(;GM[1]FF[4]SZ[19]AP[SmartGo:3.0.1]
GN[2017.10.27_AlphaGo_selfplay_13]
PW[AlphaGo]
PB[AlphaGo]
EV[AlphaGo selfplay]RO[13]
KM[7.5]
RE[W+R]
RU[Chinese]MU[1]
C[AlphaGo vs AlphaGo Game 13
Commentary by Michael Redmond 9P
Editing/transcription by Chris Garlock and Myron Souris

This is a very different game, in that there are three corner enclosures. Black isn't playing a kakari, which is different from what human players do now. So we're going to have kind of a workout in how to deal with the large knight's move enclosure. ]
;B[qd];W[dc];B[dq];W[pp];B[cn]LB[ce:A][de:B]
C[This play is unusual in that it is a tight move played by Black.  Black has the advantage of playing the first move, and in an early fight this extra stone should make a big difference.  Black must pay a komi of 7.5 points, and it is believed that Black should play aggressively in the opening to make the most of the initial advantage.]
;W[cf];B[nc]
C[Before there was komi, it was considered good for Black to simplify the opening by making 2 corner enclosures, so this opening is reminiscent of ancient Go.  As mentioned in my comment for Black's previous move, this is thought to be too peaceful for Black in a komi game.  AlphaGo played this opening twice in this 50 game series.]
(;W[qn]
C[White played towards the right side in this game.];B[nq];W[jq]
(;B[pr]LB[qq:A][mp:B][lq:C][jq:D]
C[Black's slide here is an unusual move for AlphaGo to play.  My understanding of it's reason not to play this slide in most cases is that AlphaGo gives a relatively low value to the corner play at A, when comparing with moves from outside such as White moves at B or C.

In this position White already has a stone at D, which reduces the value of playing another stone from outside, and increases the relative value of the corner, making Black's slide feasible.]
;W[qq];B[lq];W[fq]
C[An adventurous move.  It is too wide an extension, but seems to be playable, because White is aiming at a weakness in Black's shimari.]
(;B[hd];W[mp]LB[hq:A]
C[A probe.  White's idea is to play some forcing moves to reduce the value of Black's invasion at A.]
;B[np];W[lp];B[mq]
(;W[qr]LB[hq:A]
C[White's descent is a fairly large move, but in general this play on the second line is not as big as most opening points would be, and is usually played as the first endgame point.  So without some special meaning it is too early to play it now.  The extra value in this case is that this move takes away Black's base, and makes it difficult for Black to invade at A.]
;B[kq];W[jp];B[kp];W[jo];B[ko]LB[hq:A]
C[The two marked stones have become isolated, but it took Black a lot of moves to accomplish that.  There is still some aji of Black's invasion at A, but it is not as threatening as it was before.  The exchange starting with the marked peep has been a success for White.]
TR[mp];W[jc];B[je];W[lc];B[me];W[qf]LB[fq:A][do:B][cq:C]
C[White's move is daring, when White's group on the upper side is in danger.  White is looking at a weakness in Black's shimari, just as when White played at A earlier.

In the lower left corner I showed B as a way to make shape for White's outside group, and C as a way to scoop out the corner that sometimes works.  White has a different move ready for the upper right corner.]
(;B[oe]LB[qi:A]
C[Black protects the corner and looks to attack at A next.  
So while it might look a bit tight, it is actually a reasonable move.]
;W[id]
C[White tries to force a sequence in which White links up to the corner.]
(;B[dd]
C[Black's tsuke here was a move that AlphaGo played a couple of times in the Master series.  In this case, Black is trying to get some forcing moves to set up an attack on the right.]
(;W[ec];B[cc]
C[Looking at the corner only, it might seem that Black's hane is an overplay.  A potential attack against White's group on the side is what makes this move feasible.]
(;W[ed]LB[dd:A][ec:B]
C[White gives Black the corner to protect the upper side.  Black showed good timing with the attack at A, and White showed good judgement with B and the game move here in protecting the weakness on the right.]
;B[de];W[he];B[bd];W[dg];B[qi]
C[Locally, Black's group in the corner is not completely alive, but because the center is open, Black can leave it.]
