The Magic of Kifu

(;GM[1]FF[4]CA[UTF-8]AP[CGoban:3]ST[2] RU[Chinese]SZ[19]KM[7.50]TM[7200]OT[3x60 byo-yomi] PW[Lee Sedol]PB[AlphaGo]WR[9p]DT[2016-03-10]C[Game 2 - Invention Commentary by Fan Hui 2p Expert Go analysis by Gu Li 9p and Zhou Ruiyang 9p Translated by Lucas Baker, Thomas Hubert, and Thore Graepel AlphaGo's victory in the first game stunned the world. Many Go players, however, found the result very difficult to accept. Not only had Lee's play in the first game fallen short of his usual standards, but AlphaGo had not even needed to play any spectacular moves to win. Perhaps the first game was a fluke? Though they proclaimed it less stridently than before, the overwhelming majority of commentators were still betting on Lee to claim victory. Reporters arrived in much greater numbers that morning, and with the increased attention from the media, the pressure on Lee rose. After all, the match had begun with everyone expecting Lee to win either 5-0 or 4-1. I entered the playing room fifteen minutes before the game to find Demis Hassabis already present, looking much more relaxed than the day before. Four minutes before the starting time, Lee came in with his daughter. Perhaps he felt that she would bring him luck? As a father myself, I know that feeling well. By convention, the media is allowed a few minutes to take pictures at the start of a major game. The room was much fuller this time, another reflection of the increased focus on the match. Today, AlphaGo would take Black, and everyone was eager to see what opening it would choose. Whatever it played would represent what AlphaGo believed to be best for Black. Perhaps that opening would become the new fashion in the Go world?]RE[B+Resign] ;B[pd]C[Unlike the first game, AlphaGo played its first move after less than thirty seconds. Rarely does it decide so quickly.] ;W[dp]C[Lee played White 2 in the lower left corner, on the diagonally opposing star point, indicating a strategic departure from the first game. Since the fighting had turned against him before, perhaps he wished to play a quieter and more solid opening this time. In that case, White 2 may have aimed to prevent AlphaGo from taking that point for Black, since this kind of cross-opening can easily turn violent.] ;B[cd]C[When Black played the 3-4 point, I felt that AlphaGo would opt for the Chinese opening, one of its favorites.] ;W[qp]C[Compared to the first game, Lee played much more slowly, pondering over each move. Many players had criticized him for playing too quickly in the first game, and the shift may have been partly in response to that. Sometimes changing pace is also a useful meta-tactic to disrupt the opponent's mindset, but of course this would have no effect on AlphaGo.] ;B[op]C[White took the remaining 3-4 point, and AlphaGo approached the lower right corner with 5.] ;W[oq]C[I had heard that Lee was very fond of coffee, and always asked the staff to bring more as soon as his cup was empty. During this game, and the rest of the match, he fully lived up to his reputation.] ;B[nq] ;W[pq] ;B[cn] ;W[fq] ;B[mp] (;W[qn]C[Through here, everything proceeded normally.] ;B[ic]LB[qn:A]C[Black 13 came as an enormous surprise. Even here, Black can tenuki? It seems anything is possible for AlphaGo! Just as interesting, AlphaGo did not even think White should have finished the joseki at A! See the variation. Gu Li and Zhou Ruiyang were just as shocked as I was by this revelation, and we began to wonder: could there be a problem with even such an established, fundamental joseki as this? Here, AlphaGo’s win rate was 49.7%, so it thought the game more or less in equilibrium.] (;W[dj]C[After seeing Black 13, Lee sank into deep contemplation. Compared to his confident appearance in game 1, he now seemed much more prudent. He even declined