(;
AB[om][pm][qm][nn][pn][no][oo][po][op][oq][or][pr]
AW[qk][nl][ol][ql][nm][rm][mn][qn][mo][qo][pp][mq][pq][mr][qr]
C[Black plays.

Source:
    From a Korean life and death pamphlet.]
(;
B[qq]
C[Cutting at White's weak point is the right idea, but bad timing.];
W[qp]
C[If necessary, White's corner group can now capture the Black stone for a 2nd eye.];
B[rq];W[rr];B[rn]
C[Another good move, but too late.];
W[rp]
C[White can dodge to here to make life in the corner.];
B[rl]
C[Black seems to make life by capturing a stone of his own, but ...];
W[rk];B[sm];W[so]
LB[rm:A]
C[... with a false eye at A, Black's entire group dies!]
)
    (;
    B[rn]
    C[Amazingly, the only move that saves Black.]
    (;
    W[ro];B[qq];W[qp];B[rq];W[rr]
    C[White still looks safe, but ...];
    B[sr];W[rp];B[sq]
    C[... with a liberty shortage, White cannot give atari.  Black captures the 2 stones to live!]
    )
        (;
        W[qp]
        C[White can protect the cutting point weakness from the previous variation, but now Black has another resource.];
        B[ro]
        C[The key sente move that saves the Black group.];
        W[rp]
        C[White cannot let Black give atari on this point.];
        B[rl];W[so];B[sm];W[rk]
        LB[rm:A]
        C[Black still has a false eye at A, but ...];
        B[rs]
        C[... Black has this eye-stealing tesuji.  White's corner lacks eyespace, and Black wins the semeai.];
        W[qs]
        C[For example ...];
        B[rr];W[rq];B[ps]
        )
    )
)

