(;GM[1]FF[4]SZ[19]AP[SmartGo:3.0.1]
GN[AlphaGo_selfplay_06]
PW[AlphaGo]
PB[AlphaGo]
EV[AlphaGo-AlphaGo]RO[Game 6]
KM[7.5]
RE[W+Resign]
RU[Chinese]ST[2]
AN[Michael Redmond 9P]
C[AlphaGo vs AlphaGo Game 6: commentary by Michael Redmond 9P

In this game AlphaGo shows its flexibility when Black abandons a running fight and tries to control the open lower side of the board instead. In the second fight of the game, White deals with two weak groups masterfully. Finally, Alphago shows its bias for complications when White allows a dangerous ko in the corner. ]
MU[1];B[pd];W[dc];B[pp];W[dq];B[de];W[ce];B[cf];W[cd]
(;B[df]
C[This is an opening that happens again and again; the Ke Jie version of AlphaGo almost always plays this solid connection. Against Lee Sedol, AlphaGo played a hanging connection, but it doesn't do that anymore. 

]
(;W[fc]
C[If White plays away, say at A, Black will follow up immediately in the upper left (see var)]
LB[cn:A]
(;B[co]
C[AlphaGo rarely plays the joseki move to extend on the side (A; see variation), instead playing the kakari, inviting White to pincer. ]
LB[dj:A]
(;W[fp]
C[For AlphaGo, white's keima is the most common response to Black's kakari. ]
(;B[dl]
C[This is also a move we're going to be seeing in a number of these games. A human player would prefer to play at A (see var), but that leaves a weakness at B later. ]
LB[dk:A][cm:B];W[dj]
C[A human player wouldn't want White to invade. Black would be a bit worried about it, but AlphaGo is welcoming it.  ]
;B[gf];W[fj]
C[Black's play on the side is hard for me to understand. Black apparently judges its groups on the left side to be strong, and invites White to invade at 14, after which Black does not even try to attack. ]
(;B[hq]
C[I would want to try to attack White's group on the left, but AlphaGo takes the big point on the lower side with 17. While this is a flexible and balanced move that is representative of AlphaGo's style, it seems inconsistent to abandon the running fight from the left, as Black has spent a number of moves setting that up. This is a position in which I think I could learn a lot if I had direct access to the network data to see value network scores and policy network variations for various moves. ]
;W[fm];B[hm]
C[Black 17 and 19 were both surprising moves, allowing White to surround the left side group, just what I didn't want to happen. Black 19 threatens to cut White in the center. ]
(;W[cm]
C[If White protects at A, Black can live and create a potential moyo on the lower side (see var). Attacking from the corner at B doesn't work, either (see var). Since playing at A is too dangerous and B is a bit too submissive, W20 is a nice move, making the side position more urgent. ]
LB[el:A][cp:B];B[en]LB[cp:A][el:B]
C[The fight is going to turn good for White, so Black is dodging around a bit here. ]
;W[cl];B[go]
C[Black continues to play kikashi from outside before living in the corner. ]
(;W[do]
C[W24 is a nice, thick move. ];B[cp]
C[Finally, Black tries to live in the corner. Trying to kill at A is a bit of an overplay (see var). ]
LB[cq:A]
(;W[dp];B[cq];W[cr];B[br];W[dr];B[bn];W[dn];B[ei]
C[Black plays away, but the corner is a well-known tsumego that becomes ko. It has been said that go-playing AIs have trouble understanding complicated local positions, so did AlphaGo make a mistake? Maybe the corner is just not big enough at this point. ]
(;W[fi]
C[Locally, White can play at A to make a ko to kill the Black group; Black can attempt to connect on the left side, but it does not seem to work in this position (see 78-move var). ]
LB[bs:A];B[kq]
C[At this point of the game, this is a bigger point, but the interesting thing is that both players left this lower-left corner to the endgame. I think that's taking it leaving it alone to an extreme that's further than I would go. It's 30 points locally but because it's a ko we would usually say it's worth 20. So B35 is definitely bigger right now but there are definitely points in the game where I wish AlphaGo had gone back to settle the corner. ]
;W[qn];B[ro]
C[Black 37 is a strong move that denies White access to the corner and prepares to expand Black's moyo on the lower side. ]
(;W[lp];B[kp];W[ln];B[oo];W[nm];B[pm];W[pk]
C[White offers to sacrifice the marked stone...]TR[qn];B[ok]
C[But Black declines, attacking the center White group strongly.];W[pl]
C[White 46 is a strong counter-attack. In this fight, White will be trying to build territory on the right side, and make light sabaki for White's group on the lower side. ]
(;B[mm]
C[Black 47 is a really fancy move, an effective way for Black to cut White off in the center. Playing at A would permit White to squeeze from outside (see var).]
