(;FF[4] CA[UTF-8] GM[1] GN[KataGo 7 komi self-play - game 39] PC[https://online-go.com/review/543331] PB[KataGo] PW[KataGo] BR[9p] WR[9p] OT[Error: time control missing] RE[?] SZ[19] KM[7] RU[NZ] ;B[pd] ;W[dd] ;B[cp] ;W[pp] ;B[fq] ;W[qf] (;B[qh]C[In this position, KataGo thinks that pincering is just as good (all comments on this game by Anton Christenson, EGF 3d). ] ;W[nc] ;B[pf] ;W[qc] ;B[pc] ;W[qd] ;B[pe] ;W[rf] ;B[pb] (;W[kc]C[But white wants to resist. ] ;B[rb] ;W[qg] (;B[ph]TR[ri]C[So black is sort of forced to defend like this to be able to hane at S11. ] ;W[rh] ;B[ri] (;W[dp]C[KataGo in this game, before starting the ko, tries to set up a bigger ko threat in preparation. ] ;B[do] ;W[eo] ;B[ep] ;W[dq] (;B[dn]C[So black tries to resist by extending here, allowing white some more room in the corner, but making it so that the ko threat white is going to use would be a little bit more costly. ] ;W[cq] ;B[bp] ;W[rj] ;B[sh] ;W[sg] ;B[rg] ;W[gq] (;B[gp]SQ[dn]TR[gq]C[Even though G3 is working as a ko threat, this is a bad exchange that white has made here. Without the ko, G3 would be quite a bad move to play. This is the compensation that black got for resisting with D6. ] ;W[rh] ;B[jc] ;W[si] ;B[kd] ;W[ld] ;B[le] ;W[jd] ;B[ke] ;W[jb] ;B[ic] ;W[ib] ;B[hc] ;W[hb] ;B[gc] ;W[md] (;B[gb]SQ[gc]SQ[hc]SQ[ic]SQ[jc]TR[dd]C[This is not actually threatening to kill in any way and looks a bit slow to me, but there are some benefits. I think the main purpose of this move is that it's preparing to attack the 4-4 stone and making this chain of black stones a little bit stronger. ] (;W[mf]TR[pg]C[This move is also a bit confusing since the white group is completely alive. It looks as if white is jumping out with a weak group. I think this move has to do with preventing black from completing the influence. We can also see that it threatens the Q13 cut in sente, forcing black to live in the corner. ] (;B[cc]TR[dd]SQ[jd]SQ[ie]C[Black follows up, attacking the 4-4 stone by invading the 3-3, which is quite an unusual way to attack a stone. I see this as removing the base before trying to surround, at least that's my interpretation. It can also have to do with the fact that white still has the option of pulling out the cutting stone at K16, potentially, so there are a lot of factors. ] ;W[pg] ;B[qe] ;W[re] ;B[qb] (;W[fo]C[White first helps the lower-left corner. ] ;B[fp] ;W[er] (;B[df]C[Black gets to continue the attack in the upper left. ] ;W[fr] ;B[hq] ;W[gr] ;B[dh] ;W[gm] (;B[em]TR[go]C[If black comes from this side, then later on, white can push at G5 and make a nice shape. ] (;W[ef]TR[dd]TR[gm]TR[eo]TR[fo]C[First, white attaches up here. There is going to be quite a bit of switching forth here between the upper left area and the lower area. I'm not sure how much of the switching forth is necessary and how much is just KataGo not really caring. White does have to be a little careful because white is sort of creating two weak groups at the same time, so there is definitely some danger here for white to avoid in order not to give black an effective splitting attack. White wants to keep the bottom group quite strong to be able to effectively use the aji in the upper left as well. ] (;B[dg]C[Instead, black tries to give as few forcing moves as possible; just connect solidly here, keep the liberties strong, remove any possibility to play some more attachments here. ] ;W[ie] ;B[ge] ;W[go] ;B[ho] ;W[hn] ;B[io] ;W[in] ;B[jo] ;W[km] ;B[mp] ;W[gf] ;B[hf] (;W[gg]C[KataGo decides to focus on saving these stones directly instead of sacrificing them. ] ;B[he] ;W[cd] ;B[dc] ;W[bc] (;B[be]C[So to prevent white from making eyes, black gets this peep in first. This makes it quite clear that white cannot be making any eyes in this area right now. ] ;W[bd] ;B[bb] ;W[ln] ;B[oq] ;W[ec] ;B[eb] ;W[pq] ;B[fk] ;W[gi] ;B[hj] ;W[fc] ;B[fb] ;W[ab] ;B[ba] ;W[fe] (;B[hl]SQ[hj]SQ[fk]TR[gm]TR[hn]TR[in]TR[eo]TR[fo]TR[go]C[Black