the opportunity to attack the three stones in the lower right, opting instead to bide his time and split the left side. However, AlphaGo thinks Black should have played at the bottom as shown in the variation.] ;B[po]C[The peep at Black 15 stunned the Go world for the second time in two moves! Any Go teacher would say that such a crude move cannot possibly be good, and would criticize any student who played it. Then again, AlphaGo never worried about other people's opinions. As we walk the path of improvement, we must study and experience all aspects of the game: joseki, fuseki, shape, and direction, just to name a few. After we absorb this knowledge, we learn over time to apply it flexibly. But to reach the level of grandmasters, even this is not enough! As we gain experience, our knowledge fetters our creativity. To truly throw off these shackles and liberate ourselves from what we have learned, we must discard labels of "right" and "wrong." In their place, we must consider the essence of Go: the role of each stone, and the relationships between them. Only in this way can we reach the level where invention prevails over tradition. AlphaGo began from the same fundamentals as humans, but the rigid attachment to knowledge is simply not in its nature. Thus, it is only natural that AlphaGo possesses a talent for creativity. In the history of Go, I can think of two periods when a decisive shift occurred in Go theory. The first was the age of Go Seigen. The most famous example of his innovation is perhaps the game in which he opened on the star point, the tengen, and the 3-3 point, in a time when no other professional player would think of starting anywhere besides the 3-4 point. But beyond that, he showed us that Go, even at the highest level, can be played in any style one likes. Out of that age of 3-4 points, a hundred other styles blossomed and grew, including the Chinese opening we know today. However, many joseki and fuseki still remained purely theoretical. The second such period was the age of Lee Changho and the Korean style. This movement was by no means the work of one person, but it was Lee Changho's rise that inspired Korean players to doubt established theory, and experiment with ever-bolder departures from the prevailing style. At first, many of these moves were called "crude" or simply "bad," but the results spoke for themselves. As research progressed, many older joseki were disproved and discarded. We realized that many of these joseki had been established not by study, but by old grandmasters who had claimed that one way or another was the right one. The more we explored the new variations, the more fatal weaknesses were exposed in the old ones. These discoveries liberated us, stimulating the development of more and more new styles and variations. In the final analysis, this period marked a great advancement in our understanding of Go, simply because we had the courage to try new things. However, the emergence of the Internet has stimulated ever-faster development and progress. As the strength gap between players shrinks, so too does the apparent window for innovation. But Go is a rich, abundant world - can we truly say that we have reached its limits? Perhaps AlphaGo can usher in a third wave of exploration and invention. When we are brave enough to defy theory, only then can we Go players call ourselves "free." Even from the perspective of amateurs and fans, wouldn't this spirit make Go that much more fascinating to witness? In fact, it is gratifying to note that since AlphaGo played 15, more and more professionals no longer find it so crude. Quite often, professionals find themselves wanting to exchange this move after the opportunity has disappeared, so many players have started trying to work it in earlier. It seems we have