(;
AB[bb][cb][cc][dd][ed][ee][fd][ec][eb][cf][ci][dl][cn][fp][pd][pp]
AW[bc][cd][ce][de][dc][ef][ff][fe][gd][fc][ch][ck][cl][dp][bh]
TR[fp]
PL[W]
C[White's response to the marked approach?

Source:
     American Go Journal, Vol. 34, No. 1, p. 14
    1999 World Amateur Championship
    Yi Guo Sun (China) vs. Ted Ning (USA) (White)
    Commentary:  Jie Li]
(;
W[eo]
C[In the game, Ning incorrectly responded here.  Now Black's position is too flexible.

See the variation.];
B[cq]
C[The game continued with the 3-3 invasion.];
W[cp];B[dq]
C[What should White do now?]
(;
W[dm]
C[In the game, Ning incorrectly attached here.

See the variation.];
B[bp];W[bo];B[bq]
C[White is over-concentrated.

Black goes on to win the game.]
)
    (;
    W[bq]
    C[White should hane here.];
    B[br];W[bp];B[ep];W[dn];B[jq]
    C[A normal result for both sides.]
    )
)
    (;
    W[fo]
    C[White must attach here.  A possible sequence follows.];
    B[go];W[eo];B[cq];W[gp]
    C[Now White can transfer his thickness to the lower side.];
    B[cp];W[hp]
    C[The game will become a long race.]
    )
)

