(;GM[1]FF[4]SZ[19]AP[SmartGo:3.1.2]CA[UTF-8]
GN[008_Zero_Master]
PW[AlphaGo Master]
PB[AlphaGo Zero]
KM[7.5]
RE[B+R]ZT[60];B[pp];W[dp];B[pd];W[dd];B[fq];W[cn]LB[dr:A][fc:B][mq:C][pj:D]
C[There are several moves that a human player might think of playing for Black in this position. Sliding at A or playing an extension on the lower side are the local joseki moves, and would work in this board position. Black B, C, or D are other moves that I think of as feasible. Zero has only one move for this position, none of the above. ]
;B[cc];W[cd];B[dc];W[ec];B[eb];W[fc];B[fb];W[gc];B[gb];W[hc];B[nq]LB[nq:A][dm:B][di:C]
C[Zero plays at A every time, but when humans pros play this opening, I often see Black playing a shoulder hit at B or the invasion at C. When White has a wall in the upper left, the left side is an important area. ]
;W[qf]LB[qf:A][di:B][qj:C]
C[White A ends the sequence that repeats every time Zero has Black in this set of games. With this move, White B or C are other moves that look feasible. ]
;B[qj]LB[pi:A][qi:B]
C[In this position, Zero could play this pincer, or a pincer at A or B. This is a position with which I feel confident that most human pros would agree with these choices. The upper side looks relatively small, and it seems natural for Black to play a pincer on the right side. ]
;W[nd];B[ne];W[oe]
C[With the hane at A,  Master initiates a sequence that was previously almost non-existent in human play but was played in 8/10 games in this set. The viewer must be warned that while White A works well with this particular board position, in most cases it would be a bad move.  ]
LB[oe:A];B[od];W[of];B[md];W[nc];B[mc];W[ob]LB[ob:A][oc:B]
C[In my analysis of game 2 from this series, I looked into a variation with White playing at B instead of A. In this commentary, I will just say that White turning at B is bad shape, and that it leads to a bad result for White. White A is a tesuji that sets up the squeeze that follows in the game sequence. ]
;B[mb];W[qd];B[pc];W[qc];B[pb];W[qb]LB[qb:A][qj:B]
C[White's final move at A secures a base for the White group. Master played this move in all 5 games in which Zero had played the low pincer at B. To judge this local result, I would say that in most early opening board positions, Black's wall would have a higher value than White's corner territory, and this local result would give Black an advantage. However, in this game, the open part of the upper side is a very narrow, and the only way Black can make good use of this wall in the upper right is to attack White's marked group. With this board position, White can be satisfied. ]
TR[gc:hc];B[dq]TR[md]LB[dq:A][dh:B][ee:C]
C[Looking at Black A, I think that Zero has a strong bias towards grabbing territory. If I was playing with Black, I would want to use the marked wall in an attack against White's group in the upper left. I suggest that Black should invade at B, looking to peep at C next and attack White's wall. ]
;W[cq];B[cr];W[eq];B[dr];W[ep];B[er];W[ro]LB[bq:A][di:B][go:C][fp:D]
C[The joseki move in the LL corner was White A. In this position White has potential to build a moyo on the left, and after White plays a stone at B, White will naturally want to expand into the center next, starting with a play at C or D. So, the joseki move at A is not always urgent, and in this case ommitting it gives White some extra flexibility to expand into the center. ]
(;B[qo]
C[Black played from above to avoid a fight on the right side (see var). ]
;W[rp];B[qm];W[pq];B[oq];W[pr];B[rn]LB[rn:A][fp:B]
C[The lower right sequence is a joseki that has been common in human games, even before AlphaGo. Zero plays very solidly with A making a thick shape and seeming to completely ignore White's potential moyo on the left. Black A creates some aji in the corner that Black will make use of later in the game. That said, I would have been tempted to play at B and expand Black's lower side area. ]
;W[fp]LB[fp:A]
C[White has a potential moyo on the left, and Black has an area on the lower side that could expand into the center. White needs to play an extension on the lefdt side, but forces once with A to get some extra space in the center. ]
;B[gq];W[di]
C[With Black, I would want to play at A now. ]LB[ho:A];B[gp]LB[gp:A][ho:B]
C[Black A is a slow move, compared to the more flexible keima at B. Zero likes to allow the opponent to build a big moyo, and is very good at invading. ]
;W[bd];B[bc]
(;W[hn]TR[hn]
C[White's marked move places an emphasis on reducing Black's lower side, but has a weak connection to the left, which will make it difficult for White to continue by expanding the left side moyo. I say White should have played one line to the left (see var). ]
;B[go]TR[hn]
