hyperpape wrote:
Bill Spight wrote:
In part it depends upon what you mean by perfect play. It is not at all unusual for a pro to choose an inferior play in the endgame that does not end up costing the game, or costing a point.
What do you mean by this? Inferior in the sense that it would cost a point with the proper response, or inferior in the sense that it loses a fraction of a point, but that doesn't actually make one points worth of difference?
I mean inferior play, no matter how slight the theoretical cost.
Quote:
Quote:
In part it depends upon time limits. In the late 19th century top level pros played nearly flawless endgames, in the sense of not giving up a point. In the early 20th century, after the introduction of time limits, top level pros rarely gave up a point with plays that gained less than 3 points. With today's quick time limits, even top level pros give up points to perfect play fairly late in the game.
Interesting. Do today's quick time limits include the Japanese 8 hour matches, the 3 hour matches, or just the shorter games?
I had one day games in mind.

I went looking and found an inaccuracy in the first game I played through, by one of the world's top players. If it made a difference, he would very probably have made the correct play, but I have found similar errors when it mattered, by top players.
(;ST[2]GM[1]CA[ISO8859-1]FF[4]AP[GOWrite:2.2.21]SZ[19]PM[0]BR[9d]WR[9d]RO[Game 3]KM[6.5]DT[2006-12-06]US[GoGoD95]FG[259:]PW[Cho Han-seung]GN[ ]RE[W+1.5]PB[Yi Se-tol]EV[11th Ch'eonweon Final]
;B[qd]
;W[dd]
;B[pq]
;W[oc]
;B[md]
;W[mc]
;B[lc]
;W[ld]
;B[nc]
;W[mb]
;B[me]
;W[nd]
;B[ne]
;W[nb]
;B[pe]
;W[kd]
;B[dp]
;W[qk]
;B[qi]
;W[qo]
;B[cf]
;W[fc]
;B[bd]
;W[cc]
;B[ci]
;W[fq]
;B[dn]
;W[dr]
;B[gq]
;W[gr]
;B[fr]
;W[hq]
;B[gp]
;W[er]
;B[qm]
;W[op]
;B[oq]
;W[np]
;B[mq]
;W[pl]
;B[mp]
;W[on]
;B[qp]
;W[rp]
;B[rq]
;W[pp]
;B[qq]
;W[fp]
;B[ro]
;W[rn]
;B[qn]
;W[so]
;B[po]
;W[ro]
;B[pn]
;W[rm]
;B[oo]
;W[rj]
;B[no]
;W[ri]
;B[fo]
;W[ej]
;B[dh]
;W[cj]
;B[go]
;W[fi]
;B[hr]
;W[fs]
;B[ir]
;W[eg]
;B[bj]
;W[kf]
;B[cq]
;W[cr]
;B[jg]
;W[if]
;B[hi]
;W[ck]
;B[hg]
;W[bk]
;B[bi]
;W[hj]
;B[ij]
;W[hk]
;B[fk]
;W[gi]
;B[ii]
;W[dm]
;B[fm]
;W[cn]
;B[co]
;W[en]
;B[eo]
;W[do]
;B[ek]
;W[bo]
;B[dn]
;W[iq]
;B[jq]
;W[do]
;B[ql]
;W[rl]
;B[dn]
;W[dg]
;B[cg]
;W[do]
;B[gj]
;W[cp]
;B[pk]
;W[of]
;B[oe]
;W[qh]
;B[pj]
;W[oi]
;B[nj]
;W[li]
;B[lj]
;W[kj]
;B[mi]
;W[lh]
;B[ki]
;W[kk]
;B[lk]
;W[mh]
;B[kl]
;W[qf]
;B[pf]
;W[pg]
;B[rf]
;W[rg]
;B[re]
;W[pb]
;B[rb]
;W[rc]
;B[qc]
;W[qb]
;B[sc]
;W[ra]
;B[rd]
;W[sb]
;B[sa]
;W[jk]
;B[ik]
;W[sb]
;B[kg]
;W[lf]
;B[sa]
;W[fn]
;B[gn]
;W[sb]
;B[bp]
;W[co]
;B[sa]
;W[jr]
;B[ip]
;W[sb]
;B[fd]
;W[rc]
;B[gc]
;W[ec]
;B[ee]
;W[sd]
;B[hd]
;W[ge]
;B[gd]
;W[bc]
;B[dj]
;W[he]
;B[ie]
;W[id]
;B[je]
;W[jf]
;B[hf]