LB[ol:A]
(;W[lq];B[lo];W[mo];B[ko];W[mn];B[om]
C[White starts with 48 to induce the sequence to 52. Compared to simply playing at 52, by playing 48 first White has gained a foothold on the lower side and now has some potential to put pressure on the Black group on the left. Black cuts with 53, and White must avoid a direct confrontation here. ]
(;W[lr];B[jm];W[kr];B[jr];W[pi]
C[With the 54~57 exchange White created some eyespace on the lower side, enabling White to switch to the right with 58. ]
;B[np];W[oq]
C[This is where it gets a bit exciting. White answers Black's peep indirectly with 60, offering a trade of the LR corner for the side. ]
(;B[pq]
C[The cut at A is the strongest local move, leading to a trade (see var). ]
LB[mp:A];W[mp];B[nr];W[jn];B[kn];W[lm];B[ol];W[km]
C[White 64~66 was an important order of moves, making the cut at 68 effective. ]
(;B[iq];W[jl];B[im];W[qf]
C[This fight has gone according to White's plan, in that White has surrounded the right side while saving the lower side group. The game looks promising for White now. ]
;B[oj];W[pj];B[qe];W[rf];B[qm];W[re];B[lc];W[bs];B[ar];W[qc]
C[Taking the UR corner with 82, White has a lead in territory. ];B[pc];W[qb]
;B[jj];W[nq];B[or];W[kk];B[hc];W[ik];B[ij];W[hk];B[kj];W[gm]
C[As White connects with 94, the lower side of the board has only endgame moves left, apart from the ko that White can make in the LL corner. The upper side has an unsettled Black group on the left and some space for Black to make territory, so it is the important area now. ]
;B[gd];W[fd];B[fe]
C[Black 95-97 is a thick move, connecting to the left and preparing to surround the upper side. ]
;W[he];B[hf];W[le]
C[White plunges into an area that might seem to be dominated by Black, but actually Black is not very strong in the upper right. ]
;B[em];W[fn];B[ej];W[ek];B[dk];W[el];B[og]
C[There are some weaknesses in Black's shape that make it difficult for Black to cut White off with this move. ]
(;W[nh]
C[Playing once at 108 before attacking Black's weakness on the upper side is the correct order of moves. ]
(;B[pf];W[mg];B[je];W[qd]
(;B[pe];W[lj];B[oi];W[ph];B[oh];W[li];B[kh];W[ki];B[gb]
C[The ko in the LL corner has disappeared, and one might think we are heading into a peaceful endgame. ]
(;W[fb];B[bf];W[ci]
C[White 124 is big in territory, and sets up to play the ko in the LL corner. ]
(;B[bc]
C[When Black plays at 125, it is normal for White to avoid a ko in the UL corner. ]
(;W[ad]
C[White 126 is a dangerous move, allowing Black to make a ko of the UL corner. Does AlphaGo as White think that the safe move is not good enough, or is this an example of this version's extravagant love of complicated positions and ko fights? ]
;B[cc];W[dd];B[db]
C[White cannot avoid a ko now. ]
(;W[eb];B[bb];W[ca];B[da];W[ba];B[jh];W[lh];B[ac];W[bd];B[aa]
C[A big ko starts in the UL corner. A human player as White would avoid this, so why did AlphaGo choose this path? ]
