[gnugo-devel] endgame mistake

[Arend Bayer]

In this position sent to me by Matthias, no less than 6 mistakes play
together to have gnugo prefer L14 over T2 (playing white):
(I think in deiri counting L14 is worth appr. 2.5 and T2 7.5 points.)

   A B C D E F G H J K L M N O P Q R S T
19 . . . . . . . . . . . X O . . . . . . 19
18 . . O X O O X . X . . X O X X . . . . 18
17 . . O O X X X . . . O X O X . X X . . 17
16 . . . O O X . . X + . X O O X O X X . 16
15 . . X . X O O . . . X . . . X O O X . 15
14 . . . X . . . . O O . X O O X O . O X 14
13 . . O . O . . . O X O X . . O . O . O 13
12 . O . . . . . O X X X . . O . . O O . 12
11 . X O O . . . O X O . X . . . O . O . 11     WHITE (O) has captured 5 stones
10 . X X O . . . O X X O X . X X O O X . 10     BLACK (X) has captured 3 stones
 9 . O O X . X X O X . O O X . . O X X . 9
 8 . O X X X X O X O O . O X . . X X . . 8
 7 . O O O X O O X . . O X . . . . . . . 7
 6 . X O X O O . . O . O X . X . X O . . 6
 5 X . X X . O O X O O . X X . X . . . . 5
 4 . X O X X X O O X X X X . X O X X X . 4
 3 . O O X . O . . O X X O . O O O O X . 3
 2 . O X X . . O O . O X O . . . . . O . 2
 1 . . . . . . . . O . O . . . . . . . . 1
   A B C D E F G H J K L M N O P Q R S T

1) L14 has territorial value 3.0 instead of 2.5
2) L14 gets a bogus shape bonus from CC81
3) L14 gets a pretty high "connects strings" bonus which seems inappropriate
here
4) gnugo misses that T2 makes R2 territory
5) doesn't understand that the followup of T2 at T3 is sente (and should thus
be counted with full value instead of only 50%)
6) the reverse followup-value of T2 should be around 7 pts but is assumed to
be 3 pts

It might actually be worth creating separate tests to single out a few of
this problems.
2), 4) and 6) should be easy to fix.

Arend


Index: regression/endgame.tst
===================================================================
RCS file: /cvsroot/gnugo/gnugo/regression/endgame.tst,v
retrieving revision 1.39
diff -u -p -r1.39 endgame.tst
--- regression/endgame.tst      24 Jan 2004 04:04:57 -0000      1.39
+++ regression/endgame.tst      6 Apr 2004 18:14:15 -0000
@@ -200,6 +200,10 @@ loadsgf games/nngs/gnugo-3.3.21-joshj-20
 900 reg_genmove white
 #? [J19|K19|K18]

