(;
AB[qr][rr][pq][oq][nq][qp][qo][qn]
AW[qq][rq][rp][ro][pr][or]
C[White plays.

Source
    Tesuji, Ch. 5, pp. 81-82
    James Davies, Ishi Press]
(;
W[ps]
C[Making an ugly empty triangle
is the only move that works!];
B[sr];
W[qs];
B[rn];
W[rs]
)
    (;
    W[sr]
    C[White 1 is an innocent
looking mistake.]
    (;
    B[sq]
    C[Black has this nasty
surprise for White.];
    W[sp];
    B[rs];
    W[qs]
    C[And White has to fight an
unfavorable ko.]
    )
        (;
        B[rs]
        C[Perhaps White was hoping
for this bad Black move?];
        W[sq]
        C[Thanks to Black's mistake,
White can take the corner.]
        )
    )
)