;W[ab];B[qg];W[pg];B[aa];W[ee];B[eh];W[ab];B[rd]
C[Black 147 threatens another ko on the right side. ]
(;W[rg];B[aa];W[fh];B[ef];W[ab];B[cj];W[di];B[aa];W[gc];B[hb];W[ab];B[ck]
C[When Black connects at 159, White must be careful to reduce the number of Black's ko threats. ]
(;W[dm]
C[White 160 takes a local loss but reduces the number of valid Black ko threats. ]
;B[aa];W[ge];B[ff];W[ab];B[fk];W[fl];B[aa];W[hd]TR[jd]
C[White 168 is a ko threat that threatens to escape with a play at the marked point. ]
;B[bi]
C[Black has run out of ko threats, and takes the largest point with 169. ]
;W[ch];B[bh];W[ab];B[cg]
C[When Black captures with 173, the LL corner is alive. ]
(;W[pb];B[aa];W[ic];B[id];W[ab];B[ie];W[cb]
C[The ko finally ends. Black has gained a lot on the left side, and the game is close. ]
;B[ob];W[gd];B[jc];W[nb];B[oc];W[oa];B[rc];W[rb];B[pa];W[qa];B[rk];W[rj]
C[Black's shape in the center has a weakness. ]
(;B[kg];W[rl]
C[Black should answer on the right side. ]
(;B[mb];W[rm];B[rn];W[hn];B[in];W[ho];B[io];W[hp];B[ip];W[gq];B[gr];W[fq]
;B[ml];W[lk];B[sm];W[qk];B[fr];W[ne];B[nc];W[kf];B[jf];W[hh];B[ih];W[nn]
;B[mk];W[bk];B[bj];W[er];B[fg];W[hj];B[hl];W[gk];B[op];W[mq]
C[White has a small lead. ]
(;B[bm];W[bl];B[mf];W[nf];B[lf];W[lg];B[ke];W[me];B[kf];W[ng];B[gp];W[gn]
C[White is ahead by 1.25 stones, or 2.5 points. ])
(;B[mf];W[nf];B[lf];W[lg];B[ke];W[me];B[kf];W[ng];B[ld];W[bl];B[an];W[on]
;B[pn];W[fs];B[hr];W[ga];B[ib];W[hg];B[ig];W[ed]
C[W+1.25 stones (2.5pts)]))
(;B[rm]
C[Black 1 is the biggest move. ]))
(;B[qk];W[ji];B[ih];W[ii]
C[White can push through with 2-4 to capture three Black stones in the center. ]
))
(;W[bk];B[bj];W[bp];B[ap];W[ao];B[bq];W[aq];B[bo];W[ap];B[an];W[ap];B[ak]
;W[bl];B[al]
C[Black can connect on the side.]))
(;W[bi];B[aa];W[ge];B[ff];W[ab];B[rc];W[rb];B[aa];W[hd];B[jc];W[ab];B[bm]
;W[bk];B[aa];W[ic];B[ib];W[ab];B[fk];W[fl];B[aa]
C[Locally, White 1 is the strongest move, but it allows Black too many ko threats on the left side. ]
;W[if];B[ie];W[ab];B[bl];W[bj];B[aa];W[af];B[ag];W[ab];B[cn];W[dm];B[aa]
;W[bg];B[ae];W[ab];B[mk];W[lk];B[aa]
C[White runs out of ko threats to lose the ko and the game. ]))
(;W[cb];B[rg];W[rc];B[ri];W[rj];B[rk];W[sj];B[qh];W[qi];B[sh];W[si];B[sk]
C[The right side becomes a ko. ]))
(;W[ea];B[bd];W[be];B[bb];W[da];B[ca];W[ac];B[ab];W[ae];B[eb];W[fa];B[gc]
;W[ba];B[aa];W[ec];B[ga];W[cb];B[db];W[eb];B[af]
C[When White tries to kill Black with the kosumi at 1, the semeai results in a ko with the sequence to 20. This is bad for White. ]
))
(;W[cc];B[ad];W[bb];B[ab];W[ba];B[af];W[db]
C[White can avoid a ko with this sequence, and White has a lead in territory. My human judgment is that this is the safe play, and that it is good enough for White. ]
))
(;B[pb];W[bp];B[ap];W[ao];B[bq];W[aq]LB[ci:A]
C[Because of White's stone at A, Black cannot connect on the side and has no choice but to fight this ko. ]