(;W[ff];B[qm]
C[Black plays away from the upper left corner, which is not fully alive.  This contact play makes the lower right an urgent area also.]
(;W[ql]
C[Clamping here is White's strongest local response.];B[pm];W[rm]
(;B[hq]
C[With unresolved problems in the upper left corner and the right side, Black starts a new fight in the lower left.]
(;W[rk]LB[rn:A]
C[White's big move here removes the threat of Black cutting at A, and reduces Black's potential on the right side.]
;B[gp];W[dp]LB[cq:A]
C[Starting with this attachment, White is planning to crosscut at A, as will happen with White's next move, so this will be similar to when White starts with an attachment at A.]
;B[cp];W[cq]
(;B[cr]
C[When Black plays underneath, the local fight will become a ko.];W[bq];B[dr]
;W[co];B[do];W[bp];B[ep]LB[bn:A]
C[White can live by playing at A and crawling on the second line, but that would be too painful.]
(;W[qc]LB[bn:A][eo:B]
C[Perfectly timed.  White starts to manufacture a ko threat in the upper right corner.

If Black plays at A to kill the lower left corner, White will still have the aji of a cut at B, so Black has no way to cleanly kill White in the corner with a single move.]
;B[rd];W[nd]LB[dn:A]
C[White needs only 1 ko threat for the ko at A, so this fight in the upper right is very troublesome for Black.]
(;B[pc];W[od];B[pd];W[ne];B[md];W[nf];B[mc];W[dn]
C[White finally starts the ko.];B[cp];W[oc];B[bo];W[pb]
C[White's ko threat in the upper right was huge.]TR[oc];B[pg];W[pf];B[of]
;W[og];B[pe];W[ng];B[ph];W[rg]
C[White's ultimate aim in playing this kosumi is to reinforce White's outside group and attack Black on the upper side.]
;B[qb]
C[Black is forced to cut here to protect the corner.  White played at A to induce this move.]
LB[rg:A];W[nb]LB[qb:A]
C[Black A forces White's move, allowing Black to capture White on the right.  White's valuable move gives added security to the group by making a potential connection underneath and weakening the Black group on the upper side.]
;B[rh];W[oi]LB[qj:A]
C[White's move looks to squeeze with a play at A, and increases the scale of White's moyo on the upper side.]
;B[pa];W[ob]
(;B[jl]
C[An important move.  The lower side is starting to look like a territory of about 60 points.]
;W[qj]
C[After White's play here, the right side will be a ko, if Black plays first.]
(;B[di]
C[Black continues to build on the moyo.];W[hk];B[hi];W[il]
(;B[im];W[jk];B[jm];W[kk];B[fi]LB[hk:A]
C[White's invasion at A has succeeded in reducing Black's moyo.  Meanwhile, Black is reducing the size of White's upper side, so it seems to be an even trade.]
;W[hm];B[gl];W[hl];B[hn];W[pi]
C[White captures the 4 stones on the right side.];B[ij];W[ik];B[ig]
C[Black connects to the stones on the upper side.];W[bb]
C[White finally attacks the group in the corner.]
(;B[ch]
C[Black cannot fight the ko, so it sacrifices the corner.];W[be]
C[Capturing the corner, White has established a lead in territory.];B[ki]
;W[rb];B[rc];W[ra];B[se];W[rf];B[re]
C[Black forces here to make eye space for the corner group.];W[ri];B[qa]
;W[gn];B[ho];W[el];B[ie];W[hf];B[kc];W[kb];B[kd];W[ib];B[lb];W[jd];B[fk]
;W[gm];B[if]LB[ke:A]
C[The primary meaning of Black's move is to remove the threat of a cut at A.  Filling a liberty, Black is also creating some aji on the left.]
;W[fo];B[fp];W[oa];B[qc];W[lg];B[lj];W[lk];B[kf]
(;W[ee]
C[White needed this stone to complete the upper side territory.];B[bg];W[bf]
;B[en];W[fl];B[mk];W[ml];B[nl];W[mm];B[nm];W[kn];B[ln];W[lm]
(;B[mn];W[km];B[in];W[fj]
C[White starts to make eyes.]