already gained some courage!] ;W[qo] ;B[cp] ;W[cq] ;B[bq]C[In the lower left, Black played more normally, choosing the standard moves to settle the corner.] ;W[co] ;B[bp]C[When Black connected with 21, Lee nodded. He seemed to be reaffirming his decision to play on the left side.] (;W[bo]C[White chose to block, but AlphaGo prefers the connection shown in the variation.] ;B[do] ;W[bn] ;B[dq] ;W[ep] ;B[dr] ;W[cm]C[Up to here, the moves in the lower left form a classic joseki.] ;B[jp]LB[iq:A]TR[dr]C[Taking the initiative on the bottom, AlphaGo once again smashed convention with the beautiful two-space jump at 29! According to Nie Weiping, when he saw this move, he exclaimed, "Hats off to AlphaGo!" The rationale behind this move is not difficult to understand: since Black already has the marked stone in the corner, the lower side has lost much of its value, and the normal extension at A would be less efficient in view of White's thickness on the left. Furthermore, although Black 29 takes less territory than A, it gives Black more potential to expand in the center while restricting White's influence there. The real beauty of this move lies not just in the move itself, but in the way it demonstrates AlphaGo's ability to adapt joseki according to context. It is this sense of flexibility that deserves recognition. At this point, Lee Sedol had 1 hour and 40 minutes left, AlphaGo 1 hour and 43 minutes.] (;W[cg] ;B[ed]LB[ed:B][cg:A]C[The exchange of A for B looks normal, but AlphaGo's win rate clearly increased, so it must think this benefits Black! See the variation.] ;W[qf]C[After Black enclosed the corner, Lee Sedol briefly hesitated over the direction of play in the upper right. He eventually chose to approach from below.] (;B[qe]C[The kick at 33 was a good choice for Black. White was already solid on the right, so the loss from strengthening White further was minimal, and 33 prevented White from invading the corner. See the variation. ] ;W[pf] ;B[nd] ;W[pi]C[Up to here, both sides played normally.] (;B[oj]LB[qn:A]C[Black 37 is one of the two moves from this match sure to go down in Go history. This move proved so stunning that, when it appeared on the screen, many players thought the stone had been put down in the wrong place. Because my main duty was to count the score at the end of the game, I had nothing in particular to do in the meantime. However, for such a historic event, it would be a terrible shame if there were no one to record the scene in the playing room, so I took this role upon myself. Though I had no prior experience, my aim was simple: to capture the atmosphere, the players' expressions, even their gestures, and in this way to communicate the experience of the match. On seeing Black 37, I wrote down the following: "Here?! This goes beyond my understanding. Globally, there's nothing wrong with it, it's going in the right direction...and AlphaGo always pays special attention to coordinating the stones. It seems anything is possible in Go! Everyone will be talking about this move! A human would never dare play it, it's too difficult to estimate. But AlphaGo can. Perhaps this move is a sign of its confidence." This move made a deep impression on me during the game. I experienced first confusion, then shock, and finally delight. It reminded me of an old Chinese saying: "A beginner plays the corners, an average player the sides; but a master controls the center." These days, due to the convergence of strengths and the pressure of competition, something close to the opposite is true, with most players focusing on the corners and sides. In contrast, AlphaGo's talent for central control is second to none. Perhaps, through AlphaGo, we too can become the "masters" of which the proverb speaks. Returning to the game, we may say that Black 37 casts