(;
AB[db][gb][fc][hc][ic][jc][qc][qd][gd][id][kd][ld][md][pd][je][ke][ne][oe][re][rf][qf][lg][lh][li][hh][jh][ji][qh][qi][qj][qk][ql][qm][rh][ci][si][nj][nk][rj][kk][kl][ml][mm][ol][pl][fn][gn][on][ho][bp][bq][br][gp][ip][iq][cq][kq][lq][mq][oq][pq][dr][cs]
AW[eb][ec][fb][cc][kc][lc][mc][oc][pc][dd][nd][ie][if][ig][me][mf][mg][qe][cf][kf][kg][lf][pf][qg][rg][sg][nh][ni][ph][pi][pj][pk][sh][jj][jk][ck][dk][ok][nl][nm][gm][om][pm][dn][hn][in][kn][bo][io][no][qo][cp][dp][jp][kp][lp][op][pp][dq][er]
C[Black plays.
Commentary:  Yilun Yang 9P

Source:
    American Go Yearbook 2003, p. 49
    Yilun Yang 7P (Black) vs. Chen Zude 9P
    2003 Cotsen Open]
(;
B[gf]
C[The game move, but too hurried.

This move looks nice, but Black cannot really kill White's center group.]
(;
W[gg]
C[The correct way to split Black.]
(;
B[hg]
C[The game move, but too tight.  Black cannot kill White's group.];
W[hf];B[gh];W[ge];B[fg]
C[Black takes outside profit, but ...];
W[fe]
C[... when White runs out here, Black's group above is hurt.

Black still has a playable game, but Black has missed the earlier chances.

For reference, the remainder of the game appears below without comment.];
B[nb];W[nc];B[pb];W[ob];B[qb];W[jb];B[ib];W[kb];B[oa];W[na];B[ma];W[la];B[mb];W[lb];B[ja];W[na];B[mb];W[ha];B[ia];W[pa];B[fd];W[he];B[fa];W[hd]
C[Black resigns.]
)
    (;
    B[gi]
    C[Instead, Black should defend here.];
    W[hg];B[ei]
    C[Black's group is fine.]
    )
)
    (;
    W[ih]
    C[Pushing here doesn't work.];
    B[ii];W[hi];B[hj];W[gi];B[gj];W[fi];B[hg];W[kj];B[lj];W[ij];B[il];W[hk];B[ik];W[gk];B[jl];W[fj];B[og]
    C[Black will win the semeai.]
    )
)
    (;
    B[gg]
    C[This diagonal move doesn't work either.];
    W[gf];B[ff];W[fe];B[ge];W[hf];B[fg];W[fd]
    C[Clearly bad for Black.]
    )
    (;
    B[gj]
    C[Instead, Black should just defend here.];
    W[gf]
    C[After White runs out, ...];
    B[nb]
    C[... one possible straightforward sequence follows.];
    W[nc];B[pb];W[ob];B[qb];W[jb];B[oa];W[mb];B[na];W[pa];B[qa];W[ma];B[pa];W[ia];B[ha];W[ka];B[ib];W[lb]
    C[This ko is good enough for Black to win the game.]
    )
)