(;B[ek];W[gj]
C[There are weaknesses in Black's outside shape that make it difficult for Black to kill the center center.]
;B[ka];W[jb];B[gd];W[hc];B[eg];W[ef];B[gb];W[gc];B[ei];W[dm];B[hb];W[ge]
;B[dk];W[ji]LB[eo:A]
C[White can live by playing at A, but can get some extra profit by hitting Black's weak point with this move in the center.]
;B[jh];W[mj];B[nk];W[li]
(;B[kl];W[ll];B[kj];W[jj]
C[White is alive, and has enough territory to win.  Black resigns.])
(;B[kj]
C[If Black connects here, ...]VW[aa:ss];W[jj];B[kh];W[gi];B[gh];W[hh];B[hg]
;W[ii];B[ih];W[eo]
C[... White can capture the marked stone to make an eye with sente.]TR[ij]
))
(;B[gj]VW[aa:ss];W[gk];B[ej];W[kl]
C[This is an example of how White might live.]))
(;B[km];W[mn];B[lo];W[mj];B[nk];W[nn]
C[If Black makes the marked cut, White can cut (marked) and capture the stones on the middle right.]
TR[mj][km]))
(;W[mk]
C[If White plays away, say by extending here, ...];B[ka];W[jb];B[gd]
C[... Black can cause some trouble by extending here.  Black was aiming at this aji with the marked move, which filled a liberty.]
TR[if]
(;W[fd];B[cb]
C[By bumping against Black, White can reinforce from above and still win the semeai on the upper side for now.  But when Black pushes through in the corner, the aji in the corner comes into play.]
TR[fd]
(;W[db];B[df];W[cg];B[ba];W[ab];B[eg];W[ef];B[ad];W[eh];B[fg];W[dh];B[ci]
;W[fh];B[gg]
C[A good reason for White to take Black's eyes by covering with the marked descent is that this gives White good aji on the upper side.  But there is also a negative aspect to this move for White.

When Black plays the marked descent, the corner shape is a 5 stone nakade, which has a lot of liberties and gives Black an advantage in the semeai.  After Black extends here in the center, White's group on the left is in trouble.]
TR[db][ad])
(;W[ad];B[ac];W[ae];B[gb];W[hb];B[ge];W[gf];B[df];W[cg];B[ba];W[ab];B[eb]
C[When one considers the possibility of a semeai on the left side, White's marked hane might seem to be the best way to reduce Black's liberties, while killing the corner group.

But after some forcing moves, with Black's marked attachment, the aji in the corner combines with the semeai on the side.]
TR[eb][ad]
(;W[fe];B[db];W[bc];B[gc];W[hc];B[fb];W[ja];B[eg]
C[When White continues to attempt to kill Black in the upper left corner, Black can connect to the upper side and finally capture White in the center with this hane.]
TR[ab][bc])
(;W[db];B[fe];W[ee];B[ef];W[gc];B[eg]
C[Black's group in the corner escapes.])))
(;W[hc];B[fe]
C[If White plays from the 3rd line, Black can reduce White's territory with this kosumitsuke.]
(;W[ee];B[gf]TR[he:hf]
C[Black captures the 2 marked stones to reduce White's territory.])
(;W[ge];B[hg];W[gf];B[df];W[cg];B[ef]
C[Black's group in the corner breaks out.]))))
(;B[bf]
C[Black can make a ko with this tsuke, but ...]VW[aa:ss];W[bg];B[ce];W[af]
;B[ae];W[be]LB[rb:A]
C[... White takes first, and even has some threats starting with A.  When Black loses the ko, Black's left side will be damaged, so this ko is bad for Black.]
))
(;B[jk]VW[ag:ns];W[jm];B[km];W[ho];B[go];W[hm]
C[When Black plays the marked attack, White can live inside the moyo with this sequence.]
TR[jk]))
(;B[re]VW[ja:ss];W[rf];B[pi];W[pj];B[ri];W[rc];B[rb];W[sh];B[si];W[sf];B[se]
;W[oh];B[qg];W[rj];B[sg]LB[sj:A]
C[White must fight the ko and play at A to get a direct ko, so this is a one move step ko.]
