(;
AB[rs][qr][pr][oq][po][oo][qm][om][ol][ok][pj]
AW[rr][qq][qp][qo][pl][pk][qj][qi][qh]
C[White plays

Source:
    Qi Jing Zhong Miao #466, an ancient collection of mostly kyu level life and death problems.

Side variation analysis:
    Myron Souris]
(;
W[rl]
C[A standard tesuji, but how can White connect?!]
(;
B[rm]
C[Black seems to be able to easily block White from connecting.];
W[sm]
C[But White has another not so common tesuji!]
(;
B[ql];W[pm]
(;
B[rk];W[qk];B[qn];W[sl]
(;
B[pn];W[so]
C[A nice tesuji that keeps White connected.]
)
    (;
    B[sn]
    C[Black does not have time to block here.];
    W[pn]
    C[Now Black is the one cut off.
One possible sequence follows.];
    B[sk];W[ro]
    (;
    B[rn];W[sl];B[so];W[sp];B[sq];W[sr];B[rp];W[rq];B[sp];W[rl];B[sm];W[rl];B[sl];W[rj]
    C[White wins the semeai by 1 move.]
    )
        (;
        B[sl];W[rn];B[rq];W[so];B[pq]
        C[White has an advantageous 2-step ko.  And White takes 1st.]
        )
    )
)
    (;
    B[qk];W[rk];B[sn]
    C[Capturing the 3 White stones to the left lets White connect.
So if Black tries to keep White separated here, ...];
    W[pn]
    C[And Black's right edge group can capture 3 stones, but cannot make 2 eyes.  Black takes a big loss.]
    )
)
    (;
    B[rn];W[ro];B[sn];W[pm];B[ql];W[qk];B[rk];W[sl];B[sk];W[sl]
    )
)
    (;
    B[qn]
    C[Another Black try that seems to easily keep White from connecting.];
    W[rn];B[rm];W[sm];B[rk];W[ql];B[ro];W[sn];B[sk];W[sl]
    C[And White stays connected by the skin of his teeth!]
    )
)
    (;
    W[pm]
    C[Fails];
    B[pn]
    C[White's 3 stones lose a valuable freedom over the correct line.]
    (;
    W[rl]
    C[Now this tesuji no longer works.];
    B[qn];W[rn];B[rm];W[sm];B[rk]
    C[White cannot connect due a shortage of liberties.]
    )
        (;
        W[qn];B[qk];W[rm];B[rl];W[rk];B[ql];W[sl];B[rn];W[sn]
        C[Black has a picnic ko for the life of the corner.];
        B[rj]
        C[At worst, Black prevents a connection.]
        )
    )
)

