(;
AB[bo][ap][bq][cq][cp][eq]
AW[co][fp][fr][br][cs][dp][fq][cn][bn][eo]
C[Black plays.

The solution to "Yilun Yang's November Easy Life and Death Puzzle", from the 2009-Nov-09 American Go E-Journal, seems to have the incorrect move order.  What do you think?

Analysis:
    Myron Souris]
(;
B[bs]
C[Mr. Yang's intended solution for reaching a ko.]
(;
W[as];B[ar]
C[Mr. Yang's analysis, which stops here, gives the result as a ko.

But ...];
W[ds]
C[... doesn't this move kill Black outright?

Perhaps Mr. Yang missed this move?]
(;
B[bs];W[cr]
C[White can simply ignore the ko.];
B[es];W[dr]
C[Black cannot keep White from connecting out.  Black dies having only one eye.]
)
    (;
    B[cr]
    C[Also fails.];
    W[bs];B[es];W[dr]
    C[Again, White connects out and Black dies.]
    )
)
    (;
    W[cr]
    C[Mr. Yang also gives this (inferior) defense, which does give Black a ko.];
    B[dr];W[ds];B[es];W[as];B[ar]
    C[Ko.

And Black will wind up taking the ko 1st because of the internal ko threat at E2.]
    )
)
    (;
    B[ar]
    C[Fails];
    W[bs]
    C[White takes the vital point.  Black has nothing.]
    )
    (;
    B[dr]
    C[Mr. Yang doesn't mention this move, which appears to be the only move for Black to reach a ko.];
    W[ds];B[es]
    (;
    W[er];B[bs]
    C[Now this throw-in works.]
    (;
    W[fs]
    C[Best play for both sides.];
    B[ar]
    C[White can no longer kill by connecting out, due to a shortage of liberties.];
    W[as]
    C[But White is happy to take the ko 1st.]
    )
        (;
        W[as]
        C[Inferior];
        B[ar];W[aq];B[cr];W[fs];B[ar]
        C[Black takes the ko 1st.]
        )
    )
        (;
        W[bs]
        C[White doesn't have time for this defense.];
        B[er]
        C[Black lives outright.]
        )
    )
)

