp];W[gd];B[fd];W[ch];B[ci];W[bi]
;B[af];W[ag];B[dj];W[eg];B[eh];W[gj];B[bq];W[aq];B[fi];W[kd]
;B[na];W[oa];B[la];W[oc];B[kc];W[jc];B[ja];W[br];B[cf];W[ai]
;B[fk]
C[Jigo.
====]
)
(;W[gq];B[fp];W[rd];B[ci];W[bi];B[ch];W[bh];B[af];W[dj]
;B[ej];W[bk];B[eg];W[gj];B[na];W[oa];B[la];W[oc];B[fi];W[gd]
;B[fd];W[kd];B[kc];W[jc];B[bq];W[aq];B[ja];W[gl];B[br]
C[Jigo.
====]
)))
(;W[fb];B[eb];W[gb];B[gc];W[ec];B[fa];W[ha];B[dc];W[ob]
C[???]
))
(;W[pd]
C[A - "Usual" forcing move.
B - Is the Hasami-Tsuke possible (tbd.) ?
C - Must Black play this Sente move now (tbd.) ? Is this move \
really Sente ?]
LB[gb:C][nb:B][mc:A]

(;B[mc]
C[A - "Usual" answer (tbd.).
B - Better for White (tbd.) ?]
LB[gb:B][nb:A]

(;W[nb];B[nc];W[oc];B[ma]
C[A - Saves only two stones (tbd).
B - Better for White now (tbd.) ?]
LB[gb:B][oa:A]

(;W[oa];B[gb];W[kd];B[gs];W[gq];B[fr];W[mg];B[pg]
C[???]
)
(;W[gb];B[fb];W[fa];B[ea];W[ga];B[gc];W[ha];B[eb];W[oa]
;B[ci];W[bi];B[ch];W[bh];B[gs];W[gq];B[fr]
C[???]
))
(;W[gb]))
(;B[gb]
C[A - Must White make two eyes ?
X - Tenuki - Can White live with a threat of connecting along \
the top (tbd.) ?]
LB[kd:A]
;W[kd])
(;B[nb];W[mc];B[ma]
C[A - Necessary for White (tbd.) ?
B - Better for White (tbd.) ?]
LB[gb:B][ob:A]

(;W[ob];B[gb];W[kd]
C[???]
)
(;W[gb];B[fb];W[fa];B[ea];W[ga];B[gc];W[ha];B[eb];W[ob]
C[???]
))))
(;B[pd]
C[Threatens Q18 for a greater life.]
TR[ob]
;W[rf];B[ob]
C[A - Hane (tbd.). May be that Black lives.
Young-Sun said that 79 is greater than 8 points if unanswered \
by White (during the Endgame-discussion concerning the top left \
center).
X - another move for White (tbd.) ?]
LB[pd:79][la:A]
;W[la];B[ka];W[ma];B[kb]
C[A - Watari.
X - another move for White (tbd.) ?]
LB[oa:A]
;W[oa];B[nb]LB[mc:B][na:A]

(;W[na];B[mc];W[pa];B[pc]
C[A - Black lives.
B - White dies in the corner.]
LB[mg:B][sa:A]

(;W[sa];B[mg]
C[Black lives.]
)
(;W[mg];B[qb];W[sa];B[pb];W[rd];B[sc]
C[White dies in the corner.]
))
(;W[mc];B[pc];W[pb];B[oc];W[na];B[md];W[pa];B[nc];W[sa]
;B[qd];W[rd];B[mg]
C[Black lives.]
)
(;W[pc];B[mc];W[oc];B[mg]
C[Black lives.]
)))
(;W[rf];B[cl]
C[A - Black wins.
B - Black wins.
C - Black wins.]
LB[ao:C][bl:B][ck:A]

(;W[ck];B[bl];W[ao];B[bi];W[ci];B[ch];W[bh];B[ai]
C[Black wins.]
)
(;W[bl];B[an];W[ck];B[ao];W[cl];B[aq]
C[Black wins.]
)
(;W[ao];B[dj];W[ck];B[bi]
C[A - Black wins.
B - Black wins.
C - Black wins.]

