Toroidal go - a big capturing race (Sighris vs Bernhard Herwig)

In this post I would like to go through a game of toroidal go that was played recently (between 2020-12-28 and 2021-06-26) on littlegolem. Like all toroidal go on littlegolem, it was a 11x11 no-handicap correspondence game with komi of 4.5. This game was between two players I’ve played against many times over the last decade or so: Sighris and Bernhard Herwig.

This game was part of an ongoing “ladder” competition in which the players are ranked in a “ladder”. Players lower down the ladder are given games with players higher up the ladder, and if they win then they get to move up the ladder to the position of the player who they beat. I've noticed that the lower-ranked player, the “challenger”, is always given the black stones. Maybe this makes sense - I don't know which side is preferable on 4.5 komi 11x11 toroidal go but it seems that it requires some skilled play by White to avoid letting Black get the upper hand in the opening. Here Sighris had black.

I would describe Bernhard as a very solid player. In my first post about toroidal go (an introduction to toroidal go, 2017) I shared a game from 2015 where I had White against Bernhard and lost. I always find my games against Bernhard very challenging.

Sighris is a player who seems to be improving. Sometimes he gets very good positions in his games but misses one single move that would have lead to the win. This is one such game; and there is another one like that from 2017, where I had White and very nearly lost the game. (I look at that game in depth here.)

Sighris asked me to review this game a few weeks ago and I’m happy to do so as it’s an interesting exercise. And it’s an exciting, fun game where both players seem to be focussed on fighting and trading punches!

From around move 70, I kept an eye on this game while it was underway. At that time, I was also playing another difficult game against Bernhard; maybe I’ll post about that one day.

This was an exciting game. Both players played some nice moves - but also I think there were a few slightly dubious choices; I give some other options to consider in the detailed commentary below.

After some complicated fighting, after white 78 some sort of capturing race was inevitable. I think black 79 was the losing move.

It’s interesting how, despite Black losing the capturing race and White capturing 11 stones, the game is still quite close, because Black gets some compensation. In the end White only won by half a point. (Still, I think White made a few small mistakes in the endgame and probably could have won by a slightly larger margin.)

Prior to the capturing race, there were many moments where the players could have played differently. In particular I think black 55 missed an opportunity. And I’m not sure about white 26. I have provided more comments and variations which you can see if you click on the button below. I hope you enjoy reviewing them. Any comments (on my comments) are welcome!