tries to use this peep. This is threatening to kill the white stones. It's a very useful move for black to get in sente before continuing to attack the white group because it's solidifying the connection; the knight's move was a bit weak before black played this move. ] ;W[hi] (;B[ij] ;W[ei] ;B[cj] ;W[il] ;B[hg] ;W[de] ;B[fh] (;W[bf]C[White has to back off a little like this. White will be able to make two eyes here. ] (;B[hr]C[This looks like a forcing move to the lower-left corner. ] (;W[no]C[But white actually plays away. ] (;B[cf] ;W[ce] ;B[bg] ;W[ae] ;B[nr] (;W[op]TR[mq]C[So this move is big because it solidifies the corner, but it also sets up some big aji around N3 which we're going to see soon as well. ] ;B[fd] ;W[ed] ;B[fg] ;W[ff] ;B[ag] ;W[af] ;B[gd] ;W[ac] (;B[lj] ;W[bq] ;B[ll] ;W[gj] ;B[gk] ;W[jk] ;B[jj] ;W[kk] ;B[mi] ;W[kj] ;B[ki] ;W[ji] ;B[ii] ;W[jh] (;B[kh] ;W[ih] ;B[hk] ;W[gh] (;B[kg]TR[hb]TR[ib]TR[jb]TR[kc]TR[nc]TR[ld]TR[md]C[Even though right now, this area doesn't look very important, that will not remain so in a couple of moves. We're going to see why L13 is important when that time comes. ] ;W[dj] ;B[ck] ;W[lk] ;B[mk] ;W[ml] ;B[mb] (;W[lb] ;B[nb] (;W[mq]TR[op]C[Even though O18 threatens to kill, white says, "Okay, that's not as important as what I'm going to do on the bottom first!" It was set up by the move at P4 earlier. ] ;B[nq] ;W[lr] (;B[lp]C[So black just extends here instead, allowing white to get the cut in. ] ;W[np] (;B[pr] (;W[mr] (;B[qq]C[So black actually has to continue into the corner. ] ;W[kq] ;B[kp] ;W[jr] ;B[ms] ;W[ls] ;B[or] ;W[js] ;B[qp] ;W[jp] ;B[ka] (;W[og] ;B[nf] ;W[qo] ;B[ro] ;W[rn] (;B[po] ;W[qn] ;B[mm] ;W[nl] ;B[mo] (;W[on]XX[oj]XX[pj]XX[qj]XX[rj]XX[sj]XX[ok]XX[pk]XX[qk]XX[rk]XX[sk]TR[ll]XX[ml]XX[nl]XX[ol]XX[pl]XX[ql]XX[rl]XX[sl]TR[mm]XX[om]XX[pm]XX[qm]XX[rm]XX[sm]XX[pn]XX[qn]XX[rn]XX[sn]SQ[ho]SQ[io]SQ[jo]SQ[mo]SQ[ep]SQ[fp]SQ[gp]SQ[kp]SQ[lp]SQ[mp]SQ[fq]SQ[hq]SQ[hr]C[So white needs to be a bit careful here, backing off with this shape, allowing black to actually save these stones. But white still gets to kill the main part, so the compensation is just that black captures these two white stones. They don't look super big in and of themselves, but it's quite big when you imagine that otherwise this would be a potential white area. ] ;B[om] ;W[mn] ;B[nm] ;W[nn] ;B[nk] (;W[rp] ;B[rq] ;W[so] ;B[rr] ;W[ng] ;B[me] ;W[di] ;B[lm] ;W[pm] ;B[pl] ;W[el] ;B[fm] ;W[kl] ;B[ol] ;W[dl] (;B[fl]TR[dl]C[So black has to connect on this side, and now D8 is threatening to come into the left. ] ;W[kn] (;B[ch] (;W[dk] ;B[cl] ;W[ap] ;B[bo] ;W[ao] ;B[an] ;W[aq] ;B[fi] (;W[fj] ;B[bn] ;W[of] ;B[ne] ;W[hh] ;B[qm] ;W[pn] ;B[rd] ;W[pj] (;B[qk]TR[ph]TR[qh]TR[ri]SQ[rl]C[In the game, black decides to play here, allowing white to capture the stones even though black could have saved them, but in turn black is going to prevent white in the end from connecting up on the right and is even going to make a point there instead. ] ;W[oi] ;B[mg] ;W[dm] ;B[cm] ;W[mh] ;B[lg] ;W[db] ;B[cb] ;W[nj] ;B[mj] ;W[gn] ;B[en] ;W[nh] ;B[rk] ;W[ns] ;B[qj] ;W[qi] ;B[hm] ;W[im] ;B[rm] ;W[os] ;B[qs] ;W[sm] ;B[sl] ;W[pk] ;B[ql] ;W[oe] ;B[od] ;W[sj] ;B[sk] ;W[jg] ;B[jf] ;W[ci] ;B[bi] ;W[ig] ;B[if] ;W[sd] ;B[sc] ;W[se] ;B[ps] ;W[sn] ;B[ms] ;W[sq] ;B[sr] ;W[ns] ;B[sp] ;W[da] ;B[ea] ;W[sq] ;B[ok] ;W[oj] ;B[sp] ;W[aa] ;B[ca] ;W[sq] ;B[jq] ;W[iq] ;B[sp] ;W[da] ;B[db] ;W[sq] ;B[ip] ;W[sp] ;B[jq] ;W[ir] ;B[hs] ;W[kr] ;B[os] ;W[gs] ;B[ms] ;W[lh] ;B[ni] ;W[ns] ;B[hp] ;W[ko] ;B[ms] ;W[rc] ;B[rd] ;W[ns] ;B[oh] ;W[pi] ;B[ms] ;W[sb] ;B[rc]C[KataGo 50 % -- chat -- Maharani: Video review by Anton Christenson, EGF 3d: https://www.youtube.com/watch?v=OV9j4CrEUcc ] )(;B[oi] ;W[ql]TR[ph]TR[qh]TR[oi]C[If black saves these stones, white would get to cut here with quite a nice shape. ] (;B[qk] ;W[rl] ;B[pk] ;W[oj]C[White takes territory