+loadsgf games/yagr-eddyy.sgf 198
+910 reg_genmove white
+#? [T2]
+

 ############ End of Tests #################

Index: regression/games/yagr-eddyy.sgf
===================================================================
RCS file: regression/games/yagr-eddyy.sgf
diff -N regression/games/yagr-eddyy.sgf
--- /dev/null   1 Jan 1970 00:00:00 -0000
+++ regression/games/yagr-eddyy.sgf     6 Apr 2004 18:14:29 -0000
@@ -0,0 +1,296 @@
+(;GM[1]FF[4]CA[UTF-8]AP[CGoban:2]ST[2]
+RU[AGA]SZ[19]KM[0.50]TM[600]OT[20/120 Canadian]
+PW[yagr]PB[eddyy]WR[9k]BR[12k]DT[2004-04-06]PC[The Kiseido Go Server (KGS) at 
http://kgs.kiseido.com/]C[yagr [9k\]: GTP Engine for yagr (white): GNU Go 
version 3.5.4
+]RE[W+67.50]
+;B[dp]BL[596.133]CR[dp]
+;W[dd]WL[599.845]CR[dd]
+;B[pp]BL[594.033]CR[pp]
+;W[pd]WL[599.591]CR[pd]
+;B[qf]BL[592.137]CR[qf]
+;W[nd]WL[598.908]CR[nd]
+;B[rd]BL[590.362]CR[rd]
+;W[qn]WL[598.39]CR[qn]
+;B[ql]BL[588.75]CR[ql]
+;W[nq]WL[596.397]CR[nq]
+;B[pn]BL[586.724]CR[pn]
+;W[qh]WL[593.18]CR[qh]
+;B[qc]BL[583.694]CR[qc]
+;W[qe]WL[591.729]CR[qe]
+;B[re]BL[581.968]CR[re]
+;W[pf]WL[589.862]CR[pf]
+;B[qd]BL[580.722]CR[qd]
+;W[qq]WL[587.857]CR[qq]
+;B[qp]BL[578.854]CR[qp]
+;W[pq]WL[583.561]CR[pq]
+;B[rq]BL[574.762]CR[rq]
+;W[fq]WL[580.219]CR[fq]
+;B[hq]BL[573.317]CR[hq]
+;W[cn]WL[577.136]CR[cn]
+;B[fp]BL[571.545]CR[fp]
+;W[cq]WL[573.478]CR[cq]
+;B[dq]BL[570.812]CR[dq]
+;W[cp]WL[567.599]CR[cp]
+;B[dn]BL[570.104]CR[dn]
+;W[gp]WL[561.394]CR[gp]
+;B[gq]BL[567.436]CR[gq]
+;W[rr]WL[557.755]CR[rr]
+;B[rp]BL[561.623]CR[rp]
+;W[dm]WL[554.583]CR[dm]
+;B[co]BL[558.817]CR[co]
+;W[bo]WL[547.733]CR[bo]
+;B[do]BL[558.014]CR[do]
+;W[cm]WL[543.174]CR[cm]
+;B[cr]BL[550.133]CR[cr]
+;W[fo]WL[540.392]CR[fo]
+;B[ep]BL[546.918]CR[ep]
+;W[go]WL[536.968]CR[go]
+;B[kq]BL[543.178]CR[kq]
+;W[di]WL[534.13]CR[di]
+;B[fc]BL[526.189]CR[fc]
+;W[fe]WL[531.168]CR[fe]
+;B[id]BL[517.165]CR[id]
+;W[kc]WL[527.948]CR[kc]
+;B[db]BL[515.072]CR[db]
+;W[cc]WL[523.775]CR[cc]
+;B[ib]BL[507.667]CR[ib]
+;W[br]WL[519.431]CR[br]
+;B[dr]BL[504.445]CR[dr]
+;W[cb]WL[515.646]CR[cb]
+;B[df]BL[496.783]CR[df]
+;W[eg]WL[508.638]CR[eg]
+;B[ce]BL[492.159]CR[ce]
+;W[cg]WL[500.59]CR[cg]
+;B[pc]BL[479.466]CR[pc]
+;W[pe]WL[493.847]CR[pe]
+;B[nb]BL[476.553]CR[nb]