(;W[ci];B[ch];W[bl];B[bh]
C[Black wins.]
)
(;W[bl];B[bh]
C[Black wins.]
)
(;W[ai];B[bh];W[ag];B[bl]
C[Black wins.]
)))
(;W[bk]))
(;W[rf]))
(;B[rg]
C[B 67 is my idea. Takes 3 points of White territory here. But \
is Gote.

Young-Sun thinks that F is indeed the strongest response in the \
top left corner.

67 could probably played some moves earlier. Every "running"-move \
of the marked chain in the center would provide a Ko-threat. \
Might be necessary, because Young-Sun had developed some variations \
with a Ko in the top left corner (not included in this SGF) won \
by White.]
LB[gf:G][ge:H][ee:F][gd:I][fd:E][ed:D][gb:A][fb:B][eb:C]
TR[ji][jh][jg][ig][if][hf]

(;W[ee];B[qf];W[ed];B[dc];W[ec]
C[Strongest move for White, Young-Sun said.]
;B[eb]
C[To cut immediately with A is better than connection before at \
B, Young-Sun said.]
LB[dd:B][db:A]
;W[db]
C[To cut here has a value in itself, Young-Sun said.

Playing first at B is not so good.

Young-Sun's first idea for Black now had been to connect at C, \
but this leads to the Ko mentioned before.

To take the cutting stone with A is better for Black ! He will \
win by 4 points !]
LB[fb:C][dd:B][cb:A]
;B[cb]
C[Should White connect at A, Black B would take White's group a \
liberty.

Perhaps it might even possible for Black to answer with C.]
LB[da:C][cc:B][dd:A]
;W[cm]
C[Playing here is bigger than continuing at the top.

Should Black answer at B (not included here), there would be \
a Jigo in the end.

Black A is best for Black.]
LB[an:A][gb:B]

;B[an];W[bo];B[ao];W[aq]
C[A - played by Young-Sun
B - better for Black in my opinion, this move is Sente now.]
LB[br:A][dm:B]

(;B[br];W[ai];B[bq]LB[dd:B][fb:A]

(;W[fb];B[da];W[mg];B[pd];W[pc];B[nb];W[mc];B[ma];W[ob]
;B[sf];W[rf];B[pg];W[gb];B[dd];W[dm];B[eo];W[bk];B[as];W[bl]
;B[ap];W[fh];B[dj];W[hs];B[gs];W[gq];B[fr];W[se];B[gf];W[ge]
;B[eh];W[eg];B[fi];W[oa];B[na];W[fa];B[ea];W[ch];B[ci];W[bi]
;B[af];W[gi];B[kd];W[kb];B[kc];W[jc];B[ka];W[ja];B[la];W[oc]
;B[qd];W[rd];B[sg]
C[B + 2
=======]
TB[fs][es][ds][cs][er][dr][ar][eq][dq][cq][aq][dp][do][en][ej][ei][qg][pf][be][ae][cd][ad][cc][bc][ac][db][bb][ab][ca][ba][aa]
TW[ls][ks][js][is][cl][ck][gh][bh][fg][ef][je][fe][sd][id][hd][gd][fd][sc][rc][ic][gc][fc][sb][qb][pb][hb][sa][ra][pa][ia][ha][ga]
)
(;W[dd]
C[Open question: Might this move be better for White ?

A - peaceful answer
B - better in Joachims opinion. Might be the reason why Young-Sun \
didn't play 84 here.]
LB[da:B][cc:A]

(;B[cc];W[fb];B[da];W[gb];B[gf];W[ge];B[fg];W[ef];B[fh]
;W[hs]
C[White has won 3 points in the top left, but will not get the \
3 points of territory in the center.

