(;
AB[co][do][bp][dp][dq][fq][gq]
AW[cj][bn][bo][cn][cp][cq][iq][er]
C[Black plays.]
(;
B[cr]
C[This obvious forcing sequence looks good, but is not Black's best play locally. ];
W[bq];B[br];W[ap];B[dr]
C[Black makes some corner territory by capturing the marked stone.  But the profit isn't much, considering that Black ends in gote.]
TR[er]
)
    (;
    B[bq]
    C[Classic tesuji sequence and shape.

At first glance, this move doesn't seem to work, because the marked stone can help White's 2 stones.]
    TR[er];
    W[cr]
    C[White calls Black's bluff?];
    B[br];W[dr]
    C[White has 5 liberties, Black has 4.  So White wins the semeai, yes?]
    (;
    B[fr]
    C[Simply blocking here, clearly doesn't work.];
    W[bs]
    C[For example ...];
    B[es];W[ar]
    )
        (;
        B[cs]
        C[The hane doesn't work either.];
        W[bs]
        C[This throw-in takes away a critical liberty.];
        B[as];W[ds]
        C[Black has to fight a heavy ko.];
        B[fr];W[ap]
        )
        (;
        B[bs]
        C[Correct!  This counter-intuitive tesuji forces White to make an approach move, so White's initial extra liberty doesn't win the semeai.];
        W[fr]
        C[For example ...];
        B[gr];W[ap];B[fs];W[aq];B[es];W[ar];B[eq]
        LB[as:A][cs:B]
        C[White cannot approach at A or B.]
        )
    )
)