along the side while also maintaining a connection. ] ;B[ni] ;W[pi]TR[ni]C[Black would be forced to somehow connect up like this. ] )(;B[ip] ;W[jq] ;B[qk] ;W[rl] ;B[pk] ;W[oj] ;B[ni] ;W[pi] ;B[rk] ;W[sk] ;B[oh] ;W[dm] ;B[cm] ;W[gn] ;B[en] ;W[mg] ;B[qi] ;W[qj] ;B[ns] ;W[jg] ;B[jf] ;W[nj] ;B[mj] ;W[lf] ;B[kf] ;W[lh] ;B[li] ;W[ig] ;B[if] ;W[ci]C[KataGo gives black -2 pp for 225. P11 ] )))(;W[bn] ;B[fj]SQ[di]SQ[ei]SQ[dj]SQ[dk]SQ[dl]SQ[el]TR[bn]C[If white plays at B6, it's slightly better for black to get to kill this. ] ;W[hh] ;B[qm] ;W[cm] ;B[bm] ;W[am] ;B[bl] ;W[pn]C[KataGo gives white -42 pp for 216. B6 ] ))(;W[cm]C[White can't really move in directly since there are cutting points here. ] (;B[dk] ;W[ek] ;B[fj] ;W[fi] ;B[ej]C[Something like this. ] )(;B[bn] ;W[dk]C[KataGo gives white -16 pp for 208. C7 ] )))(;B[ci]C[If black connects here, this makes it so that F11 is actually sente to capture two stones. It won't make a big difference in practice because capturing two stones is not actually big enough. ] (;W[fi]TR[fg]TR[fh] )(;W[eg] ;B[dk] ;W[ch] ;B[cg] ;W[ek] ;B[cl] ;W[eh] ;B[bh] ;W[ap] ;B[hh] ;W[of] ;B[ne] ;W[bn] ;B[co] ;W[ao] ;B[qm] ;W[pn]C[KataGo gives black -9 pp for 207. C11 ] )))(;B[kn]TR[fl]C[At this point, if black cuts here, that's no good if white has the option to cut at F8. ] ;W[jn] ;B[ko] (;W[fl]TR[ii]TR[hj]TR[ij]TR[jj]TR[fk]TR[gk]TR[hk]TR[hl]C[Black is just going to die. ] )(;W[jm] ;B[gn] ;W[fn] ;B[hm] ;W[fl] ;B[gl] ;W[gn] ;B[bn] ;W[hh]C[KataGo gives black -30 pp for 205. L6 ] )))(;W[ol]C[This is actually a ladder that looks funny because it ends in a snapback. ] ;B[pl] (;W[ok] ;B[oj] ;W[pk] ;B[qk] ;W[pj] ;B[qj] ;W[pi] ;B[oi] ;W[qi] ;B[ri]C[Like that. ] )(;W[hh] ;B[ek] ;W[ng] ;B[me]C[KataGo gives white -42 pp for 190. P8 ] )))(;W[nn] ;B[mn] (;W[nm] (;B[lm]TR[kj]TR[jk]TR[kk]TR[lk]TR[il]SQ[ll]TR[gm]TR[km]SQ[mm]TR[hn]TR[in]TR[ln]SQ[mn]TR[eo]TR[fo]TR[go]SQ[ho]SQ[io]SQ[jo]SQ[mo]SQ[ep]SQ[fp]SQ[gp]SQ[kp]SQ[lp]SQ[mp]SQ[fq]SQ[hq]SQ[hr]C[If white is not careful here and just plays like this, this is suddenly a capturing race between the white group and the black group. ] )(;B[jn] ;W[jm] ;B[lm]TR[jn]C[Maybe black should push once before connecting to make sure to stay connected. Black is actually winning this capturing race by a move or so. ] ))(;W[nk] ;B[lm] ;W[kn] ;B[kl] ;W[jl] ;B[jn] ;W[jm] ;B[mj] ;W[ko] ;B[nm] ;W[on] ;B[om] ;W[pm] ;B[pl] ;W[oj]C[KataGo gives white -16 pp for 184. O6 ] )))(;B[qn] ;W[po] (;B[rm] ;W[qr]TR[rn]C[The double hane is a natural shape at this point because black can't really capture like this. Something like this cut would be very annoying. ] )(;B[rp] ;W[ng] ;B[of] ;W[qm] ;B[nl] ;W[mm] ;B[nj] ;W[hh] ;B[mg] ;W[di] ;B[ci] ;W[ch] ;B[bh] ;W[eh] ;B[bn] ;W[el] ;B[fl] ;W[dl] ;B[fm] ;W[eg] ;B[cg] ;W[ok] ;B[nk] ;W[oi] ;B[oj] ;W[pj]C[KataGo gives black -20 pp for 179. R6 ] )))(;W[ng]C[If white tries this one, black could just wedge. ] ;B[og] (;W[of] ;B[oh] ;W[nh] ;B[ne]C[At this point, peep here. ] ;W[me] ;B[ni] ;W[oi] ;B[nf]SQ[hb]SQ[ib]SQ[jb]SQ[lb]SQ[kc]SQ[nc]SQ[ld]SQ[md]SQ[me]SQ[mf]TR[of]SQ[ng]SQ[nh]C[Black can capture the one stone. There's no problems here and white is just completely dead. ] )(;W[oh] ;B[of] ;W[ni] ;B[nj] ;W[oj] ;B[ok] ;W[pj] ;B[mh] ;W[nh] ;B[me] ;W[nl] ;B[qn] ;W[ap] ;B[bn] ;W[hh] ;B[ao] ;W[di] ;B[ci] ;W[ek] ;B[fl] ;W[rm] ;B[rn] ;W[nk] ;B[mj] ;W[qm] ;B[pm] ;W[pn]C[KataGo gives white -11 pp for 174. O13 ] )))(;B[kr] ;W[ns] ;B[or] (;W[qr]TR[kr]C[If black plays anything from this side, white can just capture like this. ] )(;W[kq] ;B[kp] ;W[jr] ;B[qq] ;W[jp]C[KataGo gives black -51 pp for 163. L2 ] )))(;W[qr]C[White can't afford to block in the corner. ] ;B[mr] ;W[lq] ;B[kq] ;W[kr] ;B[jq] (;W[ms]TR[qr] ;B[os]C[Now black is actually able to connect. Black is going to win this capturing race. ] )(;W[nj] ;B[ka] ;W[kp] ;B[ko] ;W[ng] ;B[og] ;W[nh] ;B[ni] ;W[oh] ;B[oj] ;W[nk] ;B[oi] ;W[of] ;B[mj] ;W[nl]C[KataGo