(;
AB[bc][cc][bd][ec][ed][gc][fe][ff][fg][fh][eh][ae]
AW[cd][dd][ee][ef][dg][eg][dh][dj][ck][be][bf]
C[Black's best endgame sequence?

Source:
    From the endgame volume of Gokyo Seimyo, a nearly 200 year old problem set.]
(;
B[ce]
C[Congratulations if you found and understood the consequences of this sparkling placement tesuji!]
(;
W[cf]
C[White must clamp the Black stone.];
B[af]
C[Black can finish the endgame with the sente push.];
W[ag];B[ad];W[bg]
C[Optimal play for both sides.];
B[dc]
C[Later, connecting in sente is Black's privilege.];
W[de]
C[Note that White needs 2 stones to capture Black's initial placement tesuji.]
)
    (;
    W[de]
    C[White cannot save an endgame point by clamping on this side.];
    B[bg]
    C[The famous nose tesuji erases a lot more of White's territory.]
    (;
    W[cf]
    C[White has no choice but to yield by capturing the stone.];
    B[af]
    C[After Black connects underneath here, White will wind up some 8 points or so worse than the main line!]
    )
        (;
        W[af]
        C[A huge mistake.];
        B[cf]
        C[White's position disintegrates.]
        )
    )
)
    (;
    B[af]
    C[Bad timing.  Even some dan players might carelessly push here.];
    W[ag]
    C[Yes, White must respond.  But ...];
    B[ad];W[bg];B[ce]
    C[... too late.  Black has lost the aji on the left edge.];
    W[de]
    LB[cf:A][dc:B]
    C[After connecting, White saves 1 point by no longer having to capture at A, as in the main line.  In addition, White has gained another point, because later, a play at B is now White's privilege.

Compare this position with the end of the main line to clearly see how White has gained 2 points here.]
    )
)

