(;
AB[bd][cd][dd][ed][ae][ee][ef][eg][bi][ci][di][aj][bk]
AW[ac][bc][cc][dc][ec][ad][fd][fe][bj][cj][ck][cl]
C[White plays]
(;
W[ah]
C[Correct!  An easy move to overlook.  White makes a double threat of capturing the stone above, and the 2 stones below.];
B[ai]
C[Black can still connect, but ...];
W[be]
C[White ruins much of Black's inside territory.]
)
    (;
    W[bl]
    C[Sealing off the left side seems automatic.];
    B[ai]
    C[After Black connects here, White may realize that the 1st move atari was a mistake!]
    )
)

