(;
GM[1]FF[4]VW[]AP[Many Faces of Go:10.0]
SZ[19]
HA[0]
ST[0]
PB[Yilun Yang]
PW[Yigang Hua]
DT[2002-04-28]
KM[5.5]
RE[Black won by 7.5]
AN[Commentary by Yilun Yang]
US[Edited by Chris Garlock and William Cobb]
EV[Costen Open Tournament]
GN[2002 Cotsen Open Demo Game]
CP[American Go Association]
BR[7P]
WR[8P]
RO[Pro Demonstration Game]

C[Cotsen Open Tournament
Pro Demonstration Game
April 28, 2002
W: Yigang Hua, 8P
B: Yilun Yang, 7P
Commentary by Yilun Yang
Edited by William Cobb and Chris Garlock in Many Faces of Go
11
An original commentary published in the 11/11/02 American Go
E-Journal.
]goWriteVersion[1.4p,Unregistered version]KI[11];B[pd];W[dp];B[pq];W[cd];B[ec];W[id]
C[White 6 is a resonable pincer since White has to be defensive
on the top side.
];B[ef];W[cg]
;B[mc]
C[Black 9 is a proper move because it isn't easy for Black to attack
White's single stone.
];;W[qk]
C[W10 should be at R5.
];B[qo];W[qh];B[jq];
(;W[rd]
C[W14: See variations for a better move.
];B[qc]
C[B15: Now White's shape is thin.
];W[fq];B[qg]
C[B17 is a good forcing move; it attaches to a strong stone.
];W[rg];B[rf]
C[B19 is a strong move.
];W[qf];B[pg];
(;W[rh]
C[W22: See variation for White S15.
];B[qe];W[ph];B[pf]
C[B25: Black gets a benefit.
];W[gc];B[dd]
C[B27 is necesssary for connection.
];W[cc];B[ce];W[be]
;B[bf]
C[B31 is a common tesuji.
];W[cf];B[de]
C[Black 33 makes a solid shape outside.
];W[bd];B[eh];W[di];B[ib]
C[B37 is the correct direction of attack in this situation.
];W[ic]
C[W38 is the best defense.
];B[hb]
C[B39 is an important point.
];W[gb]
;
(;B[hc]
C[B41: See variation for a black extension at K18.
];W[hd]
C[W42: This exchange creates an exact cutting point in White's
shape.
];B[jb];
(;W[eb]
C[W44: See variation for a better move.
];B[gd]
C[B45 is a severe cut.
];W[fc];B[fd]
C[B47: Now White has a floating weak group.
];W[ig];B[ga];W[fb];B[ii]
C[B51 is an important point. Black controls this game.
];
C[W52 should be at L12.
]
;W[ei];B[gh];;W[ji]
C[W54 should be at L12.
];B[ih];W[kc];
(;B[kb]
C[B57: See variation for why 57 is not at K17.
];W[jh];B[jg]
C[B59 is a severe cut.
];W[kg];B[jf];W[kf];B[if]
C[B63: Now Black is comfortable: his center group is strong, and
this leaves a weakness in White shape.
];W[lc];B[lb]
;W[md];B[nd];W[le];B[jj]
C[B69 is an important point.
];W[ne];B[od];W[li];B[lj]
C[B73 is a useful forcing move.
];W[mj];B[lk]
C[B75: Black gets thickness in the center, which helps the bottom
area.
]
;W[mi];B[bo]
C[B77 is a common reduction.
];W[bp]
C[W78 is the correct response since White needs more territory.
];B[cp];W[co];B[cq];W[bq];B[do];W[cn];B[dq]
;W[ep];B[bn];W[br];B[cm];W[dn];B[em]
C[B91 is a fast move, it is good for developing the center.
];W[en];B[fn];W[dm];B[dl]
;W[eo];B[cl]
C[B97 is good enough for Black, reducing the left side.
];W[cj];B[fm];
(;W[nn]
C[W100: See variation.
];
(;B[mp]
C[B101: See variation for an alternative.
];W[ir]
C[W102 is good timing.
];B[jr];W[iq];B[ip];W[hp];B[ho];W[js]
C[W108 is a clever move.
];B[jp]
;W[qn]
C[W110 is a good forcing move.
];B[rn];W[ro]
C[W112 is a nice tesuji.
];B[rp];W[po];B[qp];W[rm];B[so];W[qm];B[hq]
;W[hr];B[gp];W[gr];;B[fj]
C[B123 should be at L1.
];W[ek];B[el];W[fk];B[gk];W[kr]
;B[dh];W[ch];B[fi]
C[B131 is a thick move, fixing bad aji in Black's shape.
];W[mr];B[or];
(;W[lm]
C[W134: See variation for a better alternative.
];B[mk];W[nk];B[mm];W[mn];B[nl];W[lo];B[kn];W[ln]
;B[ok];W[nj];B[om];W[jl]
C[W146: Black gains a little bit with this exchange.
