(;
GM[1]
SZ[19]
AW[dd][jd][nc][dp][nq][no][pr]
AB[pd][pf][kp][pp][pn][qq][pj]
LB[kr:A][kp:7][dp:4][dd:2][jd:14][nc:12][pd:1][pf:13][pj:5][pn:9]
LB[pp:3][qq:11][no:8][nq:6][pr:10]
C[Problem 18. Black to play.  

After Black 11, White has neglected to complete the joseki by sliding to A. How should Black punish White for this omission ? ]
(;B[mp]
TE[2]
C[Correct Answer.  

Black should peep with 1 ... ]
;W[np];B[mq]
C[... and rob White of her eye shape with 3. ]
(;W[nr]
C[If White descends to 4, ... ]
;B[gq]
C[... Black will take up a position at the bottom by extending to 5. <= ]
)
(;W[hp]
C[If White 4 here, ... ]
;B[nr]
C[... Black will hane at 5, leaving the white stones eyeless and under a severe attack. <= ]
))
(;B[cj]
C[Failure.  

Black would like to establish a presence on the left by playing at 1, but ... ]
;W[kr]
C[... White would then be able to settle her stones at the bottom by sliding to 2. <= ]
)
)