(;
AB[sb][rc][rd][re][qf][qg][qh][qi][pi][oi][nj][mj][li][lh][nh][og][nf][mf][lg][lb][la][me][md][lc]
AW[nd][ne][pe][pf][pg][ph][oh][ni][qc][qb][mb][nb]
C[Pro Pair Go Tsumego 4 (Answer)

Presented here is the answer to the 4th tsumego from Michael Redmond 9P's coverage of the challenging tsumego problems featured at the 2016 pro pair go tournament.

Michael mentions that the author of this tsumego, Oba Junya 7P, is well known for his pro level tsumego problems.]
(;
B[ob]
C[Correct.]
(;
W[oc]
C[White is dead in any case, but this variation forces Black to find some clever moves.  In the world of tsumego, that makes this the correct answer.]
(;
B[ma]
C[Correct.  Playing this move now seems a bit counter-intuitive, and I would call this the blind spot built into this tsumego.]
(;
W[oa];B[pb];W[pc];B[na];W[pa];B[ob]
(;
W[nc];B[oe];W[of];B[pd]
C[In this correct answer, Black repeatedly uses eye stealing tesuji to reduce White to a dead shape.]
)
    (;
    W[pb];B[mc];W[nc];B[oe];W[of];B[pd];W[od];B[qd]
    C[Dead.]
    )
)
    (;
    W[pb];B[oa]
    (;
    W[na];B[pd];W[qd];B[oe]
    (;
    W[od];B[qe]
    C[Dead.]
    )
        (;
        W[qe];B[od]
        C[Dead.]
        )
    )
        (;
        W[pd];B[nc]
        (;
        W[qd];B[oe]
        C[Dead.]
        )
            (;
            W[mc];B[qd]
            C[Dead.]
            )
        )
    )
    (;
    W[na];B[pd];W[qd];B[oe];W[od];B[qe];W[pc];B[of];W[oa];B[mc]
    C[Dead.]
    )
)
    (;
    B[pd]
    C[Mistake.  It is still too early to use this tesuji.];
    W[qd];B[oe];W[od];B[qe];W[pc];B[of];W[oa]
    C[Alive.]
    )
    (;
    B[nc]
    C[Mistake.  White has two ways to live.]
    (;
    W[pb];B[oa];W[pa];B[od];W[oe];B[pc];W[pd];B[na];W[oc];B[ma];W[qd]
    C[Alive.]
    )
        (;
        W[oa];B[pb];W[mc]
        C[Alive.]
        )
        (;
        W[mc]
        C[White's mistake];
        B[na]
        C[Dead.]
        )
    )
)
    (;
    W[nc]
    C[This simply dies with not enough space.];
    B[ma];W[na];B[qd];W[pd];B[of];W[oe];B[oc];W[qa];B[pb];W[pc]
    C[Already dead.]
    )
)
    (;
    B[pd]
    C[Mistake.  Although this tsuke is an important tesuji, it must be played with perfect timing.];
    W[qd]
    (;
    B[oe];W[od];B[qe];W[pc];B[of];W[ob]
    C[Alive.]
    )
        (;
        B[ob];W[oc]
        (;
        B[ma];W[oa];B[pb];W[pc];B[na];W[pa];B[ob];W[of]
        (;
        B[od];W[nc]
        C[Alive.]
        )
            (;
            B[nc];W[od]
            C[Alive.]
            )
        )
            (;
            B[oe];W[od];B[qe];W[pc];B[of];W[oa]
            C[Alive.]
            )
        )
    )
)