];B[pn];W[ll];B[ml];W[pl];B[ol];W[lp]
;B[ej]
C[B153 is a thick move.
];;W[ik]
C[W154 should be at P13.
];B[ng]
C[B155: Now Black is winning.
];W[ij];B[oo];W[np];B[mf];W[me];B[je]
;W[ke];B[ki];W[kh];B[kj];W[oj];B[pk];W[pj];B[dc];W[db];B[he]
C[B171 is a thick move.
]
;W[sf];B[se];W[sg];B[re];W[bk];B[bl];W[sm];B[pm];W[ql];B[ck]
;W[bj];
(;B[dj]
C[B183: See variation for an alternative.
];W[op]
C[W184 is too soon.
];B[pp]
C[B185: White loses an important liberty.
];W[gl]
C[W186 is a good move.
];B[ci];W[bi];B[fl];W[gj];B[dk]
;W[hk];B[nr]
C[B193 is the biggest move.
];W[nq];B[ms]
C[B195: This is painful for White.
];W[lr];B[no];W[mo];B[ap];W[ao];B[an]
;W[cr];B[ak];W[fa];B[di];W[ha];B[aj];W[bh];B[fk];W[hi];B[hh]
;W[hm];B[ia];W[oe];B[pe];W[ai];B[al];W[in];B[jn];W[hn];B[fo]
;W[gq];B[fp];W[eq];B[hp];W[oh];B[nf];W[nh];B[jm];
(;W[im]
C[W230: See variation for an alternative.
];B[kl];W[km];B[jk];W[kk];B[cb];W[bb];B[kl];W[mb]
;B[nc];W[kk];B[mg];W[lh];B[kl];W[nb];B[il];W[ob];B[pb];W[la]
;
(;B[oa]
C[B249: See variation for a better alternative.
];W[jc];B[oc];W[ka];B[ga]
C[Now White has two ko-threats locally.
];W[pa];B[qa];W[ha];
(;B[ks]
C[B257: See variation for an alternative.
];W[ls];B[ga];W[ma];B[pa];W[ha];
(;B[is]
C[B263: See variation for an alternative.
];W[ja];B[ks];W[mq];B[js]
C[B267: Black got very little profit on the bottom.
];W[kq];B[ns];W[sn];B[ro]
;W[oq];B[pr];W[ie];B[hf];W[ko];B[jo];W[on];B[po];W[dg];B[eg]
;W[aq];B[hs];W[gs];B[jd];W[kd];B[ao];W[af];B[df];W[og];B[of]
;W[mh];B[lf];W[na];B[nm];W[kp];B[lg];W[tt];B[tt]
C[Black won by 7.5 points.
];W[tt]TC[15])
(;B[oq];W[ja];B[mq]
C[Black is way ahead.
]))
(;B[is];W[ks];B[ga];W[ma];B[pa];W[ha];B[oq];W[mq];B[ga]))
(;B[ka];W[ma];B[oa];W[jc];B[ga]
C[Now Black will win this ko, since White doesn't have a local
ko-threat.
]))
(;W[kl];B[jc];W[jd];B[kd];W[ld];B[ie];W[kd];B[df];W[ls]
;B[dg];W[af];B[ns];W[kq];B[oq];W[mq];B[sn];W[aq];B[gn];W[ga]
;B[ao]TC[13]))
(;B[hl];W[dj];B[il];W[jk];B[jm];W[km];B[dk]
C[Black is way ahead.
]))
(;W[ml];B[ll];W[mm];B[ng];W[oh];B[mf];W[me];B[nf];W[kn]
;B[nh];W[ni];B[ki];W[kh];B[kj];W[lh];B[jm]
C[But White is still behind.
]))
(;B[gr];W[fr];B[mp]
C[Black is ahead.
]))
(;W[pr];B[oq];W[or];B[qr];W[nq]))
(;B[jc];W[jd];B[kd];W[ke];B[ld];W[jh]
C[Now Black can't cut at K13.
]))
(;W[fe];B[fb];W[hg]
C[This is better for White than game's situation.
]))
(;B[jb];W[eb];B[hc];W[gd];B[hd];W[ge];B[he];W[fg]
C[This isn't good for Black.
]))
(;W[re];B[rh];W[sf];B[qi]
C[The ladder works for Black. This is a bad result for White.
]))
(;W[qc];
(;B[pc];W[qd];B[qe];W[re];B[rf];W[qf];B[pe];W[rg];B[rd]
;W[sf]
C[White makes a solid position on the right side.
];B[rc];W[fq])
(;B[qd];W[pc];B[oc];W[ob];B[nb];W[od];B[nc];W[rd];B[re]
;W[rc];B[qf];W[pb];B[oe]
C[White gets the corner with sente. This result isn't good for
Black.
];W[gc])))