an invisible net across the board. Together with the lower side, Black's shoulder hit creates potential all across the center. Although it helps White make territory on the right, the presence of White A means that a Black invasion there would not have been valuable anyway. Of course, Black should be reluctant to give away fourth-line territory too easily, but one must give to get. After the match, when I examined the data back at DeepMind, I saw that AlphaGo had not even been thinking about 37 only a few moves before. It had been expecting diagram 6, and its data indicated that a human player would hardly consider the shoulder hit a possibility. It was only when White played 36 that AlphaGo discovered 37, and boldly decided that this move would work even better. The pace of the game was much slower than the previous day, so Lee had already gone out to smoke before 37. The minute he caught sight of AlphaGo's reply, he stared blankly at the board. Then he smiled, sat down, and started thinking. The longer he thought, the more serious his expression became, while the clock ran down little by little.] (;W[oi]C[After twelve minutes of thought, Lee finally pushed up at 38. Perhaps he was feeling the pressure, as the direction of this move is clearly problematic: White is helping Black build up the bottom. See the variation.] ;B[nj] (;W[mh]C[Even now, AlphaGo thought the knight's move at 40 was inappropriate, and recommended pushing as shown in the variation. It seems that Black 37 not only helped AlphaGo on the board, but also threw Lee off balance psychologically. At this point, AlphaGo’s win rate reached 55%.] ;B[gp]C[Black 41 further restricted White's potential on the left, while enlarging Black's in the center.] ;W[gq]C[At this point, Lee had 1 hour and 16 minutes, AlphaGo 1 hour and 34 minutes.] ;B[dn]C[This connection was a definite overplay for AlphaGo.] ;W[dm]C[After White pushed here, even AlphaGo's own win rate suffered a rare decline. Lee Sedol stared at the board with a scowl, evidently confused by AlphaGo's strategic slip. Drawing on the lessons of the first game, he remained cautious, taking time to verify each move.] ;B[fo] ;W[hp] ;B[ho] ;W[eo] ;B[en]C[When Black blocked at 49, AlphaGo's win rate fell to 50%. This may have been Lee's only chance to wrest control of the game. See the variation for one way he might have done so.] (;W[fn]C[Regrettably, Lee missed the crucial opportunity, and chose this atari instead.] ;B[em]C[When Black extended, AlphaGo's win rate shot up to 59%! ] ;W[el] ;B[fm] ;W[gn] ;B[fl] ;W[go] ;B[ek] ;W[dk] ;B[dl] ;W[cl] ;B[eh] ;W[di]LB[eh:A][di:B]C[Lee still looked unconcerned. Through 62, Black had gained nothing locally, while White had captured two stones at the bottom, and furthermore the center group was not yet safe. On the face of it, White should at least not have been worse off. Globally speaking, however, Black had reduced White's left side in sente, made the profitable exchange of A for B, and come away with sente to take the last big point at the top. Overall, it would be hard not to call this a strategic success for Black. Many of the professionals in the commentary room did not understand Black's way of playing, but after game 1, they were hesitant to pass judgment.] ;B[pj] (;W[qi]C[Lee spent a few minutes in thought, and patiently descended with 64. AlphaGo felt this move was too soft, as did Gu Li and Zhou Ruiyang, and would have chosen to come back to the center as shown in the variation.] ;B[rf] ;W[rg]C[At this point, Lee Sedol had 59 minutes, AlphaGo 1 hour and 21 minutes.] ;B[kd]C[When Black defended the upper side, AlphaGo pulled clearly into the lead.] (;W[hn]C[Lee followed with several more slow moves, perhaps still misled by White's apparent gains on the left. This was one such move - see