So even the peaceful answer might be possible for Black, in my \
opinion.]
)
(;B[da]
C[Black resists.]
;W[gb]
(;B[fb]
(;W[bc];B[cc];W[ad];B[be];W[af];B[bb];W[ab];B[ac]
C[Ko
Es geht nur um die C15-Gruppe; D17 lebt schon.]
;W[bk]
;B[as];W[bc];B[pm];W[nm];B[ac];W[ap];B[aq];W[bc];B[ef];W[eg]
;B[ac];W[bl];B[ap];W[bc];B[fd];W[ef];B[ac]
(;W[pg];B[mg];W[bc];B[ge];W[gf];B[ac];W[mh];B[nh];W[bc]
;B[gc];W[ha];B[ac];W[ne];B[nf];W[bc];B[pd];W[pc];B[ac];W[ei]
;B[ae]
C[S gewinnt]
;W[dm];B[eo];W[mc];B[ma];W[na];B[la];W[nb];B[ej];W[dj]
;B[fi];W[eh];B[hs];W[is];B[gs];W[gq];B[fr];W[kd];B[kc];W[jc]
;B[fa];W[ga];B[ja];W[hd];B[ka];W[ia];B[qd];W[rd];B[lh];W[li]
;B[rf];W[sf];B[gl];W[gk];B[gm];W[fk];B[fl];W[fh];B[gi];W[ag]
;B[md];W[oc];B[sg];W[se];B[mh]
C[S + 5
=====]
)
(;W[mg];B[pg];W[bc];B[ge];W[gf];B[ac];W[ei]
(;B[ae]
C[Difficult to estimate the final score.]
)
(;B[pd]
C[besser?]
;W[pc];B[ae];W[dm];B[eo];W[hs];B[qd];W[rd];B[nb]
;W[mc];B[ma];W[ob];B[gs];W[gq];B[fr];W[fi];B[ej];W[dj];B[na]
;W[oa];B[la];W[oc];B[gc];W[ha];B[kd];W[gj];B[jc];W[ic];B[kc]
;W[fa];B[ea];W[ga];B[ja];W[ia];B[ka];W[rf];B[sf];W[hd];B[se]
;W[sd];B[sg];W[ag]
C[W + 2
======]
)))
(;W[cc];B[bc];W[fd];B[gc];W[ha];B[gd];W[ge];B[db];W[dm]
;B[eo];W[pd];B[nb];W[mc];B[ma];W[ob];B[hd];W[id];B[hs];W[is]
;B[gs];W[gq];B[fr];W[fh];B[dj];W[bk];B[as];W[bl];B[ap];W[af]
;B[ae];W[cf];B[be];W[nc];B[na];W[oa];B[la];W[mg];B[sf];W[rf]
;B[pg];W[se];B[eh];W[eg];B[fi];W[gi];B[kd];W[kb];B[kc];W[jc]
;B[ka];W[ja];B[fa];W[ga];B[ch];W[bi]
C[B + 3
=====]
))
(;B[cc];W[fb]
C[Same position as before.]
;B[gf];W[ge];B[fg];W[ef];B[fh];W[hs];B[pd]
;W[pc];B[qd];W[rd];B[nb];W[mc];B[ma];W[ob];B[dm];W[cl];B[gs]
;W[gq];B[fr];W[mg];B[sf];W[rf];B[pg];W[af];B[be];W[bk];B[as]
;W[bl];B[ap];W[dj];B[ej];W[ch];B[ci];W[bi];B[eg];W[gj];B[fi]
;W[nc];B[na];W[oa];B[la];W[kd];B[kc];W[jc];B[fa];W[ga];B[ea]
;W[se];B[ja];W[ia];B[ka];W[ae];B[ad];W[ag];B[sg];W[kf];B[ab]
C[B + 1
=====]
))))
(;B[dm];W[cl]
C[Black has won two points here.