gives white -3 pp for 162. R2 ] )))(;B[lq] ;W[mr]TR[lq]SQ[nq]SQ[oq]SQ[nr]C[If black ataris from this side, that reduces black's own liberties. ] ;B[kr] (;W[or]C[This is not working. ] )(;W[ns] ;B[ka] ;W[og] ;B[nf] ;W[ng] ;B[mg]C[KataGo gives black -39 pp for 161. M3 ] ))(;B[mr] ;W[lq] (;B[kq] ;W[kr]TR[mr]C[Atariing from this side is also not quite working. ] (;B[jq] ;W[ms] ;B[pr] ;W[ns] ;B[or] ;W[qr]TR[jq]C[If you extend, white wins this capture race. ] )(;B[jr]C[You can't try anything like this. ] ;W[kp]C[This is just not working. ] ))(;B[jn] ;W[jm] ;B[kq] ;W[kr] ;B[kp] ;W[ms] ;B[pr] ;W[ns] ;B[or] ;W[qr]C[KataGo gives black -44 pp for 161. N2 ] )))(;B[np]C[If black connects here, white gets a perfect connected shape. ] ;W[lp]TR[ho]TR[io]TR[jo]TR[ep]TR[fp]TR[gp]SQ[mp]SQ[np]TR[fq]TR[hq]SQ[nq]SQ[oq]TR[hr]SQ[nr]C[This would be terrible for black. Black just dies on the left, and the other group is quite weak also. ] ;B[lo] ;W[mo] ;B[ko] ;W[mr] ;B[kr] ;W[ns]C[KataGo gives black -45 pp for 159. O4 ] )(;B[lq]C[A little bit of a stronger resistance would be to atari once first and then connect. ] ;W[mr] ;B[np] (;W[lp] ;B[lo] ;W[kq] ;B[kp]C[Even then, we're going to get something along the lines of this. ] ;W[mo]C[We're getting into a ko. ] ;B[lq] ;W[kf]C[White has quite a pleasant ko threat up here. Black can't afford to respond. ] ;B[lp]C[Black doesn't have any big enough ko threats, so black just connects. ] ;W[lf]SQ[ka]XX[hb]XX[ib]XX[jb]XX[lb]XX[kc]XX[nc]TR[kd]XX[ld]XX[md]TR[ke]TR[le]XX[kf]XX[mf]CR[kg]CR[kh]CR[ki]CR[mi]CR[lj]CR[mk]C[White didn't lose a lot on the bottom, but in return got to follow up really nicely up here. It doesn't look huge in and of itself, but the point is that instead of playing some boring gote move to live, white has lived in a really efficient way. It's also potentially threatening to cut the black group off, so M14 is actually really big. This would be good for white. ] )(;W[kq] ;B[lo] ;W[lp] ;B[kp] ;W[mo] ;B[lq] ;W[mj] ;B[lp] ;W[li] ;B[mh] ;W[og] ;B[ka] ;W[nf] ;B[oh] ;W[pj] ;B[hh] ;W[di] ;B[ci] ;W[ap] ;B[kb] ;W[lc] ;B[la] ;W[ps] ;B[os] ;W[pr] ;B[bo] ;W[ao] ;B[an] ;W[aq] ;B[nj] ;W[nk] ;B[bn] ;W[sc] ;B[oj] ;W[ok] ;B[qi] ;W[qj] ;B[hs] ;W[jn] ;B[rc] ;W[jq] ;B[jr] ;W[js] ;B[is] ;W[kr]C[KataGo gives black -12 pp for 159. M3 ] )))(;W[ka]XX[hb]XX[ib]XX[jb]XX[lb]SQ[nb]XX[kc]XX[nc]TR[kd]XX[ld]XX[md]TR[ke]TR[le]TR[kg]TR[kh]TR[ki]C[Because black is so strong on the outside, O18 threatens to kill the white group. White can just live. ] ;B[nl] ;W[mm] ;B[nk] ;W[nq] ;B[mq] ;W[or] ;B[ql] ;W[mr] ;B[lr] ;W[ns] ;B[kp] ;W[hh] ;B[qo] ;W[di] ;B[ci]C[KataGo gives white -27 pp for 156. L19 ] )(;W[me] ;B[kf]TR[ka]C[If we pretend that white had played N15 in sente, right now white wouldn't be forced to live in gote. ] ))(;W[nb] ;B[kb] (;W[lc] ;B[lb]SQ[hb]SQ[ib]SQ[jb]TR[nb]C[White can't block from this side because the three stones die. ] )(;W[ng] ;B[og] ;W[of] ;B[oh] ;W[nh] ;B[ne] ;W[me] ;B[nf] ;W[ni] ;B[mg]C[KataGo gives white -59 pp for 154. O18 ] )))(;B[hh]TR[ih]TR[jh]SQ[kh]TR[ji]SQ[ki]SQ[mi]SQ[lj]C[One question I had at this point was, why wouldn't you simply kill these three stones? It's actually not possible for white to save them, so this seems like a better way to save the black stones. ] ;W[kg] ;B[jg] (;W[kf]C[There's a little bit of aji here, which is not actually working to kill anything. ] ;B[jf] ;W[je] ;B[id] ;W[me] ;B[if]TR[kd]TR[ke]TR[le]SQ[me]C[White doesn't even get to kill these stones, but getting the extra connection at N15 is going to turn out to be quite big in a few moves. ] )(;W[dj] ;B[nm] ;W[nl] ;B[ml] ;W[nj] ;B[mj] ;W[mo] ;B[lp] ;W[ck] ;B[bj] ;W[ek] ;B[di] ;W[bn] ;B[mb] ;W[lb] ;B[nb] ;W[el] ;B[cl] ;W[bl]C[KataGo gives black -1 pp for 147. H12 ] )))(;B[ih]C[It's annoying for black because, if you come out like this, white gets a pleasant atari. ] ;W[kh] ;B[li] ;W[kf]TR[ph]TR[qh]TR[ki]TR[li]TR[mi]TR[ri]TR[lj]TR[ll]C[With