the variation.] ;B[om] (;W[re]C[Taking a stone on the second line was even slower. This choice left a deep impression on Gu Li and Zhou Ruiyang, who felt that Lee must have thought White ahead to play like this. The variation shows a better option for White.] ;B[rd] ;W[sf] ;B[fi]C[For AlphaGo, the outlook was continually improving. When Black played 73, its win rate reached 64%. For a human player, Go requires the capacity to feel. The better the player, the more effectively their feelings steer them towards good moves and away from bad ones. However, if we rely too much on feeling, it begins to obscure rational calculation and judgment. After the AlphaGo match, Lee Sedol won nine consecutive games. When asked for his secret, he replied, "Do not rely on instinct. Calculate with the utmost precision." That may be the lesson he drew from this game.] ;W[gk]LB[fi:A]C[After Black protected at A, White's attack at 74 became much less severe.] ;B[hm]C[On seeing 75, Lee finally seemed to wake up.] ;W[in]C[He sighed, and made the necessary extension.] ;B[hl]C[By now Black's advantage was obvious.] ;W[ko] ;B[kp] (;W[gc]C[Seeking a comeback, Lee launched the do-or-die invasion at White 80! However, AlphaGo thinks White should remain patient, as shown in the variation. At this point, Lee Sedol had 50 minutes, AlphaGo 1 hour and 12 minutes.] ;B[df]C[Just as everyone was debating how Black should answer locally, AlphaGo played the shoulder hit at 81, reinforcing the center while subtly pressuring White's invading stone. It felt like a breath of fresh air - truly, an amazing example of whole-board thinking! Not only did this move connect up the center, it completed a huge wall. Although Black had done nothing to attack White directly, the invisible pressure was suffocating! The saying normally goes "attack is the best form of defence," but in this case, defence was the best form of attack.] ;W[id]C[Facing 81, Lee sobered up completely. He sighed, his face reddening. Because Black's center potential is so great, White can no longer be satisfied with living locally. The attachment aimed to escape.] ;B[jc]C[Drawing back was a calm response. At this point, Lee had 41 minutes remaining, AlphaGo 1 hour and 10 minutes.] ;W[ge] ;B[dg]C[Black 85 was solid defense.] ;W[cf] ;B[ch] ;W[bh] ;B[dh] ;W[bi]C[Up to here, Black had not only compressed White's territory on the left, but also reinforced the connection between the center and the corner.] ;B[hd]C[Following this hane, it became difficult for White to save the initial invasion stone.] ;W[he] ;B[gd] ;W[fd] ;B[hc] ;W[fe] ;B[ec] (;W[gh]C[White had no choice but to escape, since connecting would have meant the death of the whole group. See the variation.] ;B[fc]C[At this point, AlphaGo’s win rate reached 73%.] ;W[gi]C[After the cut, Lee had no real chance of winning. We have all had the experience of playing a game where we are behind. Against a person, the best hope is to stay calm and patiently await the opponent’s mistakes. After all, to err is human. Against AlphaGo, of course, this strategy is futile. It is calmer than you, more patient than you, and, by the time you realize you are in trouble, the game is already decided. Lee had just experienced this painful process, the desperation of knowing one's fate while being helpless to change it. But, as a professional Go player, he could only steel himself and press on.] ;B[ii] ;W[hk] ;B[ik] ;W[il] ;B[im] ;W[ij] ;B[jl] ;W[jj] ;B[if]C[Here, AlphaGo’s win rate reached 78%.] ;W[km] ;B[kl] ;W[lj] ;B[lk] ;W[lo] ;B[li]C[At this point, Lee had 10 minutes, AlphaGo 48 minutes.] ;W[kj] ;B[ci] ;W[cj] ;B[mj] ;W[nr] ;B[mr] ;W[lq] ;B[lp] ;W[mq] ;B[np] ;W[lr] ;B[lm] ;W[kh] ;B[hg] ;W[qc] ;B[qd] ;W[rc] ;B[pc] ;W[sd] ;B[gg] ;W[ce] ;B[bd] ;W[qb] ;B[hi] ;W[jg] ;B[hj]C[In the end, AlphaGo never