(;
PW[Albert Yen]
WR[7d]
PB[Jaesung Lee]
BR[7d]
EV[WAGC]
RO[8]
DT[2019-06-11]
PC[Matsue, Shimane, Japan]
RE[B+Resign]
RU[Japanese]
ST[2]
WT[USA]
BT[South Korea]
TM[3600.0]
OT[3x30 byo-yomi]
C[World Amateur Go Championship
White: Albert Yen, 7D
Black: Jaesung Lee, 7D
June 5, 2019, in Matsue, Shimane Prefecture, Japan
Comments by Albert Yen, 7D
Game editors:  Kiren Polara, Myron Souris

Albert Yen's commentary here is from his 8th round loss against South Korea's Jaesung Lee.  Albert's analysis covers the complicated middle game fighting, when one misread turns an even game into an almost immediate loss.  For the game moves, Albert also includes LeelaZero's (AI) winrates.

This work is licensed under the Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International License.  To view a copy of this license, visit http://creativecommons.org/licenses/by-nc-nd/4.0/ or send a letter to Creative Commons, PO Box 1866, Mountain View, CA 94042, USA.];
B[cq]
C[45.9% (-0.6%)
1.0k playouts

Note:  LeelaZero's winrate percentage above is the winning estimation for the player who just moved.  The parenthesized percentage is how much the winning estimation increased (or decreased) as a result of the given move.  The playout count (in this case 1000) indicates the number of Monte Carlo runs in the game tree search - very roughly speaking, the more playouts the better the estimation.

Be warned that the winrates in this game may not be completely accurate, because WAGC uses Japanese rules, which has a 6.5 point komi rather than LeelaZero's 7.5 point komi.  In a normal game this would barely make a difference, but because the margin of lead in this game is very small throughout one point can make a big impact.  In other words, Black's position is always better than what the winrate indicates.];
W[pd]
C[54.1% (0.0%)
1.0k playouts];
B[dc]
C[46.4% (0.4%)
1.0k playouts];
W[pq]
C[54.3% (0.7%)
1.0k playouts];
B[cf]
C[45.8% (0.1%)
1.0k playouts];
W[qn]
C[54.2% (-0.0%)
1.0k playouts];
B[nc]
C[45.6% (-0.1%)
1.0k playouts];
W[qf]
C[54.1% (-0.2%)
1.0k playouts];
B[pc]
C[46.2% (0.3%)
1.0k playouts

This is a very common AI joseki nowadays.];
W[qc]
C[53.9% (0.0%)
1.1k playouts];
B[qb]
C[46.1% (0.0%)
1.2k playouts];
W[oc]
C[53.9% (-0.0%)
1.2k playouts];
B[pb]
C[46.2% (0.0%)
1.3k playouts];
W[nd]
C[54.1% (0.3%)
1.0k playouts];
B[ob]
C[45.9% (0.0%)
1.1k playouts];
W[od]
C[54.1% (0.0%)
1.1k playouts];
B[mc]
C[45.9% (0.0%)
1.1k playouts]
(;
W[dp]
LB[de:B][jp:A]
C[54.0% (-0.0%)
1.0k playouts

Playing at A or B are also big points.  I chose a rather traditional move here because I am not very familiar with the followups of the first joseki.];
B[cp]
C[46.0% (-0.0%)
1.0k playouts];
W[dn]
C[54.3% (0.2%)
1.0k playouts];
B[ep]
C[45.5% (-0.2%)
1.0k playouts];
W[eo]
LB[md:A]
C[50.8% (-3.6%)
1.0k playouts

Leela doesn't like me spending so many moves in the bottom left (A is Leela's first choice).];
B[dq]
C[49.5% (0.3%)
1.0k playouts];
W[fp]
C[46.6% (-3.9%)
1.0k playouts];
B[do]
C[53.4% (-0.0%)
1.1k playouts];
W[fo]
C[48.4% (1.8%)
1.0k playouts];
B[md]
LB[cn:A]
C[42.9% (-8.7%)
1.0k playouts

Black should've made a few exchanges at A before tenuki.];
W[rc]
LB[cn:A]
C[45.1% (-12.0%)
1.0k playouts

I should've taken this chance to play the descent at A.  The game move is slow.];
B[pg]
C[51.6% (-3.3%)
1.0k playouts];
W[rh]
C[47.5% (-1.0%)
1.0k playouts];
B[cn]
C[53.1% (0.6%)
1.0k playouts

Black is happy to be able to come back to this move.];
W[dm]
C[46.9% (-0.0%)
1.1k playouts];
B[cm]
C[53.3% (0.2%)
1.1k playouts];
W[dl]
C[46.2% (-0.6%)
1.0k playouts];
B[fq]
LB[hp:A][kp:B]
C[45.0% (-8.8%)
1.0k playouts