a white shape like this, now suddenly black is cut off in the center and is really going to struggle to live with the right side. ] ;B[ok] ;W[oh] ;B[nm] ;W[mo] ;B[oi] ;W[nh] ;B[pm] ;W[ni] ;B[nj] ;W[lk]C[KataGo gives black -23 pp for 143. J12 ] ))(;B[br] ;W[bq] ;B[aq] (;W[cr] ;B[ds] ;W[ar] ;B[as] ;W[cs] ;B[ap] ;W[bs] ;B[ar] ;W[co] ;B[bo] ;W[cn] ;B[bn] ;W[cm] ;B[bm] ;W[dm] ;B[en] ;W[el]TR[eo]TR[fo]TR[go]C[In this variation, white has to be prepared to give up the three stones. ] ;B[dl] ;W[cl] ;B[fl] ;W[dk] ;B[fm] ;W[bl] ;B[gn]TR[eo]TR[fo]TR[go]SQ[ho]SQ[io]SQ[jo]SQ[ep]SQ[fp]SQ[gp]SQ[mp]SQ[fq]SQ[hq]SQ[oq]SQ[hr]SQ[nr]C[Black can capture these three stones in a snapback. They seem really small right now, but we're going to see in a few moves that there's going to be a big trade here where white suddenly kills this group. ] )(;W[co] ;B[bo] ;W[ar] ;B[as] ;W[cn] ;B[cm] ;W[cr] ;B[lj] ;W[gj] ;B[jl] ;W[gk] ;B[im] ;W[jn] ;B[gl] ;W[gh] ;B[ko]C[KataGo gives black -4 pp for 129. B2 ] )))(;W[bq]C[What would happen if white plays away? It's not game-losing, only a slight loss for white it seems to me. ] ;B[pr]C[Black could start with this hane. ] ;W[qr]C[White will have to block here, but is not going to be able to keep this stone alive. ] ;B[mo] ;W[mn] ;B[oo] ;W[op] ;B[np] ;W[nn] ;B[qq]C[With this sequence, black can cut. ] ;W[ps] ;B[or] ;W[qp] ;B[rq] (;W[rr]C[At this point, white can't play from the corner. ] ;B[rp]C[Black is going to come out like this. ] )(;W[rp]TR[qr]TR[ps]C[White has to give up these stones to play some move in the center. ] ;B[rr] (;W[li]TR[qq]C[This is close to even still, but this demonstrates the danger of the cutting aji: Black can steal away the corner if white doesn't protect. ] )(;W[mj] ;B[nh] ;W[og] ;B[lh] ;W[gh] ;B[fg] ;W[ff] ;B[kg] ;W[ek]C[KataGo gives white -5 pp for 120. B3 ] ))))(;B[br]C[This raises the question, what would happen if black just went for the kill at this point? ] ;W[bq] ;B[aq] (;W[cr] ;B[ds]C[We could throw in like this and it looks like white doesn't have two eyes. ] ;W[ar] ;B[as] ;W[cs] ;B[ap] ;W[bs] ;B[ar] ;W[co]C[But there's going to be some problems here when white gets this cut. ] ;B[bo] ;W[cn] ;B[bn] ;W[cm] ;B[bm] ;W[dm] ;B[en] ;W[el] ;B[dl]TR[em]TR[dn]TR[en]TR[do]C[At this point, if black wants to save these four stones, black has to exchange this atari and come out in that way. ] ;W[cl] ;B[fl] ;W[dk] ;B[fm] ;W[bl]TR[bm]TR[bn]TR[bo]TR[ap]TR[bp]TR[cp]TR[aq]TR[ar]TR[br]TR[as]C[Then white would be able to kill these stones and this is a disaster. ] ;B[gn]SQ[bm]SQ[bn]SQ[bo]TR[eo]TR[fo]TR[go]SQ[ap]SQ[bp]SQ[cp]SQ[aq]SQ[ar]SQ[br]SQ[as]C[Black can kill these stones, but definitely not big enough compared to what black lost on the left. ] )(;W[ar] ;B[cf] ;W[ce] ;B[bg] ;W[ae] ;B[as] ;W[co] ;B[bo] ;W[cn] ;B[cm] ;W[cr] ;B[pr] ;W[op] ;B[or] ;W[qr] ;B[np] ;W[mo] ;B[lp]C[KataGo gives black -5 pp for 115. B2 ] )))(;W[bq]C[It would be quite natural for white to just protect the corner like this. ] ;B[fg] ;W[bg] ;B[bh] ;W[ch] ;B[ci] ;W[cg] ;B[op] ;W[oo] ;B[no] ;W[nn] ;B[on] ;W[po] ;B[mn] ;W[nm] ;B[mm] ;W[lo] ;B[mo] ;W[lp] ;B[lq] ;W[kq] ;B[lr]C[KataGo gives white -9 pp for 114. B3 ] ))(;B[cf] ;W[ce] ;B[bg] ;W[ae]TR[ad]TR[ee]C[We could get something like this where white has one eye for sure and has one potential eye at A16 and one potential eye at E15, but they won't play it out just yet. ] ;B[hr] ;W[no] ;B[nr] ;W[op] ;B[fg] ;W[bq] ;B[ff] ;W[fd] ;B[ee] ;W[ac] ;B[ag] ;W[af] ;B[kj] ;W[fl] ;B[el] ;W[gk] ;B[gj] ;W[lj]C[KataGo gives black -2 pp for 113. C14 ] ))(;W[eh] ;B[eg] (;W[fg] ;B[gh]C[This is not working for white. ] )(;W[bf] ;B[gh] ;W[bg] ;B[bh] ;W[bi] ;B[ch] ;W[ae] ;B[hr] ;W[no]C[KataGo gives white -36 pp for 112. E12 ] )))(;B[jn]C[What would happen if black just cuts right now? It's not a terrible move, it's only slightly worse than what happened in the