))
(;W[bp];B[ap];W[ao];B[bq];W[aq];B[an];W[ap];B[bk];W[bl];B[al]
C[In this position, Black can avoid the ko and connect to the upper left with 6-10. ]
;W[bj];B[ck];W[cj];B[dm];W[cn];B[bo];W[ap];B[di];W[ch];B[dh]
C[Black captures White on the left side. ]))
(;B[lk];W[hn];B[in];W[il];B[pe];W[io];B[jo];W[hl]
C[At this point Black can live by sacrificing four stones, but the loss in territory is too big to justify Black's play at 1. ]
;B[jn];W[jq];B[jp];W[ip];B[jq];W[gn];B[ho];W[gr]LB[lk:A]
C[Black has a forcing move at A, but cannot use it because it allows White to set up this sequence to kill the Black side group. ]
))
(;B[ng];W[oe];B[pe];W[pf];B[of];W[ne];B[nc];W[mg]LB[nh:A]
C[By exchanging A for Black 1 before playing at 2, White has forced Black into bad shape in the center. ]
;B[oh];W[oi];B[mf];W[mh];B[me];W[lf];B[md];W[lj]
C[Black has captured two stones, but now White is ready to take the offensive in the center. This is good enough for White. ]
))
(;W[oe];B[pe];W[pf];B[of];W[ne];B[nc];W[nh];B[oh];W[oi];B[mf]
C[When White immediately plays at 1, Black will cut with 2-4 and then Black has good shape with the jump at 10. Black will profit in this fight. ]
))
(;B[jl];W[jq];B[jp];W[iq];B[ip];W[ir];B[hr];W[js]TR[hp]
C[If Black extends at 1, White can cut at 2 to make eyeshape, and White still has the marked cut. This is good for White. ]
))
(;B[mp];W[pq];B[qq];W[qr];B[mr];W[qp];B[nr];W[qo];B[qm];W[qf]
C[While Black captures the side, White's profit in the corner is also fairly big, so I will call this an even result. ]
))
(;W[ol];B[nl];W[nn];B[qm];W[nk];B[ml];W[kl];B[lk];W[oj];B[kk]
C[White is cramped on the lower side. ]))
(;W[mn];B[om];W[ol];B[nl];W[nn];B[qm]
C[Black cuts White in the center, ending with the large move at 6. White will have trouble dealing with two weak groups. Despite the seemingly thin position outside, Black's position is actually very resilient, as White cannot capture the key stone (marked). ]
TR[nl]))
(;B[ol];W[om];B[pn];W[oj]
C[White 4 is the vital point to give Black bad shape. ]
(;B[ml];W[mk];B[nl];W[ll];B[mm];W[mn];B[nn];W[lm];B[on];W[pi]
C[Black has not gained much by taking the two stones, and this is good for White. ]
)
(;B[nk];W[lk];B[mj];W[qg]
C[This variation displays White's plan to surround on the right while escaping with the lower side group. ]
)))
(;W[pj];B[on]
C[When White extends at 1, Black 2 works well with the overall position to create a moyo on the lower side. ]
))
(;W[bs]
C[Locally, White can make a ko to kill the Black group; Black can attempt to connect on the left side, but it does not seem to work in this position (see 78-move var). ]
;B[ar];W[bp];B[ap];W[ao];B[bq];W[aq]
C[Locally, White can make a ko to kill the Black group with the sequence to 7. I explored a sequence with which Black attempts to connect on the left side, but it does not seem to work in this position.]