+;W[if]WL[488.755]CR[if]
+;B[ke]BL[474.309]CR[ke]
+;W[rf]WL[480.982]CR[rf]
+;B[rg]BL[472.053]CR[rg]
+;W[qg]WL[476.197]CR[qg]
+;B[sf]BL[471.154]CR[sf]
+;W[eb]WL[471.735]CR[eb]
+;B[ec]BL[467.536]CR[ec]
+;W[dc]WL[459.815]CR[dc]
+;B[ee]BL[463.98]CR[ee]
+;W[ed]WL[451.964]CR[ed]
+;B[fd]BL[462.442]CR[fd]
+;W[fb]WL[445.241]CR[fb]
+;B[gb]BL[457.247]CR[gb]
+;W[ge]WL[438.379]CR[ge]
+;B[gc]BL[452.574]CR[gc]
+;W[oc]WL[433.169]CR[oc]
+;B[ob]BL[450.003]CR[ob]
+;W[in]WL[429.343]CR[in]
+;B[lo]BL[447.575]CR[lo]
+;W[no]WL[423.971]CR[no]
+;B[nn]BL[445.678]CR[nn]
+;W[op]WL[416.802]CR[op]
+;B[oo]BL[444.092]CR[oo]
+;W[lr]WL[411.719]CR[lr]
+;B[kr]BL[438.041]CR[kr]
+;W[jl]WL[405.172]CR[jl]
+;B[ld]BL[433.745]CR[ld]
+;W[mc]WL[398.979]CR[mc]
+;B[lc]BL[431.887]CR[lc]
+;W[mb]WL[390.878]CR[mb]
+;B[nc]BL[428.906]CR[nc]
+;W[rh]WL[381.411]CR[rh]
+;B[rj]BL[421.802]CR[rj]
+;W[sg]WL[375.705]CR[sg]
+;B[od]BL[418.411]CR[od]
+;W[md]WL[367.565]CR[md]
+;B[oe]BL[416.986]CR[oe]
+;W[mf]WL[359.813]CR[mf]
+;B[lb]BL[412.181]CR[lb]
+;W[kg]WL[354.979]CR[kg]
+;B[lf]BL[409.975]CR[lf]
+;W[nf]WL[348.349]CR[nf]
+;B[of]BL[408.037]CR[of]
+;W[og]WL[342.715]CR[og]
+;B[lg]BL[376.248]CR[lg]
+;W[nh]WL[338.096]CR[nh]
+;B[li]BL[373.96]CR[li]
+;W[ji]WL[334.978]CR[ji]
+;B[dk]BL[348.652]CR[dk]
+;W[ck]WL[329.53]CR[ck]
+;B[cj]BL[339.487]CR[cj]
+;W[dj]WL[321.103]CR[dj]
+;B[cl]BL[337.879]CR[cl]
+;W[bk]WL[307.24]CR[bk]
+;B[dl]BL[335.871]CR[dl]
+;W[bl]WL[296.898]CR[bl]
+;B[el]BL[333.839]CR[el]
+;W[kn]WL[291.348]CR[kn]
+;B[em]BL[330.769]CR[em]
+;W[en]WL[282.341]CR[en]
+;B[ho]BL[324.815]CR[ho]
+;W[hp]WL[271.087]CR[hp]
+;B[ip]BL[315.021]CR[ip]
+;W[fm]WL[261.675]CR[fm]
+;B[fl]BL[311.665]CR[fl]
+;W[fn]WL[252.292]CR[fn]
+;B[hl]BL[309.496]CR[hl]
+;W[io]WL[241.823]CR[io]
+;B[bp]BL[287.729]CR[bp]
+;W[hj]WL[235.029]CR[hj]
+;B[ik]BL[282.097]CR[ik]
+;W[gl]WL[226.861]CR[gl]
+;B[gk]BL[277.354]CR[gk]
+;W[gm]WL[211.742]CR[gm]
+;B[fk]BL[276.13]CR[fk]
+;W[hk]WL[204.084]CR[hk]
+;B[hm]BL[264.683]CR[hm]
+;W[iq]WL[191.042]CR[iq]
+;B[jp]BL[245.586]CR[jp]
+;W[hr]WL[178.726]CR[hr]
+;B[ir]BL[226.548]CR[ir]
+;W[gr]WL[167.964]CR[gr]
+;B[mo]BL[225.643]CR[mo]
+;W[bq]WL[149.222]CR[bq]
+;B[bn]BL[214.868]CR[bn]
+;W[bm]WL[143.792]CR[bm]
+;B[ao]BL[213.855]CR[ao]
+;W[jr]WL[139.064]CR[jr]
