(;
AB[pd][pf][pj][qj][pp][qo][ro][qq][op][oq][np][no][mo][nm][dd][dj][dp]
AW[nc][jc][lp][lo][lm][mp][nq][mr][or][pr][pq][qp][rp][fq]
C[Black's response to the marked play?

Source:
    Go World #5, Jan-Feb 1978, p. 55 <br>
    Match the Joseki to the Fuseki, Sakiyama Toshio 9p]
TR[fq]
(;
B[fp]
C[Correct.  Black wants to force White to add more stones to the bottom, where White is already overpoweringly strong.   At the same time, Black wants to build up thickness to support a left side moyo.];
W[gp]
(;
B[gq]
C[A nice move to help confine White to the bottom.];
W[ep];B[fo];W[eq];B[eo];W[hq];B[gr];W[hr];B[go];W[hp];B[dq];W[fr];B[er];W[gs];B[do]
C[White's extremely inefficient shape and Black's left side moyo has almost already decided the game in Black's favor.

Of course, White has other variations, but Black's initial crosscut still effectively helps Black to confine White to the bottom.]
)
    (;
    B[fo]
    C[A bit feeble.];
    W[cq]
    LB[cp:A]
    C[White can now counter with a corner invasion here or at A.  White's stones are working much more efficiently, and are limiting Black's left side moyo potential.]
    )
)
    (;
    B[dn]
    C[Too slow.];
    W[cf]
    TR[fq]
    LB[fo:A]
    C[White will probably seize the initiative in the upper left.  Black cannot expect to profit from attacking the marked stone, because White's lower right position is so strong.  And if White can later play A, White's position at the bottom will be much more efficient.]
    )
)

