(;
GM[1]
SZ[19]
AW[cf][hd][fj][dm]
AB[jp][jd][pj][dj][dp][pd][pp][dd][fp][pn][fd]
LB[cf:1][fd:2][hd:7][fj:5][dm:3][fp:4][pn:6]
C[Problem 17. Black to play.  

Black ignores White's cap at 5 and strengthens his position in the lower left  with 6. How should Black respond to White's invasion at 7 ? ]
(;B[ge]
TE[2]
C[Correct Answer.  

Black should play the diagonal move of 1 and aim to confine White to the top ... ]
;W[he];B[hf];W[if];B[ie];W[hb];B[jb]
LB[ec:B][kc:A][hb:6]
C[Note Black 7. After White 6 in this joseki, White can live on the side by playing at either A or B. Driving White into the corner and confining her there, where she can do the least strategic damage, is the correct choice for Black. ]
;W[ec];B[ed];W[fc];B[dc];W[gd];B[gf];W[db];B[cb]
C[... with the sequence to 15. ]
;W[ea]
C[White lives with 16, but, ... ]
;B[dg]
C[... when Black plays 17, he gets territory on the left side and has foiled White's capping strategy. <= ]
)
(;B[cd]
C[How the game continued.  

Black defended the corner with 1. This was a reasonable move, ... ]
;W[ef]
(;B[gc]
C[... but Black 3 was bad. He did gain some territory in the corner, but ... ]
;W[hc]
C[... it induced White to increase her influence on the right with 4. Black was still left with the problem of how to deal with White's two stones at the top. <= ]
)
(;B[fm]
LB[cd:a]
C[Instead of a in the upper left corner, Black 1 here would also be a good move. <= ]
)
(;B[ge]
C[Black should have simply played at 3 here. <= ]
))
)