+;B[bj]BL[210.235]CR[bj]
+;W[ci]WL[126.352]CR[ci]
+;B[bi]BL[201.223]CR[bi]
+;W[bh]WL[117.774]CR[bh]
+;B[jq]BL[198.267]CR[jq]
+;W[is]WL[101.349]CR[is]
+;B[np]BL[196.428]CR[np]
+;W[lq]WL[92.816]CR[lq]
+;B[lp]BL[188.696]CR[lp]
+;W[oq]WL[87.132]CR[oq]
+;B[nj]BL[180.655]CR[nj]
+;W[kj]WL[83.234]CR[kj]
+;B[lj]BL[177.537]CR[lj]
+;W[lk]WL[79.086]CR[lk]
+;B[mk]BL[172.784]CR[mk]
+;W[ll]WL[74.375]CR[ll]
+;B[ml]BL[170.84]CR[ml]
+;W[ks]WL[62.96]CR[ks]
+;B[kh]BL[156.415]CR[kh]
+;W[qj]WL[60.015]CR[qj]
+;B[qk]BL[153.841]CR[qk]
+;W[jf]WL[47.76]CR[jf]
+;B[jg]BL[145.971]CR[jg]
+;W[ig]WL[44.882]CR[ig]
+;B[jh]BL[144.952]CR[jh]
+;W[pk]WL[41.945]CR[pk]
+;B[ih]BL[142.383]CR[ih]
+;W[hh]WL[34.144]CR[hh]
+;B[ii]BL[138.834]CR[ii]
+;W[hi]WL[31.077]CR[hi]
+;B[ij]BL[137.661]CR[ij]
+;W[pi]WL[28.693]CR[pi]
+;B[oj]BL[127.814]CR[oj]
+;W[pj]WL[27.222]CR[pj]
+;B[pl]BL[126.723]CR[pl]
+;W[il]WL[25.927]CR[il]
+;B[jj]BL[104.787]CR[jj]
+;W[ma]WL[23.897]CR[ma]
+;B[la]BL[58.508]CR[la]
+;W[jo]WL[22.251]CR[jo]
+;B[kp]BL[56.452]CR[kp]
+;W[ri]WL[20.222]CR[ri]
+;B[rk]BL[54.94]CR[rk]
+;W[kk]WL[18.846]CR[kk]
+;B[lm]BL[46.559]CR[lm]
+;W[km]WL[16.951]CR[km]
+;B[ln]BL[45.345]CR[ln]
+;W[kf]WL[14.638]CR[kf]
+;B[ki]BL[43.536]CR[ki]
+;W[sr]WL[12.549]CR[sr]C[Dieser Zug kommt viel zu sp??t, bspw. ist 198 genau 2 
Punkte in Nachhand, und damit deutlich kleiner.
+
+Das gleiche gibts auch mit einem wei??en Stein auf r2. Hilft das, wenn ich 
sowas noch raussuche?]
+;B[sq]BL[41.709]CR[sq]
+;W[ok]WL[11.42]CR[ok]
+;B[nk]BL[39.852]CR[nk]
+;W[ol]WL[10.385]CR[ol]
+;B[om]BL[38.869]CR[om]
+;W[er]WL[9.322]CR[er]
+;B[es]BL[33.727]CR[es]
+;W[fs]WL[7.853]CR[fs]
+;B[ds]BL[32.789]CR[ds]
+;W[he]WL[6.371]CR[he]
+;B[ie]BL[27.326]CR[ie]
+;W[je]WL[4.635]CR[je]
+;B[kd]BL[25.451]CR[kd]
+;W[jd]WL[3.028]CR[jd]
+;B[jc]BL[24.434]CR[jc]
+;W[hd]WL[1.455]CR[hd]
+;B[ic]BL[22.814]CR[ic]
+;W[mh]WL[119.77]OW[19]CR[mh]
+;B[lh]BL[21.291]CR[lh]
+;W[se]WL[118.639]OW[18]CR[se]
+;B[sd]BL[19.981]CR[sd]
+;W[eq]WL[117.528]OW[17]CR[eq]
+;B[bs]BL[14.687]CR[bs]
+;W[jk]WL[116.429]OW[16]CR[jk]
+;B[mq]BL[4.431]CR[mq]
+;W[mr]WL[115.272]OW[15]CR[mr]
+;B[fa]BL[115.359]OB[19]CR[fa]
+;W[da]WL[114.475]OW[14]CR[da]
+;B[oi]BL[84.775]OB[18]CR[oi]
+;W[hc]WL[113.362]OW[13]CR[hc]
+;B[hb]BL[83.374]OB[17]CR[hb]
