(;
AB[nc][qd][cf][ef][fg][fh][eh][di][dj][dk][qn][cq][dq][jq][pq][er][fr]
AW[dd][fd][df][dg][dh][eg][ch][ci][cj][qh][qk][cl][cp][dp][ep][fq][gq]
C[Black's response to the marked play?

Source:
    American Go Yearbook 2003, p. 72
    "Top Amateur Game"
    Black:  Mero Csaba 5d
    White:  KGS player
    Commentary:  Guo Juan 5P]
TR[df]
(;
B[cc]
C[White's top left corner looks very big, so Black must be aware of what is possible here.]
(;
W[cd]
C[One of a couple of options for White.];
B[db]
C[This kosumi is a nice move to remember.];
W[fb];B[bd];W[be];B[bb];W[ad];B[bc];W[ca]
C[The only move, if White wants to kill.];
B[ba]
C[Black makes an eye in the corner.];
W[da];B[eb];W[ea];B[fc];W[gc];B[ec];W[hb];B[ed]
C[White is too thin on the outside - Black escapes.  The follow-up moves are left as an exercise for the reader.]
)
    (;
    W[dc]
    C[The other option.];
    B[bb]
    C[Another nice kosumi to remember.];
    W[db];B[cd];W[be];B[ce];W[bf];B[bd]
    C[Forcing.];
    W[bg];B[ac]
    C[Black lives.]
    )
)
    (;
    B[dl]
    C[In the game, Black pushed here.];
    W[cm]
    C[White has to respond.];
    B[hc]
    C[In the game, Black then played from the outside here.  But Black has to be very careful not to ruin the aji of the corner invasion.

In fact, later in the game, Black does lose the chance to invade the top left, but still was fortunate enough to win the game.]
    )
)

