(;
AB[hc][dd][pd][cf][qg][jp][np][nq][op][fq]
AW[pb][jc][mc][cn][qn][dp][qp][oq][pq][lr]
C[Black's response to the marked invasion?

Source:
    AGJ Vol. 35, No. 1, pp. 24-25
    Translation from Baduk Monthly, August 1998]
TR[lr]
(;
B[mr]
C[Black attacks, declaring that White should not be able to escape easily from Black's territory.  But this attachment is an overplay.]
(;
W[lp]
C[With this important jump, White tests Black's response.]
(;
B[lo]
C[If Black blocks, ...];
W[iq]
C[... the attack goes nowhere after White jumps here.]
(;
B[kp];W[ip]
C[After White stands up here, Black's marked stone is cut off.  And White still has aji with the 2 stones to the right.]
TR[fq]
)
    (;
    B[jq]
    C[If Black descends ...];
    W[jr];B[kr]
    C[... and then wedges here, ...];
    W[kq]
    C[... White will capture a stone in sente.];
    B[ir];W[ks];B[ip]
    C[Black protects the stones to the left, but ...];
    W[mo]
    C[... with this hane, Black's marked stones are floating without a base.]
    TR[np][nq][op][mr]
    )
)
    (;
    B[jq]
    C[If Black plays solidly by descending, ...]
    (;
    W[ln]
    C[... Black is hoping that White jumps out to safety, after which ...];
    B[kr]
    C[... Black connects all the bottom stones and White's group is floating.]
    )
        (;
        W[jr]
        C[... White avoids Black's plan with this attachment.];
        B[ir];W[ln];B[kr];W[nm]
        C[Now White can play this outside enclosing move in sente.]
        PL[B]
        (;
        W[kq]
        C[If Black tenukis, White's atari creates a big problem.];
        B[js];W[ls]
        C[Black is no longer connected.]
        )
            (;
            B[lq]
            C[Because of the previous variation, Black must connect in gote.  This result is a success for White.]
            )
        )
    )
)
    (;
    W[iq]
    C[Playing here first is bad timing.];
    B[lq]
    C[A good move.];
    W[ip]
    C[Now White standing up here is different from the previous variation, because Black does not have to reinforce the stones to the right.];
    B[dq]
    C[So without worrying, Black can concentrate on just helping the stone to the left with this attachment.

White is not dissatisfied, but has missed an opportunity with this variation.]
    )
)
    (;
    B[pp]
    C[Testing White here is correct.];
    W[qq]
    C[Assume that White connects.  Now what does Black do?];
    B[kq]
    C[Black want to build thickness, but this move is questionable for this situation.

Note:  Next week's problem will show what Black should play here instead.];
    W[lq];B[lp];W[nr]
    C[Up to here is a standard sequence, but Black loses too much territory in return for building center thickness in sente.  Black needs a good outside reason to play this way.]
    )
)