+;W[sj]WL[112.053]OW[12]CR[sj]
+;B[sk]BL[81.995]OB[16]CR[sk]
+;W[si]WL[111.071]OW[11]CR[si]
+;B[am]BL[62.702]OB[15]CR[am]
+;W[ai]WL[108.584]OW[10]CR[ai]
+;B[ak]BL[59.301]OB[14]CR[ak]
+;W[aj]WL[106.494]OW[9]CR[aj]
+;B[an]BL[57.831]OB[13]CR[an]
+;W[al]WL[105.251]OW[8]CR[al]
+;B[mi]BL[47.137]OB[12]CR[mi]
+;W[ar]WL[104.367]OW[7]CR[ar]
+;B[bo]BL[28.738]OB[11]CR[bo]
+;W[ap]WL[103.582]OW[6]CR[ap]
+;B[aq]BL[27.68]OB[10]CR[aq]
+;W[qm]WL[102.92]OW[5]CR[qm]
+;B[pm]BL[20.541]OB[9]CR[pm]
+;W[ap]WL[102.234]OW[4]CR[ap]
+;B[hf]BL[17.968]OB[8]CR[hf]
+;W[eo]WL[99.462]OW[3]CR[eo]
+;B[aq]BL[16.303]OB[7]CR[aq]
+;W[hg]WL[96.829]OW[2]CR[hg]
+;B[as]BL[14.59]OB[6]CR[as]
+;W[oh]WL[95.944]OW[1]CR[oh]
+;B[mg]BL[11.242]OB[5]CR[mg]
+;W[ng]WL[120]OW[20]CR[ng]
+;B[me]BL[10.092]OB[4]CR[me]
+;W[ne]WL[119.454]OW[19]CR[ne]
+;B[le]BL[9.599]OB[3]CR[le]
+;W[oc]WL[118.68]OW[18]CR[oc]
+;B[od]BL[7.869]OB[2]CR[od]
+;W[oe]WL[118.092]OW[17]CR[oe]
+;B[oc]BL[4.626]OB[1]CR[oc]
+;W[nl]WL[117.512]OW[16]CR[nl]
+;B[nm]BL[120]OB[20]CR[nm]
+;W[na]WL[116.895]OW[15]CR[na]
+;B[oa]BL[118.546]OB[19]CR[oa]
+;W[mp]WL[116.328]OW[14]CR[mp]
+;B[no]BL[116.861]OB[18]CR[no]
+;W[mq]WL[115.747]OW[13]CR[mq]
+;B[ga]BL[108.835]OB[17]CR[ga]
+;W[ea]WL[115.147]OW[12]CR[ea]
+;B[gf]BL[105.175]OB[16]CR[gf]
+;W[de]WL[114.281]OW[11]CR[de]
+;B[ef]BL[103.638]OB[15]CR[ef]
+;W[ff]WL[112.782]OW[10]CR[ff]
+;B[cf]BL[98.101]OB[14]CR[cf]
+;W[bd]WL[111.23]OW[9]CR[bd]
+;B[dg]BL[91.477]OB[13]CR[dg]
+;W[fg]WL[110.237]OW[8]CR[fg]
+;B[]BL[62.702]OB[12]
+;W[sf]WL[109.651]OW[7]CR[sf]
+;B[]BL[62.702]OB[11]
+;W[ko]WL[109.171]OW[6]CR[ko]
+;B[]BL[62.702]OB[10]
+;W[ni]WL[108.635]OW[5]CR[ni]
+;B[]BL[62.702]OB[9]
+;W[gd]WL[108.161]OW[4]CR[gd]
+;B[]BL[62.702]OB[8]
+;W[]WL[108.161]OW[3]TW[aa][ba][ca][ab][bb][db][ac][bc][ad][cd][ae][be][ce][ee][af][bf][cf][df][ef][gf][hf][of][qf][ag][bg][dg][gg][pg][rg][ah][ch][dh][eh][fh][gh][ph][sh][bi][ei][fi][gi][qi][bj][cj][ej][fj][gj][ak][dk][ek][fk][gk][cl][dl][el][fl][hl][kl][em][hm][im][jm][gn][hn][jn][ho][gq][hq][fr][ir][nr][or][pr][qr][gs][hs][js][ls][ms][ns][os][ps][qs][rs][ss]TB[ha][ia][ja][ka][pa][qa][ra][sa][jb][kb][pb][qb][rb][sb][kc][rc][sc][ji][mj][rl][sl][mm][qm][rm][sm][mn][on][qn][rn][sn][po][qo][ro][so][ap][cp][sp][bq][cq][ar][br][cs])