went for the kill in the center, instead nibbling away at White's stones bit by bit. Although it looked as if White had destroyed much of Black's territory at the top and bottom, the actual score tilted ever more strongly in Black's favor.] ;W[ob] ;B[pb] ;W[pa] ;B[nb] ;W[de] ;B[ee] ;W[gj] ;B[hh] ;W[ej] ;B[nf] ;W[mf] ;B[me] ;W[rk] ;B[fh] ;W[el] ;B[nh] ;W[ng] ;B[lg]C[Even though the result was already decided, the beautiful tesuji at Black 159 is worth remembering! With this move, White's center collapsed.] ;W[lh] ;B[mg] ;W[og] ;B[kg] ;W[ni] ;B[jh] ;W[na] ;B[ki] ;W[mi] ;B[ji] ;W[nc] ;B[mb] ;W[od] ;B[mc] ;W[oc] ;B[kr] ;W[ms] ;B[io] ;W[ip] ;B[jo] ;W[jn] ;B[ir] ;W[hr] ;B[ql] ;W[rl] ;B[qm] ;W[rm] ;B[ao] ;W[bm] ;B[ln] ;W[kn] ;B[mo] ;W[be] ;B[ae] ;W[af] ;B[ad] ;W[ma] ;B[la] ;W[oa] ;B[dd] ;W[bg] ;B[lb] ;W[pn] ;B[on] ;W[er] ;B[cr] ;W[fp] ;B[iq] ;W[hq] ;B[qj] ;W[rj] ;B[ks]C[As the game neared its end, Lee continually recounted the score, looking for some sort of miracle. But he searched in vain: as the world had already realized, AlphaGo had won. After playing on doggedly in byo-yomi, Lee Sedol resigned at move 211. In that moment, I heard the reluctance in his voice, and saw the regret etched upon his face. During the press conference, Lee's voice was choked with emotion, and he repeated many times how impressed he was with AlphaGo's near-perfect play. The way he spoke, it seemed as if he bore the weight of the entire Go world on his shoulders. Although AlphaGo's play in the first two games had verged on perfection, the match was not yet over. Behind Lee's trembling voice there stood a firm conviction: "I may have lost the second game, but there is still a third game left to play." At the end of this game, the entire Go world was left astonished and bewildered. Perhaps the time had come to rethink our understanding of AlphaGo, and of ourselves.]) (;W[fc]C[If White connects...] ;B[if]C[...Black traps the whole group.] ;W[gg] ;B[hh] ;W[ie] ;B[jf]C[White is dead.])) (;W[no] ;B[np] ;W[dc] ;B[cc] ;W[ef]LB[cc:4][dc:3][ef:5][no:1][np:2]C[AlphaGo thinks White should exchange 1 and 3, then jump out into the center with 5 to disrupt Black's thickness. This way might have given White more opportunities to turn the game around.])) (;W[fj]C[Even now, White should attack the center. AlphaGo thinks this jump is critical.] ;B[hl] ;W[no] ;B[np] ;W[jn] ;B[jl] ;W[ln] ;B[ll] ;W[gc]LB[gc:9][fj:1][hl:2][jl:6][ll:8][jn:5][ln:7][no:3][np:4]C[Through 8, although Black connects, the center is clearly not as good as in the game. When White invades with 9, the position looks balanced, and both sides are in for a long battle.])) (;W[no]C[AlphaGo thinks that White should first attack the three black stones on the right, then break into the center.] ;B[mo] ;W[nn] ;B[np] ;W[om] ;B[lm] ;W[lj] ;B[nl] ;W[fj] ;B[hl] ;W[hn]C[This way, Black's center is much weaker. Both Gu Li and Zhou Ruiyang preferred this to the game.])) (;W[hn] ;B[qi]C[AlphaGo thinks White should come back to the center immediately, as this hane is nothing to be afraid of.] ;W[qh]LB[hn:A]C[Although Gu Li and Zhou Ruiyang were unsure about White A, they agreed that the hane is not very severe.])) (;W[fp]C[The atari is crude but effective.] ;B[fn] ;W[io] ;B[el]C[Black must escape with this tesuji...] ;W[hn] ;B[go] ;W[ip] ;B[jq] (;W[lq]LB[em:A]C[...but White takes sente to switch to the bottom. Note that White cannot use this move to cut at A, as shown in the variation.] ;B[lp] ;W[nr] ;B[gl]C[Black has no choice but to let White connect, and the result favors White.]) (;W[em]C[If White cuts...] ;B[fm] ;W[fl] ;B[gl] ;W[fk] ;B[gm] (;W[ek]C[White cannot omit this defense - see the variation.] ;B[im]LB[ek:7][fk:5][fl:3][gl:4][bm:A][em:1][fm:2][gm:6][im:8]C[After Black ataris and connects, White must capture at 7 to protect the