;W[ig]
;B[jd]
;W[jc]
;B[ic]
;W[ke]
;B[id]
;W[ih]
;B[hh]
;W[ji]
;B[jl]
;W[dk]
;B[di]
;W[kh]
;B[ni]
;W[nh]
;B[oj]
;W[hs]
;B[hp]
;W[is]
;B[kr]
;W[jb]
;B[ae]
;W[de]
;B[df]
;W[ep]
;B[gb]
;W[ac]
;B[ea]
;W[db]
;B[oh]
;W[og]
;B[ib]
;W[sq]
;B[ja]
;W[rr]
;B[qr]
;W[ka]
;B[ia]
;W[kb]
;B[el]
;W[dl]
;B[da]
;W[ca]
;B[fa]
;W[cd]
;B[ce]
;W[js]
;B[ks]
;W[gs]
;B[qj]
;W[rk]
;B[pi]
;W[em]
;B[jj]
;W[ki]
;B[ed]
;W[eb]
(
;B[ak]
;W[al]
;B[aj]
;W[ad]
;B[be]
;W[fb]
;B[ga]
;W[bb]
;B[ph]
;W[sr]
;TW[aa:ba][ab][am:cm][an:bn][ao][ap:bp][aq:eq][ar:br][as:es][bl:cl][cb][dc][dn][dp][fr][jg:ng][jh][kc:lc][la:qa][lb][le:se][md][mf:nf][nc][ob][od:rd][pc:qc][pf][qg][rb][rf:sf][rh:sh][sa][sc][sg][si:sn]B[rs]TB[af:bg][ah:ch][ai][dg:gg][ef:gf][eh:gi][ej:fj][fe:he][fl:il][gk:hk][gm:pm][ha:hc][hj][hn:on][ho:mo][hq:iq][jp:lp][kq:lq][ll:pl][lr:ps][mj][mk:ok][np:pp][nq][oi]
)
(
;C[*** Correct play.]B[fb]
;W[aj]
;B[ai]
;W[ak]
;B[ad]
;W[bb]
;C[*** But it does not affect the result.]TW[aa:ba][ab][al:cm][an:bn][ao][ap:bp][aq:eq][ar:br][as:es][cb][dc][dn][dp][fr][jg:ng][jh][kc:lc][la:qa][lb][le:se][md][mf:nf][nc][ob][od:rd][pc:qc][pf][qg][rb][rf:sf][rh:sh][sa][sc][sg][si:sn]B[ph]TB[af:bg][ah:ch][be][dg:gg][ef:gf][eh:gi][ej:fj][fe:he][fl:il][ga:ha][gk:hk][gm:pm][hb:hc][hj][hn:on][ho:mo][hq:iq][jp:lp][kq:lq][ll:pl][lr:ps][mj][mk:ok][np:pp][nq][oi]
)
)
Move 231.
Now, to demonstrate that the other move dominates (except in some ko situations), here is the difference game.
(;ST[2]GM[1]CA[ISO8859-1]FF[4]AP[GOWrite:2.2.21]SZ[19]PM[2]C[The difference game is set up, starting from an even position.]PW[ ]FG[259:]GN[ ]PB[ ]AW[ca][db][eb][ec][fc][dd][de][cd][cc][bc][ac][bk][ck][cj][dk][dl][dm][cn][co][bo][ao][dn][ka][kb][kc][kd][ld][md][mc][mb][na][oa][pa][nd][od][oe][of][pf][qf][qe][rd][se][qg][ph][pi][pj][qi][ri][rj]AB[da][ea][fa][gb][gc][gd][fd][ed][ee][df][cf][ce][bd][ae][ef][hd][id][ic][ib][ia][cg][dh][di][ci][bi][bj][dj][qa][ob][pb][oc][nc][pd][pe][qd][qc][rc][sc][so][ro][qo][qn][pn][pm][pl][pk][qk][qj][rk]
;C[*** Then Black plays in the corner on the left. . . .]B[fb]
;W[sk]C[*** And White plays the hane-and-connect on the right.]
;B[sl]
;W[sj]C[*** Now the game is set up. If one player can play and win, while the other cannot, then that player's play dominates the other player's play.]
(
;B[ad]
;W[bb]
;B[ak]
;W[al]
;B[aj]
;W[nb]
;B[sd]
;W[re]
;C[*** Black wins by 1 point. As you can verify, White to play cannot win, so Black's play in the corner is correct, except in some ko situations.]B[rb]
)
(
;W[nb]
;B[ak]
;W[al]
;C[*** Jigo.]B[aj]
)
(
;W[aj]
;B[ai]
;W[ak]
;B[ad]
;W[bb]
;B[nb]
;W[ma]
;B[sd]
;W[re]
;C[*** Jigo.]B[rb]
)
(
;W[ad]
;B[be]
;W[bb]
;B[ak]
;W[al]
;B[aj]
;W[nb]
;B[sd]
;W[re]
;C[*** Jigo.]B[rb]
)
)
The first four plays set up the difference game.