(;
AB[cc][cd][de][fe][he][hf][if][ih][jh][ji][kj][pd][nd][nc][mc][ld][pk][nm][no][oo][pp][dp][cp][ep][fp][eo][gq][hq][ip][jp][go][gn][dk]
AW[cb][dc][eb][gc][id][ie][ke][le][me][md][dh][fh][hh][hi][ii][jj][jk][qn][np][mo][lp][jo][io][ho][hp][gp][fq][fo][fn][fm][dn]
C[White is threatening to make a huge left center territory.  So where should Black play?

Source:
    "Correcting the Mistake", Kato Honinbo
    Go World #14, pp. 52-53]
(;
B[en]
C[Pushing here is a mistake.];
W[em]
(;
B[dm]
TR[dn]
C[Black has cut off the marked stone, but ...];
W[dl];B[cm];W[cl]
TR[dn]
C[... White forces on the outside, gladly sacrificing the marked stone.];
B[bn]
LB[bm:A][bl:B][am:C]
C[A must-know tesuji.  If Black plays A instead, White can descend to B with the threat of the big follow-up at C.];
W[bm];B[cn]
LB[bl:A]
TR[dk]
C[Black can now capture at A in sente, but White swallows up the marked stone with a big center left territory.

Black can do better than this sequence.]
)
    (;
    B[cm]
    C[Black can also try this peep, but ...];
    W[dm];B[cn];W[cl]
    LB[co:A]
    C[... White can hane here.  With the weakness at A, Black has problems.]
    )
)
    (;
    B[dm]
    C[This attachment tesuji is correct.]
    (;
    W[cn]
    C[White cannot descend, because ...];
    B[en]
    C[... now this cut works.];
    W[em];B[cm]
    C[White is lost.]
    )
        (;
        W[en]
        C[So White will connect.  But now what is Black's move?]
        (;
        B[cn]
        C[This hane looks obvious, but is a mistake!];
        W[cm]
        C[White's cut works.]
        (;
        B[cl];W[co];B[bm];W[bn]
        C[This fight is not going to end peacefully.  Black wants to avoid this kind of fighting.]
        )
            (;
            B[bn]
            C[Black can give ground here to avoid complications, but this move is a form of submission that Black would also like to avoid.]
            )
        )
            (;
            B[bn]
            C[This tesuji connects Black's stones without compromise!];
            W[cm]
            C[For example ...];
            B[cl];W[cn];B[bm]
            C[A very nice result for Black.]
            )
        )
    )
)