cutting point at A. Black can now attach at 8, and White will be hard-pressed to handle the group at the bottom. ]) (;W[im]C[If White tries for the outside...] ;B[bm]C[...this cut sets up a fatal tombstone squeeze.] ;W[bl] ;B[am] ;W[al] ;B[cl] ;W[an] ;B[bm] ;W[am] ;B[dl] ;W[bm] ;B[bk]C[White is dead.])))) (;W[ni]C[Since White has already chosen to push, AlphaGo believes White should push again, then take the 3-3 point.] ;B[mj] ;W[qc] ;B[re] ;W[oc] ;B[od] ;W[nb]C[Notably, AlphaGo prefers the kosumi at White 8 to crawling as shown in a previous variation. Perhaps, because Black is not as developed on the upper side, the corner profit is relatively more important here.])) (;W[pj]C[AlphaGo believes White should push along the fourth line.] ;B[ol]C[Black will answer with the jump, and White is free to invade the upper side.] ;W[lc] ;B[mb] ;W[fd]C[Shi Yue suggested this variation as well, and it now appears to be the professional consensus on how White should have replied.])) (;B[eh]C[Black was originally planning this jump, a move that has appeared in a number of professional games lately.] ;W[qc]C[White enters at the 3-3 point and lives in the corner.] ;B[re] ;W[oc] ;B[od] ;W[nc] ;B[pc] ;W[pb] ;B[mc] ;W[mb] ;B[lb] ;W[rb] ;B[nb] ;W[ob] ;B[ma]C[This is an interesting strategy, and Gu Li mentioned that many top players have also chosen to play this way. Through here, the result is equal.])) (;B[nd]C[If Black jumps directly, White will take the 3-3 point straightaway.] ;W[qc] ;B[qd] ;W[rd] ;B[pc]C[As the right side is uninteresting, Black has no choice but to protect the top.] ;W[rb] ;B[qb] ;W[rc]C[This outcome is clearly inferior to the game.])) (;W[ed]C[AlphaGo thinks the upper side is more valuable, so White should approach directly.] ;B[cf]C[Black will extend on the third line.] ;W[cc] ;B[bc] ;W[dc] ;B[bb] ;W[gc] ;B[ie] ;W[nc] ;B[oc] ;W[nd] ;B[pf] ;W[kc] ;B[hc] ;W[gd] ;B[ke] ;W[lf]LB[bb:6][bc:4][cc:3][dc:5][gc:7][hc:14][kc:13][nc:9][oc:10][ed:1][gd:15][nd:11][ie:8][ke:16][cf:2][lf:17][pf:12]C[Through 17, a fight develops. Gu Li and Zhou Ruiyang disagreed with Black 8, suggesting that Black defend directly at 9, since it is hard to see the practical value of the jump at 8. Nonetheless, they found AlphaGo's suggestion for the direction of play quite interesting.])) (;W[do]C[AlphaGo thinks White should connect on the outside, earning sente to come back and attack the four black stones on the bottom.] ;B[bo] ;W[cr] ;B[cl] ;W[kp] ;B[nm] ;W[lq] ;B[mr] ;W[kn] ;B[pm] ;W[ql] ;B[dn] ;W[ck] ;B[dl] ;W[cg] ;B[ed] ;W[nc] ;B[oc] ;W[nd] ;B[qf] ;W[kc]C[This would be a balanced game. Gu Li and Zhou Ruiyang thought that while this variation merits consideration, there is nothing wrong with the real game.])) (;W[jp]C[As Black did not finish the joseki at the bottom, White naturally has the option to pincer.] ;B[dj]C[AlphaGo suggests Black would tenuki once more to build up the right.] ;W[ed] ;B[df] ;W[cc] ;B[bc] ;W[dc] ;B[bb] ;W[gc] ;B[ff] ;W[ge] ;B[fe] ;W[fd] ;B[hd] ;W[ib] ;B[jb] ;W[hb] ;B[kc] ;W[jd] ;B[jc] ;W[gd] ;B[qf]C[This sequence would lead to a balanced game. This way would have been more keeping with Lee's style, but perhaps Lee adopted a more defensive stance as a probe to sound out AlphaGo's strategy.])) (;W[ed] ;B[hd] ;W[dg] ;B[ee] ;W[fe] ;B[ef] ;W[cc] ;B[cf] ;W[bd] ;B[fd] ;W[ec] ;B[be] ;W[dd] ;B[ce] ;W[gd] ;B[he] ;W[cl] ;B[qo] ;W[ro] ;B[pp] ;W[qq] ;B[qn] ;W[rn] ;B[qm] ;W[qf] ;B[nd] ;W[rd] ;B[qc] ;W[qi] ;B[cp] ;W[cq] ;B[bq] ;W[co] ;B[bp] ;W[do] ;B[bo] ;W[cr] ;B[dn] ;W[bm] ;B[bn] ;W[ci] ;B[hq] ;W[fo] ;B[fn] ;W[go]C[AlphaGo anticipated something along the lines of this sequence. Of course, this is only one of many possibilities, but we can clearly see that AlphaGo plays some well-known joseki, meaning that it agrees with at least some of modern joseki theory.]))