(;
AB[pd][qf][nc][jc][jd][je]
AW[ke][kd][kf][lc][qh]
C[White plays against the upper right corner.]
(;
W[qc]
C[In the game, after White invaded at the 3-3 point here, the resulting complications were such that both these strong players made mistakes.];
B[pc];W[qd];B[qe];W[pb];B[ob];W[rb];B[rh];W[ri];B[pa];W[qa];B[qb]
C[White won the ko and the game, but not without help from Black.]
)
    (;
    W[rd]
    C[This invasion may not have been the best for the given game, but the technique is simpler and effective.]
    (;
    B[re]
    C[Black can block immediately here, but ...];
    W[qd]
    C[... White now has a sequence of straightforward forcing moves.];
    B[qe];W[pc];B[oc];W[qb];B[pb];W[qc];B[ob];W[se];B[sf];W[sd];B[oe]
    C[White can live in the corner.]
    )
        (;
        B[qd];W[re]
        (;
        B[rf]
        C[Black can prevent the outside connection, but ...];
        W[qb]
        C[... White lives.]
        )
            (;
            B[rc]
            C[Black can also try to protect the corner, but ...];
            W[rb];B[qc];W[rf]
            C[... White reduces the corner and keeps a follow up for later.]
            )
        )
    )
)