;B[an];W[ap];B[bk];W[bl];B[al];W[bj];B[ck];W[dk];B[cj];W[ci];B[ak];W[bh]
;B[di];W[bf]
C[When Black tries to connect on the side, White can cut Black off and connect to the corner. ]
;B[bi];W[ai];B[ch];W[bi];B[bg];W[ag];B[cg];W[be];B[am];W[af]
C[Black uses this forcing sequence on the side to extend the liberties of Black's corner group. ]
;B[el];W[fk];B[em];W[gp];B[hp];W[gr];B[hj];W[hk];B[ik];W[ij];B[hi];W[gm]
;B[fo];W[hn]
C[In the end, White lives on the lower side and can escape in the center. The status of this variation will change as trhe game progresses and stones are added in the center, but for the time being this is good for White. ]
))
(;W[cq];B[dp];W[ep];B[dn];W[fn];B[fo];W[eo];B[cn]
C[If White attacks from the corner with 1, Black continues with 2-8, threatening to attack in the corner or capture the two cutting stones. ]
(;W[fr];B[fl];W[gl];B[fk];W[gk];B[gm]
C[Black captures the cutting stones. ])
(;W[el];B[bq];W[br];B[eq]
C[White collapses in the corner. ])))
(;W[gp];B[hp];W[fo];B[cq];W[cr];B[dr];W[cp];B[bq];W[dp];B[er];W[bp];B[br]
TR[fl]
C[If White cuts with 1 and 3, Black can live in the corner with the sequence to 12. Black still has some aji with an attachment at the marked point. ]
))
(;W[el];B[go];W[fo];B[cq];W[cr];B[bq];W[dp];B[bl]LB[hm:A]
C[If White protects at 1, Black can live with the sequence to 8. By forcing from outside with moves such as A, Black has created a potential moyo on the lower side, and this is not bad for Black. ]
)
(;W[cp];B[bp];W[bq];B[dp];W[cq];B[fl];W[gl];B[fk];W[gk];B[gm]
C[When White attacks fron the corner with 1, Black can cut in the center with 6-10. This creates a double threat to cut in the center or capture the White cutting stone. ]
;W[fn];B[gj];W[el];B[ek];W[dk];B[em];W[ej];B[el];W[il];B[gi];W[ij];B[ck]
;W[cj];B[bk]
C[White's group on the left side is in trouble now. ]TR[cj:fj][dk]))
(;B[fl];W[hj];B[gd]
C[The 'human' move would be to cut White off with 1, and then strengthen Black's UL group with 3. I expect that Black will have opportunities to attack White in the center.]
))
(;B[dk];W[qq];B[qp];W[pq];B[nq];W[oq];B[op];W[nr];B[ge];W[cm]
C[Black's extension at 1 seems to make a good connection on the left side for Black, and many human players would choose this move. However, this leaves an invasion at 22 which will be troublesome after Black tries to expand the moyo with 21. ]
LB[dk:A]))
(;W[dk];B[ep];W[eq];B[fp];W[gq];B[gp];W[hq];B[hp]TR[ep]
C[AlphaGo attaches a large value to the marked pressing move, and apparently judges that Black has an advantage in this fight. My honest opinion is that I don't know, but it looks normal enough for me to try it in my own games. ]
))
(;B[dj]
C[AlphaGo rarely plays the joseki move to extend on the side. My hypothesis at this time is that AlphaGo judges the UL Black group to be fairly strong and is inviting a fight on the left, and that compared to this extension, it gives a higher value to the big opening points, such as a kakari in the LL. ]
))
(;W[cn];B[ec];W[eb];B[fb];W[ed];B[fc];W[dd];B[ge];W[db];B[cj]LB[df:A]
C[When Black connects solidly at A and White plays away, Black can play strongly with the hane at 4 and the keima at 8 to control the upper and left sides efficiently. Fan Hui showed this as AlphaGo's intended continuation, and suprisingly, this is exactly the same as a sequence the great player Go Seigen 9P once showed me at his study group. Go Seigen's ideas were difficult for most pros to understand, but ultimately had a huge impact on how we play the opening. I think we can re-discover the value of Go Seigen's teachings when finding these similarities to AlphaGo. Like AlphaGo, Go Seigen's game was very flexible, very fluid, he wasn't obsessed with being so consistent, as so many top players are. His games changed a lot in mid-stream, and there's something very beautiful about that.  ]
))
(;B[co];W[df]
C[Apart from the 50 self-played games, 5 self-played games with the same version of AlphaGo were released in China and made into videos on Weiqi TV. With a top Chinese pro commentating, Fan Hui 2P was also there to give some inside data from AlphaGo's networks, and this is one of the variations he showed in this same board position. When Black plays a kakari with 1, AlphaGo considers the cut at 2 to be important. ]
(;B[ep];W[eq];B[fp];W[gq];B[cg];W[ef];B[di];W[qc]LB[co:A]
C[Ending with a characteristic invasion to the 3-3 point, this variation shows how the Ke Jie version of AlphaGo thinks the game will proceed after Black's kakari at A. ]
)
(;B[cg];W[ef];B[fp]
C[What happens if Black plays the taisha in the LL corner? The top pro analyst Tan Xiao 9P had this question, but Fan Hui had not taken that data and could not give a full answer. ]
)))