He needs not play at the marked point and White 82 is no point \
of territory for White any more.]
TR[eo]
;B[br]
C[The rest of the game follows Young-Sun's suggestion.]
;W[ai];B[bq];W[bk];B[as];W[fb];B[da]
;W[mg];B[pd];W[pc];B[nb];W[mc];B[ma];W[ob];B[sf];W[rf];B[pg]
C[A - Young-Sun
B - vorher den Stein anbinden (mit einfacher Antwort von mir)]
LB[dd:B][gb:A]

(;W[gb];B[dd];W[bl]
C[A - Young-Sun
B - Jederzeit möglich]
LB[ap:A][gf:B]

(;B[ap];W[fh];B[dj];W[hs];B[gs];W[gq];B[fr];W[se];B[gf]
;W[ge];B[eh];W[eg];B[fi];W[oa];B[na];W[fa];B[ea];W[ch];B[ci]
;W[bi];B[af];W[gi];B[kd];W[kb];B[kc];W[jc];B[ka];W[ja];B[la]
;W[oc];B[qd];W[rd];B[sg]
C[B + 4
=====]
)
(;B[gf];W[ge];B[fg];W[ef];B[fh];W[hs];B[ap];W[fr];B[er]
;W[fs];B[es];W[gs];B[gq];W[gp];B[fp];W[se];B[ch];W[bi];B[qd]
;W[rd];B[af];W[dj];B[ej];W[eg];B[eh];W[gj];B[fi];W[fa];B[ea]
;W[oa];B[na];W[kd];B[kc];W[jc];B[la];W[oc];B[ja];W[ia];B[ka]
;W[sg];B[ag];W[bh];B[sf];W[dr];B[dq];W[sg];B[gc];W[ha];B[sf]
;W[ds];B[cs];W[sg];B[md];W[nc];B[sf];W[ne];B[nf];W[sg];B[pm]
;W[nm];B[sf];W[kn];B[lo];W[sg];B[lf];W[kf];B[sf];W[li];B[mh]
;W[sg];B[rc];W[sc];B[sf];W[ca];B[ba];W[sg];B[cf];W[sf]
C[S + 3
=====

Also doch nicht so gut.]
))
(;W[dd];B[cc];W[gb];B[gf];W[ge];B[fg];W[ef];B[fh];W[hs]
;B[gs];W[gq];B[fr];W[se];B[dj];W[oa];B[na];W[kd];B[kc];W[jc]
;B[qd];W[rd];B[ch];W[bi];B[af];W[cf];B[be];W[fa];B[ea];W[eg]
;B[eh];W[gj];B[fi];W[ja];B[sg];W[bl];B[ap];W[fk];B[fl];W[gk]
;B[gm];W[gn];B[gl];W[kf];B[ej]
C[S + 3
=====]
)))
(;W[rf];B[gf];W[ge];B[fg];W[ef];B[fh];W[hs];B[ee];W[cm]
;B[pd];W[pc];B[nb];W[mc];B[ma];W[ob];B[an];W[bo];B[ao];W[aq]
;B[bi];W[ai];B[bh];W[ag];B[bk];W[ck];B[bl];W[cl];B[ak];W[aj]
;B[bl];W[ao];B[am];W[bk];B[al];W[mg];B[dj];W[ka];B[la];W[kb]
;B[eg];W[kc];B[af];W[lf];B[cf];W[kn];B[br];W[lo];B[bq];W[li]
;B[as];W[mh];B[dm];W[nh];B[ch];W[kk];B[ci];W[kl];B[bm];W[an]
;B[al];W[km];B[ak];W[nc];B[na];W[oa];B[bl];W[ne];B[nf];W[kd]
;B[am];W[bm];B[al];W[qf];B[ak];W[qd];B[nq];W[oq];B[qr];W[sf]
;B[bl];W[am];B[al];W[sg];B[qs];W[ss];B[sq];W[pg];B[pm];W[nm]
;B[sp];W[qg];B[sr];W[gb];B[fb];W[fa];B[ea];W[ga];B[gc];W[ha]
;B[eb];W[fr];B[er];W[fs];B[es];W[gs];B[gq];W[gp];B[fp];W[gj]
;B[fi];W[gd];B[fd];W[md]
C[B + 6
======]
)))