))
(;B[qj]VW[aa:ss];W[jk]
C[Black's marked move is big, but when White plays in the center, White's moyo becomes much larger than Black's.  This is good for White.]
TR[qj]))
(;B[md];W[od];B[pd];W[oc];B[mc];W[dn];B[cp];W[ne];B[nf];W[dp];B[eo];W[of]
;B[pe];W[ng];B[mf];W[pf];B[pc];W[cm]
C[Winning the ko is a huge gain for White.]))
(;W[dn];B[cp];W[qc];B[bo];W[rd];B[jl]TR[dn]LB[pc:A]
C[When White immediately starts the ko (marked), White has no valid ko threat.  White incurs too much of a loss in the lower left corner.  In the upper right, Black can still make shape with moves such as A, so that Black group is not weak.  This is good for Black.]
))
(;B[dr]
C[Black's strongest move.]VW[aj:ls]
(;W[co];B[bp];W[do];B[bo];W[eq];B[cr];W[dn];B[cm];W[fo];B[go];W[fn];B[jn]
C[In this variation, White squeezes the corner to make shape on the outside.  Black gets territory in the corner and the lower side, and I would play this way with Black.]
)
(;W[cr];B[ep];W[do];B[co]LB[eo:A]
C[The ladder at A favors Black.];W[eo];B[fr];W[fp];B[er]
C[Black captures the corner.  This is good for Black.])))
(;W[hp]VW[ak:ls];B[gq];W[gp];B[fr]
C[If White attaches, Black can connect to the corner with this sequence.]
TR[hp])
(;W[gp]VW[ak:ls];B[hp];W[ho];B[go];W[fo];B[gn]LB[hr:A]
C[This fight is troublesome for White.  Black can play at A to connect to the corner or the side.]
))
(;B[rn]
C[If Black cuts here, ...]VW[ja:ss];W[rk];B[sm];W[rl];B[qo];W[pn];B[po];W[on]
;B[oo];W[ro];B[rp];W[sn];B[qp];W[ph]
C[... White will sacrifice the corner and take profit on the side.  This is not bad for White.]
))
(;W[rm]VW[ia:ss];B[ql];W[rl];B[pn];W[qo];B[qk]
C[If White plays the hane underneath, Black will create thickness, and Black's moyo on the right becomes deep.]
TR[rm])
(;W[pm]VW[ja:ss];B[ql];W[rn];B[pl]
C[If White plays a hane on top, Black will pull back and curl here, building on the right side.]
TR[pm])
(;W[bb]VW[aa:jj];B[bf];W[bg];B[ce];W[af];B[ae]
C[If White attacks the upper left corner (marked), Black can still make a ko with this sequence.  For the time being, Black's marked attack makes the lower right more important.]
TR[bb][qm]))
(;W[bb]VW[aa:jj];B[cb];W[be];B[ba];W[ab];B[ee]
C[The corner is not fully alive, but Black can escape into the center.]))
(;W[cd]VW[aa:ms];B[ce];W[bd];B[ed]
C[If White cuts, Black will sacrifice the stone in the corner and threaten to force from one side or the other.]
TR[cd]
(;W[be];B[fc];W[cb];B[ie];W[hc];B[gc]
C[When White defends the corner (marked), Black has accomplished little in the corner, and this would usually be the answer for why the whole sequence here is bad for Black.  However, in this case where White has a weak group on the side, Black's marked forcing move makes a huge difference in the upper side fight, and this is good for Black.]
TR[fc][be])
(;W[fd];B[be];W[bc];B[df];W[fe];B[ef];W[he];B[dj]LB[fc:A][ie:B]
C[White can take the upper side, but Black gets a good position on the left.  With aji for cuts at A or B, Black still has potential to reduce the upper side.  This is good for Black.]
)))
(;W[cd]VW[aa:sm];B[ec];W[de];B[ed];W[db];B[cc];W[cb];B[bc];W[bb];B[hc];W[ie]
;B[ff];W[jf];B[dg];W[cg];B[qi]
C[When White answers from the corner, Black can force from the right and take White's base away with the marked descent.  Later Black can continue to attack with a play at A, and this looks good for Black.]
