(;
AB[rr][qq][pp][np][mq][lq][kq][iq][rp][mo][qo]
AW[qr][qs][pq][oq][nq][mr]
C[Black plays.]
(;
B[lr]
C[Vulgar.];
W[ms]
C[White instantly forms a live "comb" shape.];
B[os]
C[For example ...];
W[or]
C[... with outside liberties on both ends of the comb, White can keep 2 eyes.];
B[ls];W[ps]
)
    (;
    B[or]
    C[Better than the previous variation, but ...];
    W[os];B[ns];W[pr]
    C[... Black only has a ko.]
    )
    (;
    B[os]
    C[The only move.]
    (;
    W[or]
    C[But not the best defense.];
    B[ns];W[lr];B[kr]
    C[White dies.]
    )
        (;
        W[ns]
        C[The toughest defense.];
        B[or];W[lr]
        C[Take a hard look at the position.  Can you spot the killing move now?]
        (;
        B[nr]
        C[Bad timing.];
        W[ls]
        C[Black only has a favorable 2 step ko.]
        )
            (;
            B[ls]
            C[A spectacular tesuji!];
            W[kr]
            C[White seems to be able to easily capture the stone for a 2nd eye.];
            B[jr];W[ks];B[nr];W[pr];B[ms];W[ns];B[ms]
            C[Amazingly, Black creates a dead shape.]
            )
        )
    )
)