game. ] ;W[jm] (;B[im]TR[gm]TR[hn]TR[in]TR[eo]TR[fo]TR[go]C[Basically, KataGo thinks it's not quite worth it to just get these stones because white is going to get some very nice compensation by using this aji. ] ;W[fj]TR[be]TR[df]TR[dg]TR[dh]SQ[dj]TR[em]TR[dn]TR[do]C[To start with, white can play here. It's very important for black to stay connected on the left here. If white could just jump into D10, for instance, that would really put a lot of pressure in there, remove all the black territory. ] ;B[ek]TR[dh]C[So black is going to try to stay connected. ] ;W[gk]C[Then white can come in like this. ] ;B[gl]TR[gm]TR[hn]TR[in]TR[eo]TR[fo]TR[go]C[Black tries to keep these stones dead. ] ;W[il] ;B[hm]TR[hk]TR[fl]C[Now white has two ataris here. White is not going to choose yet. In the end, white is going to want the H9 atari, but first white is going to push and wedge. ] ;W[ej] ;B[dj] ;W[di]TR[fl]C[Now it's still good to have the other atari in reserve because that makes it so black can't atari from below here. ] (;B[ci]C[This would open up (not sure what's the best order) some double atari here. ] ;W[dk] ;B[ei] ;W[fl]C[This is really a terrible result for black. ] )(;B[cj]C[So at this point, black would have to back down like this. ] ;W[ci] ;B[bi]C[Black is actually able to connect up. ] ;W[bh] ;B[ch] ;W[ei] ;B[bj]SQ[bi]TR[ci]TR[di]C[The sequence could be something like this. Black is able to connect up, but white also gets to save these two stones and push black down a bit. ] ;W[hk] ;B[fl] ;W[ik]XX[bc]XX[bd]XX[cd]XX[dd]XX[fe]XX[ef]XX[gf]XX[gg]CR[pg]CR[qg]CR[rh]XX[ci]XX[di]XX[ei]XX[gi]XX[hi]CR[si]XX[ej]XX[fj]CR[rj]SQ[bk]SQ[ck]SQ[dk]XX[gk]XX[hk]SQ[bl]SQ[cl]SQ[dl]XX[il]SQ[bm]SQ[cm]SQ[dm]TR[gm]XX[jm]XX[km]SQ[bn]SQ[cn]TR[hn]TR[in]XX[ln]SQ[bo]SQ[co]TR[eo]TR[fo]TR[go]C[Then, in the end, white comes back and gets to protect like this. The end result is that black did successfully kill these stones and even kept the territory here, but white got super strong in the center. What was a weak group before is now definitely alive. That would really connect up nicely with the influence white has on the right side of the board. ] ;B[pn]TR[bc]TR[bd]TR[cd]TR[dd]TR[fe]TR[ef]TR[gf]TR[gg]TR[ci]TR[di]TR[ei]TR[gi]TR[hi]TR[ej]TR[fj]TR[gk]TR[hk]TR[ik]TR[il]TR[jm]TR[km]TR[ln]C[So next up, it's actually black who will have to (sort of) invade in this area, and I think there is potential for black being the one who is going to be attacked for the next few moves. This explains why KataGo thinks in this position, white is slightly better with all this nice influence. ] ))(;B[kb] ;W[lc] ;B[im] ;W[fj] ;B[ek] ;W[gk] ;B[gl] ;W[il] ;B[hm] ;W[ej] ;B[de] ;W[ee] ;B[dj] ;W[di] ;B[cj] ;W[ci] ;B[bi] ;W[dk] ;B[ei] ;W[fl] ;B[gj] ;W[el]C[KataGo gives black -8 pp for 105. K6 ] )))(;B[de]C[Black could remove the eyes here locally by playing here, for instance. There would be no eyes locally, but this would not necessarily be sente at this point so black would prefer to attack it on a larger scale; attack the whole group rather than just cutting off the tail. ] ;W[ei] ;B[dj] ;W[ih] ;B[op] ;W[oo] ;B[no]C[KataGo gives black -12 pp for 103. D15 ] ))(;B[bb]C[If black were to just hane here, this would allow a white move like B15 which is sort of a flexible shape. ] ;W[be]C[If you decide attacking this shape, it's very hard to keep this from making eyes. ] (;B[bg]C[If black plays from this side, white gets a pleasant hane. ] ;W[ab] )(;B[ac]C[From this side, white can block with a ko sort of shape. ] ;W[ad] ;B[ab]C[Eventually black will be forced to connect. ] ;W[bg] )(;B[hr] ;W[bq] ;B[fk] ;W[bg] ;B[ci] ;W[ab] ;B[cb] ;W[ec] ;B[eb] ;W[cf] ;B[qq] ;W[pq] ;B[qp] ;W[po] ;B[rn] ;W[qn] ;B[nq] ;W[ro] ;B[pr] ;W[or] ;B[qr] ;W[oq] ;B[qo] ;W[rm] ;B[pn] ;W[qm] ;B[nr] ;W[on] ;B[os] ;W[lo] ;B[pm] ;W[om] ;B[pl] ;W[oo] ;B[mb] ;W[lb] ;B[og] ;W[oh] ;B[nh] ;W[oi] ;B[ni]C[KataGo gives black -2 pp for 87. B18 ] )))(;W[he]C[Definitely, my first