(;
AB[fb][fc][fd][bc][cc][dc][bd][ed][pd][pf][qf][rf][ph][ol][ql][mm][mn][mo][mp][qn][rn][bo][co][oo][op][dp][bq][cq][eq][er][lq][nq][nr][dr][or]
AW[gb][gc][gd][oc][pc][qc][cd][dd][ld][od][be][de][ee][fe][qe][re][cf][dj][bn][cn][dn][nn][no][np][on][do][qo][ro][bp][ep][fp][fq][fr][oq][pq][pr][ps][es]
PL[W]
C[Black plays.  Which play has a different effective value than the others?

Source:
    "Odd Man Out", Ogawa Tomoko 4P and James Davies
    Go World #21, pp. 57-59]
LB[ga:A][se:B][so:C][an:D]
(;
B[ga]
C[Double sente.];
W[ha];B[fa];W[hb]
C[Similarly, if White hanes 1st from the starting position, White reduces the corner by 2 points in sente.

So A is 4 points in double sente.]
LB[ga:A]
)
    (;
    B[an]
    C[Double sente.];
    W[am];B[ao];W[bm]
    C[Note that if White plays the hane 1st, Black has to answer at the marked point.  Then White tenukis.  White reduces the corner by 2 points in sente.

So D is similar to the top left.]
    LB[an:D]
    TR[cp]
    )
    (;
    B[so]
    C[Double sente.];
    W[sp];B[sn];W[rp]
    C[If White hanes 1st, then White reduces Black's right side by 2 points in sente.

So C is also similar to the top left.]
    LB[so:C]
    )
    (;
    B[se]
    C[This hane looks like a double sente play, but is not in the same class as the other 3 corners.];
    W[sd];B[sf];W[qd]
    TR[pe][of]
    C[Black keeps sente, but as a result of defending, White now has the marked follow-ups.

See the next variation for White playing the hane 1st.]
    )
    (;
    W[sf]
    C[White's hane here also leaves a problem.];
    B[sg];W[se];B[rg]
    C[White reduces the right side by 2 points in sente, but the value is less, because now Black A becomes sente, threatening B.]
    LB[pe:A][qd:B]
    )
)

