(;
AB[rq][pq][pr][oq][nr][mr]
AW[or][os][ps][nq][mq][lq][jq]
C[White plays.

Source:
    Korean problem set pamphlet.]
(;
W[qs]
C[Crawling is too slow to save the 3 White stones!];
B[rs]
C[Black can keep White's group down to 2 liberties.];
W[rr];B[qr];W[ss];B[ns]
C[White loses the semeai.]
)
    (;
    W[qr]
    C[White's hane looks more promising, but ...];
    B[rs]
    C[... Black has this edge tesuji.];
    W[rr];B[ns];W[qs];B[sr]
    C[White only has a ko.]
    )
    (;
    W[rs]
    C[The only move!];
    B[qr]
    C[Black's only hope to win the semeai.];
    W[qs];B[rr];W[lr]
    C[White's stones live.  Even though Black's group has the same number of liberties as White's, Black has to waste a move to put the White group into atari.]
    )
)