instinct would be to cut here, just based on the shape. This is also KataGo's first instinct, but after thinking about it for a few thousand playouts, it decides that it's better to just extend. Cutting like this would also be playable, it's only a little bit worse. ] ;B[ff] ;W[gg] ;B[fe]C[White would give up this big corner completely and just get compensation in terms of a stronger position on the outside, which looks hard for me to play. ] ;W[fg] ;B[eg] ;W[ln] ;B[hr] ;W[lq] ;B[lo] ;W[mq] ;B[mn] ;W[mm] ;B[no] ;W[nn] ;B[kn] ;W[mo] ;B[nq] ;W[ee] ;B[fc] ;W[nr] ;B[mn]C[KataGo gives white -3 pp for 82. H15 ] ))(;B[eg]C[It would be quite natural to try to close white in with this shape, but this will allow some response like C14. ] (;W[cf] ;B[ff] ;W[cd] ;B[dc] ;W[bc] ;B[bb] ;W[be]C[This shape looks like it's going to be quite flexible for white, and I think white would be able to handle this somehow, at least get some ko. ] )(;W[go] ;B[ho] ;W[hn] ;B[io] ;W[in] ;B[jo] ;W[km] ;B[hr] ;W[cf] ;B[br] ;W[bq] ;B[aq] ;W[ar] ;B[as] ;W[cr] ;B[dc] ;W[mq] ;B[lo] ;W[np] ;B[mn] ;W[de] ;B[dg] ;W[bh] ;B[bj] ;W[bd]C[KataGo gives black -0.7 pp for 69. E13 ] )))(;W[go] ;B[ho] ;W[hn] ;B[io] ;W[in] ;B[jo] ;W[jn] ;B[ko] ;W[ef] ;B[eg] ;W[cf] ;B[ff] ;W[cd] ;B[dc] ;W[bc] ;B[bb] ;W[be] ;B[kn] ;W[km] ;B[lm] ;W[kl] ;B[ac] ;W[bh] ;B[bi] ;W[ci] ;B[bg] ;W[bj] ;B[cg] ;W[cm] ;B[bn] ;W[bm] ;B[ek] ;W[ll] ;B[ck] ;W[bk] ;B[cl] ;W[bl] ;B[cj] ;W[di]C[KataGo gives white -1 pp for 68. G5 ] ))(;B[go]C[If black pushes here, white makes a very nice shape and presses black on the left. ] ;W[em] ;B[dm] ;W[el] ;B[dl] ;W[ek] ;B[gn] ;W[fm] ;B[cj] ;W[im] ;B[jn] ;W[in] ;B[jp] ;W[jo]C[KataGo gives black -9 pp for 67. G5 ] ))(;B[fr]TR[gq]C[White made a questionable exchange earlier, but is still able to live quite easily in this corner. Even if black were to block here, this corner is not 100 % alive, but close enough for practical purposes. ] ;W[bq] ;B[df] ;W[bn] ;B[cl] ;W[cd] ;B[kb] ;W[lc] ;B[dc] ;W[bc] ;B[bb] ;W[cf] ;B[cg] ;W[dg] ;B[bf] ;W[ce] ;B[ch] ;W[eg] ;B[ei] ;W[ec] ;B[eb] ;W[fc] ;B[fb] ;W[be] ;B[co] ;W[nq] ;B[mp] ;W[np] ;B[mn] ;W[gm] ;B[im] ;W[go] ;B[hp] ;W[in] ;B[hn] ;W[ho] ;B[io] ;W[jn]C[KataGo gives black -0.3 pp for 61. F2 ] ))(;W[rc]C[Black is completely alive locally. Even if white were to play here, black can always come out and threaten to live. ] (;B[sc] ;W[rd] ;B[nb] ;W[mb] ;B[na] ;W[sb] ;B[sa] ;W[oc] ;B[ob]C[Something like this. ] )(;B[dc] ;W[ch] ;B[og] ;W[me] ;B[sc] ;W[ck] ;B[hq] ;W[bq] ;B[er]C[KataGo gives white -7 pp for 58. S17 ] ))(;W[ch]TR[dd]C[If I were white in this position, I would probably want to play on the left. The 4-4 stone is starting to look quite weak. ] ;B[cd] ;W[ck] ;B[cg] ;W[dg] ;B[cf] ;W[dh] ;B[qq] ;W[qp] ;B[pq] ;W[op] ;B[oq] ;W[np] ;B[mr]C[KataGo gives white -4 pp for 58. C12 ] ))(;B[mb]TR[gb]C[G18 also sets up the possibility for this move later. ] (;W[nb]C[If white blocks like this, we can see that G18 plays an important role here. ] ;B[kb] ;W[lc] ;B[lb]TR[gb] )(;W[lb] ;B[nb] ;W[me] ;B[df] ;W[jf] ;B[cc] ;W[dc] ;B[cd] ;W[de] ;B[ce] ;W[ef] ;B[je] ;W[ie] ;B[id] ;W[kf] ;B[ee] ;W[qb] ;B[qe] ;W[re] ;B[pg] ;W[eb] ;B[ed] ;W[cb] ;B[bb] ;W[cf] ;B[dg] ;W[be] ;B[ca] ;W[db]C[KataGo gives black -0.4 pp for 53. N18 ] ))(;B[cf]C[If you try to attack from this side, white can attach on the outside and so on. ] (;W[df] )(;W[cc]C[After playing some moves on the outside, white even has the option of coming back and taking the 3-3 point, which is making quite a lot of eye-shape in the corner. ] )(;W[me] ;B[ee] ;W[be] ;B[bf] ;W[ed] ;B[mb] ;W[lb] ;B[qe] ;W[re] ;B[nb] ;W[qb] ;B[pg] ;W[jf] ;B[fe] ;W[eb] ;B[hq] ;W[bq] ;B[er] ;W[bn] ;B[co]C[KataGo gives black -0.3 pp for 53. C14 ] )))(;W[cf]C[If white just plays elsewhere, white can easily live locally. ] (;B[mb] ;W[lb] ;B[nb] (;W[ka] )(;W[me] ;B[mf] ;W[nf] ;B[ng] ;W[ka] ;B[lg] ;W[je] ;B[gf] ;W[kg]C[KataGo gives white -4.5 