(;GM[1]FF[4]CA[UTF-8]AP[go-variants-transformer]ST[2]SZ[11]KM[4.5]HA[0]PB[Sighris]PW[Bernhard Herwig]EV[go19.ld.TOROID]SO[https://littlegolem.net/jsp/game/game.jsp?gid=2209090];B[ak];W[be];B[gj];W[gg](;B[jc](;C[This feels a little thin to me.]W[hb](;C[This seems a bit slow to me, but maybe it’s OK.]B[da];LB[hd:A][ec:B]C[I’m not sure about this move, because if Black next plays at ‘A’, it seems a bit hard to handle for White. Maybe with white I would play at ‘A’ or ‘B’ instead here.]W[dh](;B[ec];W[hd];B[ee];C[This feels like a nice, flexible move.]W[jk];B[ia](;C[I’m not convinced by this move. White feels a bit too thin to me.]W[ka](;C[I think this move is a bit inefficient, as white can tenuki (play away) here.]B[fg];MA[hd][gg][jk][be][dh]C[Another nice, flexible move. It reaches out to lots of stones (marked) and makes White’s overall shape seem more coherent.]W[kg];B[ac];W[aa];B[bk];W[ki](;C[This feels like bad shape to me. I believe there must be a better move here. See the variations.]B[kj];W[jj];B[ji];W[hj];B[ii](;C[After this it gets quite complicated - I may not have much to say about the next 25 or so moves.]W[hk];B[kh];W[ai];B[ah];W[bi];B[bh];W[ci];B[cg];W[fh];B[eg];W[ba];B[ck];W[bc];B[eh];W[ei];B[fi];W[dg];B[df];W[ej];B[gk];W[ea];B[db];W[fb];B[ga];W[gb];B[dj];W[di](;LB[fa:A]MA[ia][jc][ac]C[At first I thought this move was strange. It seemed too small ; it doesn’t help the marked stones. But after more thought maybe it’s OK / a good move. It’s solid. ’A’ is now a big problem for White.]B[gh](;W[hi](;C[See the variation, I believe there’s a better move.]B[ek];W[fk];B[dk];W[fj];B[fa];W[gi];B[ha];W[fh];B[hh];W[fi];LB[ih:A][ig:B][eb:C]C[I would have probably considered playing ‘A’, ‘B’ or ‘C’ instead of giving atari here. But maybe this move is OK. It’s hard for me to be sure here.]B[hg];W[gf](;B[ie];W[eb];B[ib];W[fe];B[ef];W[dd];B[dc];W[ed];B[fd];W[fc];B[cd];W[gd](;C[I think this is the losing move. See the variation. In the rest of the game White missed a couple of yose moves so the end result was half a point. Without these mistakes I think White could have won by 2.5 or 3.5 points. Still it’s striking how the result is quite close despite White capturing 11 stones.]B[bd](;W[ce];B[de];W[fd];B[cf];W[cc];B[ad];W[ca];B[he];W[kk];B[ge];W[aj];B[hc](;LB[id:A][jd:B]C[White would get a better result by exchanging ‘A’ for ‘B’ before playing this move.]W[cb];B[id];W[cj];B[ff];W[bj];B[kb];W[ja];B[ab];W[ch];B[hf];W[jb];B[ij];W[ik];MA[ce]C[move 105 White stones captured by Black: 3 Black stones captured by White: 13 result: Black: 28 = 22 territory + 6 prisoners White: 28.5 = 11 territory + 13 prisoners + 4.5 komi Result: W+0.5 --(the content above was generated automatically by GoVariantsTransformer)-- ]B[ic])(;W[id];B[jd];W[cb]))(;C[This also seems to work for White, and is a little better in terms of yose (endgame).]W[cc](;B[bb];W[ce];B[cb];W[cf])(;B[ce];LB[be:A][ce:B]C[This is like the position at move 86 in the game, but in the game White loses an extra stone at B.]W[ca])))(;C[This seems to win the game - see the variations.]B[ce](;W[cc];C[Black wins the semeai (capturing race) by one liberty, as shown by the following moves. So the game is won here for Black.]B[he];W[cb];B[de];W[fd];B[ge];W[ca];B[ff];W[kk];B[id];W[aj];B[hc])(;W[bd];C[This also wins.]B[he])(;W[ic];B[id];W[hc];B[kb];W[he];B[hf];W[ff];LB[ig:A]C[White has made two eyes for one group, but the other group is dead. Black’s shape is a little weak around ‘A’ but I can’t see anything that works for White here.]B[bd])))(;C[Maybe this works for Black.]B[eb]))(;MA[ej][ei][di][dh][dg][ci][bi][ai][ki]C[I think this cut works better. White needs to save the marked stones but I’m not sure it’s possible.]B[fa];W[jh];B[ih];C[What next for Black?]W[jg](;C[This doesn’t seem to work.]B[cf];W[hh];B[ig];C[White has captured the four stones. This is probably hopeless for Black.]W[if])(;C[I think this works.]B[hh];W[cf];B[bf];W[ce];C[It seems to be a win for Black here.]B[af])))(;C[What happens if White cuts here now? (See the following moves.)]W[ha];B[je];W[if];B[jf];W[jg];B[ie];W[hf];B[af];W[bf];B[ag];W[bg];B[jh];W[ig];LB[fa:A]C[This may be good enough for Black. ’A’ is a problem for White.]B[hi]))(;C[Connecting here seems natural - but…]B[ha];C[I think White can resist with this connection. I give one possible continuation.]W[gh];B[ib];W[jh];B[jg];W[ih];B[hh];W[ig];B[hg];W[if];B[gf];W[hi];B[gi];C[It seems to be OK for White.]W[cf]))(;C[Maybe this would be better for White.]W[hi]))(;MA[ki][jk]C[This move is usually a better way, in terms of shape, to cut the keima (knight’s move - marked). ]B[jj];W[kj];B[kk];W[ij];B[ja];C[I wonder if this is OK for Black. It feels like quite a close game.]W[ji];LB[ig:A][je:B][kd:C]C[I count about 11 points for Black. White has 4.5 komi plus 1 captured stone, and so needs to make 7 points more somewhere. A possible next move for White is ‘B’ (and maybe White can get to play ‘C’ with sente later on). After White ‘B’ I don’t see a good way for Black to reduce the potential around ‘A’ so maybe this is not good enough for Black. But I can’t see anything better for Black - see the other variations for black 21.]B[cd])(;MA[hd][hb]C[It seems natural to attack the marked stones, but…]B[ie];W[he];B[if];W[hf];B[ig];C[… it seems White can handle this attack with simple, natural moves.]W[fh];C[If Black cuts…]B[gh];W[hh];B[hg];W[gf];B[gi];W[ef];B[eg];C[… White still seems to be OK]W[df])(;MA[hb][hd]C[Maybe a move like this could prepare an attack on the marked stones.]B[jh];W[kh](;C[This move doesn’t seem to work so well; I give a few possible continuations.]B[ie];W[he];B[if];W[hf];B[fh];W[ig];B[jg];W[jf];B[ih];W[hg];B[je];W[kf];B[ij](;W[gi](;B[hi];W[ik];B[ha];W[hk];B[ga];W[hj];B[gh];W[hh];B[fi];MA[ih][jh][jg][ij]C[Due to a shortage of liberties, Black cannot save the marked stones]W[ii])(;B[ik](;W[hi];B[jj])(;W[jj];B[gh];W[hh];B[ii];W[hi];B[fi];W[hj];B[gk];W[hk];B[ha];W[ga];B[ib];C[White seems to be OK here]W[ic])))(;W[hi];B[jj];W[gi]))(;C[I’m not convinced by this move either.]B[if];W[hf];B[je];W[fh];B[eg];W[ih])))(;MA[hb][hd]C[This feels like a better way to put pressure on the two marked stones.]B[hf]))(;C[Maybe this is good enough for White.]W[je]))(;C[I think would play here. I give one possible continuation.]B[hd];W[eb];B[fc];W[ea];C[I think this is OK for Black]B[ga]))(;MA[hb]C[This seems more active. The marked stone is under attack. I’m not sure how White can handle this - it seems a little unconfortable for White.]B[hd]))(;C[An alternative - maybe this is better. It’s hard to be sure.]W[gc]))(;C[This is probably playable too - there may well be lots of options available.]B[gc]))

Revisions
(2021-07-05): Minor edits/typos in the commentary.
(2021-07-18): Added a link to the next post - an in-depth look at a game I played against Sighris in 2017.