This move is a mistake.  Black should play at A or B to split White's side.];
W[gq]
C[55.2% (0.2%)
1.0k playouts]
(;
B[gp]
LB[fr:A]
C[41.8% (-3.0%)
1.0k playouts

I was very surprised to see this move.  I thought Black would definitely descend at A.];
W[fr]
C[58.5% (0.3%)
1.0k playouts];
B[eq]
C[41.6% (0.1%)
1.1k playouts];
W[hq]
C[58.1% (-0.3%)
1.0k playouts]
(;
B[gn]
LB[hp:A]
C[41.7% (-0.2%)
1.0k playouts

This is a tesuji but in this case is actually the same as playing at A.];
W[fm]
LB[go:A]
C[57.8% (-0.5%)
1.0k playouts

Pushing out at A is also possible, but I chose the gentler move.];
B[hp]
C[43.7% (1.6%)
1.0k playouts];
W[ip]
C[57.3% (1.1%)
1.0k playouts];
B[hn]
C[44.0% (1.3%)
1.0k playouts];
W[jq]
C[56.9% (0.8%)
1.0k playouts];
B[gl]
C[43.2% (0.1%)
1.0k playouts]
(;
W[fl]
LB[di:A]
C[48.9% (-7.9%)
1.0k playouts

In my mind I really thought this push is necessary before playing at A because I didn't want Black to get this point and threaten White's eye shape.  However, it's an inside-outside exchange so White takes a loss here.];
B[gk]
C[51.3% (0.2%)
1.0k playouts];
W[di]
C[48.6% (-0.1%)
1.0k playouts];
B[kn]
C[51.9% (0.5%)
1.0k playouts];
W[il]
LB[gm:B][in:A]
C[49.4% (1.3%)
1.0k playouts

I am proud to sense this move soon after Lee played the two-space jump.  I threaten to separate Black at A and B.  While White wouldn't start the fight right away this cutting point will be a bit annoying for Black to handle later.];
B[ir]
C[50.1% (-0.5%)
1.0k playouts];
W[iq]
C[50.2% (0.3%)
1.0k playouts];
B[jm]
C[50.9% (1.1%)
1.0k playouts];
W[gi]
LB[dg:A][fj:B]
C[47.6% (-1.5%)
1.0k playouts

A simple jump at A is better because there's bad aji at B.  White's group is not fully connected yet.];
B[hi]
C[52.6% (0.2%)
1.0k playouts];
W[hh]
C[48.1% (0.7%)
1.0k playouts];
B[hj]
C[50.0% (-1.8%)
1.0k playouts];
W[ih]
LB[gh:A]
C[44.3% (-5.7%)
1.0k playouts

I had some misreading involving the follow-up to the cut at A.  This move ended up costing me the game.];
B[gh]
C[56.3% (0.5%)
1.0k playouts];
W[fi]
C[44.0% (0.3%)
1.0k playouts];
B[gg]
C[56.1% (0.2%)
1.0k playouts]
(;
W[df]
LB[dg:B][ih:A]
C[33.9% (-10.0%)
1.0k playouts

I thought this move works, so I played at A.  However, I had some reading errors here.  I was essentially finished with one blow.  If I jump at B here instead, the game is still playable.];
B[dg]
C[67.2% (1.1%)
1.0k playouts];
W[eg]
C[31.2% (-1.6%)
1.0k playouts];
B[ef]
C[68.9% (0.2%)
1.1k playouts];
W[de]
C[32.1% (1.0%)
1.0k playouts];
B[eh]
C[68.0% (0.1%)
1.0k playouts];
W[cg]
C[32.2% (0.2%)
1.1k playouts];
B[dh]
C[68.8% (1.0%)
1.0k playouts];
W[ch]
C[31.2% (0.0%)
1.0k playouts];
B[bf]
C[60.2% (-8.6%)
1.0k playouts

I didn't realize that Black can descend here.];
W[ce]
C[20.6% (-19.2%)
1.0k playouts];
B[be]
C[73.4% (-6.0%)
1.0k playouts];
W[bd]
C[21.2% (-5.4%)
1.0k playouts];
B[ee]
C[82.6% (3.8%)
1.0k playouts];
W[cd]
C[14.5% (-2.9%)
1.0k playouts];
B[ci]
C[86.3% (0.8%)
1.0k playouts];
W[bi]
C[10.8% (-2.9%)
1.0k playouts];
B[cj]
C[89.5% (0.3%)
1.1k playouts];
W[ei]
C[10.4% (-0.1%)
1.0k playouts];
B[fh]
C[90.2% (0.6%)
1.0k playouts];
W[bg]
C[9.9% (0.1%)
1.0k playouts];
B[bj]
C[90.6% (0.5%)
1.0k playouts];
W[ae]
C[8.6% (-0.8%)
1.0k playouts];
B[dj]
LB[df:B][ih:A]
SQ[di][ei][fi][gi][dl][dm][dn][fl][fm][eo][fo][fp]
C[91.8% (0.5%)
1.0k playouts 

The result is that the marked stones are captured, and the game is over. 

