(;
AB[pd][oc][qf]
AW[nc][nd][lc][kc]
PL[W]
C[Play a couple moves to reach the problem awaiting Black.

Source:  position from a simul game with Kim Myungwan 9P against a mid-dan player with a 4 stone handicap.];
W[pe]
C[Cool move.  Black had a look of bemusement upon seeing this move.];
B[qe]
C[Black slammed this stone down with a look of "thank you" on his face.];
W[of]
C[Even cooler move.

Now Black's look of bemusement became even bigger.  What is White doing?!

After about 20 seconds, Black tenukis.];
W[qc]
C[After a few intermediate moves, White comes back here to invade.

What does Black do now?]
(;
B[pc]
C[Without realizing the danger, or asking himself why a 9 dan pro would "waste" a stone in the corner, Black quickly slammed this stone down!

Big mistake.];
W[qd]
C[Uh, oh.  Now Black starts to see a problem and so took a full minute to consider a response, and then ...];
B[qb]
C[... _gently_ placed this stone.];
W[rb];B[pb];W[ra]
C[Nice move.];
B[rd];W[rc];B[se]
C[Up to this move, Black still seemed hopeful.  Maybe the corner is a ko?];
W[od]
C[White calmly removes a liberty here, and after another few seconds Black tenukis.  Only now does Black see that the corner is dead!]
(;
B[nb]
C[For example ...];
W[mb];B[oa];W[qa];B[pa];W[ma];B[sc];W[na]
)
    (;
    B[sc]
    C[No better.];
    W[nb]
    C[Both sides have 3 liberties, but Black has to make an approach move, so ...];
    B[sb];W[ob]
    C[... Black dies from a liberty shortage.]
    )
)
    (;
    B[qd]
    C[After the game, Kim Myungwan pointed out that Black needed to fall back to defend the corner.];
    W[ob];B[pc]
    )
    (;
    B[ob]
    C[As an exercise, the reader can work out what White can do, if Black tries this descent.]
    )
)

