Re: [computer-go] How come Gnu managed to lose to indigo?

[Gunnar Farnebäck <gunnar@xxxxxxxxxxxxxx>]

Petri wrote:
> Any plausibel explanation why GnuGo lost to indigo in 2004 Computer
> Olympiad? I played quickly (well I played quickly, not the indigo) and
> I was able to pull about 120 pt win against it. While with Gnu Go I
> occasionally lose to it but usesually win by 20-30 points?

You could say that GNU Go was too greedy plus it misread life and
death and semeai too many times. I have included the game record
below, so see for yourself.

> Gnu Go is much stronger than indigo tactically. And even in
> "WholeBordVision" it does better job. Indigo allows it groups to be
> enclosed far too easily. So is ther some plausible explanation. Like
> Gnu Go is too passive and does not get advantage it deserves because
> it does not challenge its' lesser abled opponet into a fight?.

No, I wouldn't say GNU Go was too passive in this game, rather the
opposite. The opening and early midgame saw a fair share of bad moves
from both programs but was not very dramatic. After 107 moves GNU Go
(black) was clearly ahead and would have had an easy win if it only
passively defended the big area on the left. Instead it attacked, cut
off, and killed white's center group. That was where the trouble
started.

White started thrashing around but GNU Go, confident it was still
dead, ignored it at multiple times to pick up points elsewhere,
including cutting off another group. Unfortunately white was allowed
to pick up too much aji, including cutting black's stones apart and
eventually GNU Go found itself involved in less favorable semeais
which it also misread multiple times. Now it was instead white that
played tenuki and took back points in the upper and lower right while
GNU Go was busy playing bad semeai moves. When everything had settled
white had managed to bring out the big dragon and kill one for black,
getting lots of points in the upper left.

GNU Go countered by killing the lower left corner but was still
behind. Later (move 249) GNU Go miscounted and offered white a
slightly disadvantageous exchange but white did some bad misreading
and let black win both fights with only a small compensation
elsewhere. This let black catch up. To make matters worse for white it
goofed badly at move 264 and in the following moves black was allowed
to walk into the white territory at the top. After the final endgame
moves GNU Go was ahead and won by 12.5 points...

...but the lower left corner was no longer dead after black filled a
liberty with the last move. White can make life, or at black's choice,
get a ko for the life and death of both groups. The jury decided to
give the win to white.

/Gunnar

(;GM[1]FF[4]
SZ[19]HA[0]KM[6.5]
PW[Indigo]PB[GNU Go]DT[2004-07-06]GN[Indigo (W) vs. GNU Go (B)]
RE[W+Resign]
TM[60:00]RU[Chinese]
C[GNU Go 3.5.8 Random Seed 1089145585 level 12
Indigo used 47:29 minutes
GNU Go used 12:23 minutes]
;B[qd];W[cp];B[pp];W[dc];B[ph];W[oc];B[ld];W[jp];B[de];W[fd];B[cc]
;W[cb];B[cd];W[qn];B[bb];W[eq];B[cj];W[qb];B[ql];W[lb];B[pn];W[oe]
;B[qo];W[nq];B[pf];W[pr];B[cm];W[jd];B[ff];W[pm];B[qm];W[rn];B[om]
;W[on];B[pl];W[lf];B[gq];W[db];B[go];W[kc];B[he];W[ro];B[rp];W[hd]
;B[jr];W[lp];B[jn];W[hp];B[gp];W[lr];B[iq];W[hq];B[ip];W[io];B[ho]
;W[rr];B[jo];W[hr];B[gr];W[jq];B[ir];W[cr];B[em];W[ge];B[gh];W[gf]
;B[gg];W[rm];B[jg];W[rl];B[rk];W[lh];B[ji];W[og];B[pg];W[lj];B[jk]
;W[of];B[pj];W[jf];B[oo];W[nn];B[no];W[hf];B[bo];W[bp];B[mn];W[nm]
;B[mp];W[mq];B[cn];W[lo];B[nl];W[mm];B[ln];W[ll];B[lm];W[ml];B[nk]
;W[mo];B[kl];W[lk];B[ko];W[np];B[nh];W[oh];B[oi];W[ig];B[kg];W[ih]
;B[lg];W[jh];B[kh];W[ki];B[mh];W[li];B[mf];W[jj];B[ii];W[ij];B[hi]
;W[kf];B[mg];W[il];B[jl];W[ik];B[md];W[me];B[ne];W[im];B[in];W[jm]
;B[km];W[gk];B[le];W[ek];B[hj];W[eh];B[eg];W[ch];B[mb];W[dg];B[ob]
;W[gl];B[df];W[fi];B[di];W[dh];B[bg];W[ck];B[bk];W[nc];B[dk];W[mc]
;B[rc];W[eo];B[pb];W[lc];B[od];W[dl];B[dj];W[el];B[dm];W[nd];B[pd]
;W[cl];B[bl];W[bh];B[fn];W[bf];B[bi];W[ah];B[fh];W[ei];B[ba];W[ej]
;B[gj];W[qq];B[ee];W[fe];B[hk];W[gm];B[cf];W[be];B[cg];W[qp];B[po]
;W[bd];B[nb];W[bc];B[ap];W[pc];B[qc];W[rb];B[ar];W[ag];B[er];W[pe]
;B[sb];W[re];B[qe];W[qf];B[sc];W[qg];B[qh];W[bq];B[aq];W[rh];B[sk]
;W[qi];B[pi];W[dq];B[do];W[ie];B[ri];W[kp];B[hm];W[hl];B[kr];W[hn]
;B[io];W[gn];B[kk];W[fo];B[fm];W[ai];B[aj];W[bs];B[fl];W[fk];B[ls]
;W[br];B[ds];W[al];B[bj];W[co];B[bm];W[kj];B[kn];W[ms];B[ks];W[ke]
;B[sl];W[sh];B[si];W[pq];B[sm];W[rg];B[sp];W[op];B[pm];W[mi];B[se]
;W[sf];B[sd];W[ni];B[ma];W[rq];B[so];W[nj];B[oj];W[mk];B[la];W[kb]
;B[ka];W[jb];B[ja];W[fb];B[ib];W[kq];B[ic];W[kd];B[nf];W[me];B[ng]
;W[sq];B[sn];W[ha];B[hb];W[ga];B[ia];W[gb];B[hc];W[gc];B[id];W[jc]
;B[ci];W[];B[]C[The lower left corner is unsettled. The jury decided
that white won the game.])
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