I was quite embarrassed by my mistakes at A and B, so I decided to continue the game for a little longer.  I knew I was up against one of the best amateur players in the world, so I wanted to learn a few more moves from him (and I sure did).];
W[ed]
C[8.5% (0.3%)
1.0k playouts];
B[hf]
C[91.8% (0.3%)
1.0k playouts];
W[fe]
C[8.7% (0.5%)
1.0k playouts];
B[hd]
SQ[ee][ef]
C[92.3% (0.9%)
1.0k playouts

This is a very good move.  The marked stones are not important anymore.];
W[gc]
C[7.2% (-0.5%)
1.0k playouts];
B[hc]
C[92.9% (0.1%)
1.0k playouts];
W[me]
C[7.9% (0.8%)
1.0k playouts];
B[le]
C[92.1% (0.0%)
1.0k playouts];
W[mf]
C[7.9% (0.1%)
1.0k playouts];
B[lf]
C[91.8% (-0.2%)
1.0k playouts];
W[mg]
C[7.9% (-0.3%)
1.0k playouts];
B[lq]
C[90.5% (-1.6%)
1.0k playouts

His sabaki here was exquisite.];
W[lp]
C[8.8% (-0.7%)
1.0k playouts

I wanted to complicate the game a bit with this move to see what Lee is truly capable of.];
B[pp]
C[92.3% (1.1%)
1.0k playouts];
W[op]
C[7.6% (-0.1%)
1.0k playouts];
B[kp]
C[91.6% (-0.8%)
1.0k playouts];
W[kq]
C[7.9% (-0.5%)
1.0k playouts];
B[oq]
TR[pp][lq][oq]
C[89.0% (-3.1%)
1.0k playouts

There's no way for White to capture the 3 marked stones.  I learned a lot in this fight.];
W[oo]
C[12.0% (1.0%)
1.0k playouts];
B[nq]
C[84.0% (-4.0%)
1.0k playouts];
W[lr]
C[6.9% (-9.1%)
1.0k playouts];
B[qq]
C[93.3% (0.3%)
1.6k playouts];
W[pr]
C[6.6% (-0.0%)
1.0k playouts];
B[qp]
C[94.0% (0.6%)
1.0k playouts

Black achieves a good result here by living in the corner.];
W[ms]
C[4.2% (-1.8%)
1.0k playouts];
B[qr]
C[95.9% (0.1%)
1.0k playouts];
W[os]
C[4.2% (0.0%)
1.0k playouts]
(;
B[pn]
LB[il:C][pn:E][rn:A][po:B][oq:D]
C[95.1% (-0.8%)
55k playouts

White resigns. 

I thought Black would definitely play at A to live, but this move is much better than A.  I felt that I have seen enough of Lee's strength so I ended the game here.  I really respect him for playing complicated but accurate moves at D and E even though he's winning by crushing margins. 

I really wish I played a little better to survive to the second half of the game like I did against Wang Chen of China.  I had a nice sense of shape at C, but I didn't read enough in upper left, which drove me to defeat in just a few moves.];
W[po]
C[If White continues on...];
B[qo];W[rn];B[pm];W[ro];B[mq]
LB[nn:A][ns:B]
C[White is in trouble here.  A and B are miai for Black next.]
)
    (;
    B[rn]
    C[This is inferior to the game for Black.];
    W[rm];B[ro];W[qm]
    C[White gets a nice position on the outside (of course, Black still leads by large margins here).]
    )
)
    (;
    W[dg];B[ji];W[df];B[ge];W[ed]
    C[It's still a complicated game.]
    )
)
    (;
    W[di];B[kn];W[gj]
    C[White can get this nice cap.  White's position here is much better than the game because there's no connection problems on the left side.]
    )
)
    (;
    B[hp];W[ip];B[gn];W[fm];B[hn];W[jq]
    C[This is the same result as the game.]
    )
)
    (;
    B[fr];W[lp]
    C[I had this diagram in mind.]
    )
)
    (;
    W[de];B[ce];W[dd];B[cd];W[ec];B[db];W[md]
    C[White can play like this to press Black on the upper side.]
    )
    (;
    W[jp];B[md]
    C[If White plays the extension, Black will probably turn right away.]
    )
)