TR[hc]LB[ke:A]))
(;B[ie]VW[aa:si];W[hc];B[gd];W[gc];B[fd];W[fc]LB[id:A]
C[White A was a vulgar-looking move, but if Black answers (marked), White can make territory on the 3rd line while connecting to the corner.  This is good for White.]
TR[ie]))
(;B[hb]VW[aa:sm];W[oc]
C[When Black attacks, White's move here is the tesuji for this position.  White threatens to break open the corner or save the side group.]
(;B[od];W[pc]
C[If Black plays the hane, White's move makes miai of cutting off the corner or connecting on the side.]
(;B[nd];W[nb];B[mb];W[ob];B[mc];W[pd];B[pe];W[qe];B[qc];W[pf];B[oe];W[qb]
;B[rb];W[ra];B[rd];W[sc];B[pa];W[qa];B[na];W[pb];B[sb];W[re];B[sd];W[se]
;B[rc];W[pi]LB[ke:A]
C[The corner ends with a seki.  White has a good position on the right, and there is still some aji at A.  This is good for White.]
)
(;B[pd];W[nb]
C[White lives while taking the corner, and this is bad for Black.]))
(;B[mc]
C[Black's move stops White from connecting on the side, and I would play here.]
;W[od];B[pe];W[ne];B[ld];W[nf];B[pf];W[pg];B[qg];W[qh];B[rg];W[ph];B[rf]
;W[mf]
C[White's marked move is the tesuji to break out into the center.  And after White turns here, Black needs to add another move to the upper side.  White can be satisfied with this result.]
TR[ne])))
(;W[kq]VW[aj:ss];B[qr]LB[hq:A]
C[White's marked move might seem to be natural, but Black is alive and White has not removed the threat of Black's invasion at A, so this is not good for White.]
TR[kq]))
(;B[hq]VW[ai:ss]
(;W[cq]
C[White's tsuke here is a tesuji often used against Black's ogeima shimari, but one must be careful, as it can involve a ladder or a ko.]
;B[cp]
(;W[dr];B[cr];W[bq];B[er];W[dp];B[eq];W[co];B[do];W[bp];B[ep]LB[dn:A]
C[In this variation, White needs a ko threat for the ko when White cuts at A.  At this time, White has no valid ko threat.]
)
(;W[dp];B[dr];W[cr];B[ep];W[do];B[co]LB[eo:A]
C[White tries to create a squeeze with the marked play, but this involves a ladder at A, which favors Black.]
TR[cr];W[eo];B[fr];W[fp];B[er]
C[This is good for Black.]))
(;W[do];B[co];W[dr];B[cq];W[fo]
C[The marked plays are a sequence that White can use to reduce Black's corner territory and make shape for White outside.  This is how I would play with White.]
TR[do][dr])))
(;B[pq]
C[AlphaGo usually plays this attachment.]VW[ah:ss];W[qq];B[qr]
C[The marked tsuke and hane is what AlphaGo usually plays.]TR[pq][qr];W[oq]
;B[pr]LB[oq:A]
(;W[or];B[op];W[nr];B[qp];W[po];B[rp];W[mq]
C[When White pushes through (marked), Black will take the corner, while White gets outside thickness.  This is an even trade.]
TR[or])
(;W[op];B[or];W[rq]
(;B[np];W[mr];B[nr];W[gq]
C[Black's marked push is the move that AlphaGo usually plays in connection to this joseki, but in this case it is bad for Black when White peeps (marked) and then extends on the side.]
TR[np][mr])
(;B[lq];W[fq]LB[np:A]
C[I have not seen AlphaGo play Black's marked extension with this joseki, so it could be that it considers this bad, and prefers to push at A with this move.]
TR[lq]))))
(;W[nq]
C[In game 17 AlphaGo with White played towards the lower side.]VW[aa:ss]
;B[qn];W[qo];B[pn];W[pj];B[mn];W[mp];B[qh]
C[This sequence was played in game 17 of this series, and it looks normal to me.  I could imagine human pros playing the same moves.]
))