pp for 52. C14 ] ))(;B[nf]C[It's quite a nice point. ] )))(;B[cf] ;W[nf] ;B[qe] ;W[re] ;B[ef] ;W[qb] ;B[qa] ;W[rc] ;B[mb] ;W[lb] ;B[nb] ;W[me] ;B[pg] ;W[ie] ;B[kg]C[KataGo gives black -1 pp for 51. C14 ] ))(;B[sf]TR[gq] ;W[fp]C[If black were to finish right now, this would be a very big capture for white. ] ;B[cc] ;W[dc] ;B[cd] ;W[de] ;B[bf] ;W[cl] ;B[cg] ;W[bn] ;B[ic] ;W[ke] ;B[ie] ;W[el] ;B[fl] ;W[ek]C[KataGo gives black -1.5 pp for 35. T14 ] ))(;B[cq]TR[dp]TR[dq]C[If we just look at this corner in isolation, the natural next move for black would be to block like this and there's not much white can do with these stones. ] (;W[dn]C[White will just be able to get this forcing move. ] ;B[co]TR[dn]C[It looks like a local failure for white, but actually, this is a very pleasant ko threat to get. ] )(;W[rj] ;B[sh] ;W[sg] ;B[rg] ;W[dn] ;B[co]SQ[dn]TR[cq]C[I think the reason black doesn't play at C3 in this case is that it would be perfect to be able to use the D6 ko threat and win the ko in this way. ] ;W[rh] ;B[jc] ;W[si] ;B[kd]C[Something like this. ] ;W[jb] ;B[jd] ;W[kb] ;B[hc] ;W[ld] ;B[md] ;W[le] ;B[mc] ;W[me] ;B[mb] ;W[fc] ;B[jf] ;W[fo] ;B[hq] ;W[ib] ;B[gc]C[KataGo gives black -7 pp for 27. C3 ] )))(;W[sg]C[At looks at first glance like white wouldn't be able to live locally, but actually, white could probably live locally with this, but it's a bit slow. ] (;B[se]TR[pg]TR[rj]C[Black can't really go in for the kill at this point with the aji of the cut and the clamp and so on. ] )(;B[pg] ;W[dp] ;B[do] ;W[cq] ;B[dq] ;W[ep] ;B[eq] ;W[co] ;B[bp] ;W[dn] ;B[eo] ;W[fp] ;B[gq] ;W[fo] ;B[en] ;W[cn] ;B[bq] ;W[dl] ;B[fn] ;W[hp] ;B[hn] ;W[ho]C[KataGo gives white -16 pp for 22. T13 ] ))(;W[rj]C[White would really like, at this point, to be able to play this clamp, but the problem is that when white clamps here, it's going to start a ko. ] ;B[sh]C[Black will atari. ] ;W[sg]C[White has to block like this. ] ;B[rg]C[Right now, white doesn't really have a big enough ko threat. ] (;W[dp]C[This is not big enough. ] ;B[sf]C[Black will just ignore, and this result is a bit good for black, I think. ] )(;W[pg]C[The best white can do here is push out like this. ] ;B[sf] ;W[og]C[I think this actually seemed to be fine for both, also, but I find it slightly uninteresting for white. ] (;B[md]C[Right now, this black group can probably go out somehow in this area. ] ;W[nf] ;B[mc] ;W[pj] ;B[oi] ;W[me] ;B[nd] ;W[ke] ;B[qn] ;W[pn] ;B[pm] ;W[on] ;B[ro] ;W[om] ;B[pl] ;W[oj] ;B[ni] ;W[nj] ;B[mi] ;W[rq] ;B[rk]C[KataGo gives white -3 pp for 22. S10 ] )(;B[se]TR[pg]C[Later on, black also has the option of still connecting up in the corner. I think this sort of sequence has been played in pro games before. This idea of playing the local ko threat at Q13 is not anything new. ] ))))(;B[pg]C[If black blocks like this, then it's very easy for the white group to settle. ] ;W[rh] ;B[qi] ;W[ri] ;B[qj] ;W[nq] ;B[rj] ;W[rc] ;B[qb] ;W[sb] ;B[ic] ;W[ke] ;B[fc] ;W[ec] ;B[fd] ;W[cf] ;B[de] ;W[ce] ;B[cc] ;W[ed]C[KataGo gives black -5 pp for 19. Q13 ] ))(;W[qb]C[If white just responds for the corner, which is completely fine, then black will get some sort of pincer. ] ;B[kd]SQ[pb]SQ[pc]SQ[pd]SQ[pe]SQ[pf]TR[pg]C[We have quite a peaceful result. There is some aji for the Q13 cut later on, but with the Q18 forcing move, black has strengthened his group a bit. This result is playable for both. ] ;W[pg] ;B[md] ;W[nf] ;B[nd] ;W[dp] ;B[dq] ;W[qm] ;B[fc] ;W[co] ;B[bp] ;W[cf] ;B[nq] ;W[oi] ;B[pl]C[KataGo gives white -1 pp for 16. R18 ] ))(;B[nc]C[Nowadays, we most commonly just back off (all comments on this game by Anton Christenson, EGF 3d). ] ;W[dp] ;B[dq] ;W[co] ;B[ep] ;W[do] ;B[bp] ;W[eo] ;B[fo] ;W[fn] ;B[bo] ;W[go] ;B[fp] ;W[gm] ;B[dm] ;W[qd] ;B[qc] ;W[rc] ;B[qe] ;W[rd] ;B[pf] ;W[re] ;B[pe] ;W[qg] ;B[cf] ;W[fc] ;B[cd] ;W[cc] ;B[bc] ;W[ce] ;B[bd]C[KataGo gives black -0.6 pp for 7. O17 ] ))