(;
AB[db][ec][fc][hd][ic][ib][qd][oc][dg][nc][pd][qg][mg][lg][kg]
AW[cb][cc][dd][cf][cg][fe][gf][if][je][jc][jb][le][nd][qe][og]
C[Should White play against the upper
left Black group or play elsewhere?

Source:
    Go World #34, Winter 1983-84, pp. 42-43
    Otake Hideo  vs.  Cho Chikun
    Hane Yasumasa commentary.]
(;
W[ga]
C[Correct.

White won't kill Black, but no matter how
Black responds, White can help his position
at the top or hurt Black's upper right.]
(;
B[ia]
C[If Black descends here...];
W[da]
C[White reduces Black to one eye in the
following sequences.];
B[ea];
W[gc]
(;
B[gd];
W[fb]
C[And Black dies.]
)
    (;
    B[gb];
    W[fb];
    B[hb];
    W[gd]
    C[And again Black dies.]
    )
)
    (;
    B[ja]
    C[If instead, Black hanes here...];
    W[lb]
    C[White can play here in sente to affect
Black's upper right corner.]
    )
    (;
    B[gb]
    C[And if Black makes life here...];
    W[fa];
    B[ea];
    W[ia];
    B[fb];
    W[ha];
    B[hb];
    W[ja];
    B[dc];
    W[gd];
    B[jd];
    W[kd];
    B[id];
    W[lc]
    C[Again White can make a move around here
in sente to affect the upper right corner.]
    )
)
    (;
    W[]
    C[In the game, White played elsewhere and
lost the opportunity to gain on the outside
by attacking the Black upper left group.

White may have lost the game as a result.]
    )
)