C[Extending towards the center, Zero plays another slow and solid move. I agree with it this time, as it is difficult for White to make a good connection from the marked stone to the left side, and White is starting to look thin. ]
(;W[dk]TR[hn]
C[Master's idea here seems to be to surround the left side on the 4th line and use the marked stone to reduce Black's potential in the center. This seems to be a thin way to play, and White's game plan is becoming difficult to implement. I suggest that White should have made a loose connection with a keima in the center (see var). ]
;B[em]LB[dk:A]
C[Since White has surrounded the left side with A, it is a good time for Black to play this kikashi from above. ]
(;W[hl]
C[White now jumps in the center, seeming to invite Black into White's territory. This seems to be a change in plan, as it would be more consistent for White to continue surrounding the left side (see var). ]
(;B[fh]TR[em]
C[Instead of immediately moving in from the marked stone, Zero shows it's skill in handling a fight in the opponent's area. The direct approach is dangerous for Black (see var). ]
(;W[hg]
C[White tries to attack on a large scale. Answering on the left with this move was not an attractive choice for White (see var). ]
;B[cm];W[dn]
(;B[dh]TR[cm][em]
C[Zero shows great flexibility in handling this difficult fight. Master is ready for Black to try to use the marked stones directly (see var), but Zero is not going to fall into that trap. ]
;W[ch];B[cg];W[dg];B[eh];W[cj];B[df]
(;W[bg]
C[It is correct for White to sacrifice the one stone (see var). ];B[eg];W[bf]
;B[hh]
(;W[gh]
C[White's wedge was unexpected (see var).  ];B[gg];W[gi];B[gf];W[hf];B[he]
;W[ie];B[ge];W[id];B[ee]
C[The Black group is now alive. The game still looks close. ];W[kn];B[jm]
LB[if:A][ed:B][cm:C]
C[Black attacks White in the center. With cutting points at A and B, and aji on the left with Black's stone at C, White is thin in the central area. ]
;W[km];B[jk];W[jg];B[gj];W[hi];B[kl];W[jn];B[im];W[in];B[dm]LB[gn:A]
C[Zero was setting this up with the moves in the center. At the very least, Black can count on a forcing move at A, so White cannot cut the marked Black stones off. Now White must make life in the LL corner. ]
TR[cm:em]
(;W[bp]
C[Locally it is better for White to play the hanetsugi first (see var). ]
;B[en]
(;W[br]
C[White must play at A to get an unconditional life in the corner (see var). ]
LB[br:A];B[hm];W[gm];B[gn]TR[km:kn][hn:jn]
C[Black cuts White off to attack the marked group. ];W[ik];B[bn];W[bo];B[jl]
;W[kq];B[ml];W[mm];B[nm];W[iq];B[jr];W[mr];B[bl];W[qp];B[po];W[an];B[rr]
C[White will not have time to save both the corner and the lower side group. ]
;W[ir];B[or];W[ps];B[qq]
C[White sacrifices the corner to make a life on the side. With this exchange, Zero has established a lead in territory. ]
;W[fm];B[fk];W[el];B[bm];W[bs];B[co]
(;W[ij]TR[fn]
C[Black cuts, and if White answers, White will no longer be able to cut at the marked point (see var). ]
;B[do];W[cp];B[fn];W[nn];B[nl];W[mq];B[os];W[fs];B[bk]LB[dl:A][am:B]
C[Black A and B are miai to make a second eye for the Black group. ];W[pj]
;B[qi];W[pk];B[qk];W[kj];B[mj];W[ll];B[lk];W[lm];B[kk];W[om];B[on];W[qr]
;B[rq];W[gl];B[am];W[ac];B[ab];W[cb]
C[Master apparently realizes that it is losing now, and will play what I call meaningless moves in the UL corner. In response, Zero will find an unnecessarily exciting way to win. ]
LB[cb:A];B[bb];W[db]
C[Black could even play away with no damage to the corner. ];B[da];W[ea]
;B[fa];W[ca];B[bh];W[bi];B[cf];W[ah];B[ej]
(;W[ea]TR[bi]
C[By forcing White to play the marked stone, Black has actually put the Black group in danger (see var). ]
;B[nb];W[hb];B[da];W[oo];B[pn];W[ea];B[pe];W[ga]
C[The UL corner Black group started out being unconditionally alive, so there was no necessity for Black to kill it. Zero is winning anyway, so I guess it doesn't care. The following endgame is also a bit bumpy, but Black has a safe lead throughout. My commentary ends here. ]
;B[pf];W[rg];B[qg];W[re];B[rh];W[mh];B[oi];W[oh];B[ph];W[np];B[ip];W[jp]
;B[pa];W[qa];B[nh];W[mg];B[nf];W[ni];B[nj];W[ng];B[og];W[li];B[op];W[no]
;B[sg];W[rf];B[kc];W[jc];B[sf];W[se];B[sh];W[oj];B[pi];W[hr];B[gr];W[gs]
;B[fr];W[kb];B[lb];W[kd];B[ld];W[ke];B[jb];W[lc];B[mp];W[lp];B[kc];W[ka]
;B[la];W[lc];B[ao];W[aq];B[kc];W[of];B[oe];W[lc];B[an];W[ap];B[kc];W[ol]
;B[es];W[lc];B[qe];W[sc];B[kc];W[lj];B[pl];W[lc];B[rd];W[sd];B[kc];W[fi]
;B[ei];W[lc];B[sb];W[rc];B[kc];W[fj];B[ek];W[lc];B[if];W[ih];B[kc];W[mk]
;B[nk];W[lc];B[mn];W[mo];B[kc];W[ra];B[ja];W[jj];B[mk];W[hp];B[lf];W[il]
;B[ms];W[ls];B[ns];W[is];B[dj];W[ci];B[ck];W[fl];B[dl];W[mi];B[ok];W[pk]
;B[oj];W[fd];B[fe];W[gk];B[cs];W[eo];B[kr];W[js];B[lr];W[ks];B[hq];W[dn]
;B[cn];W[kb];B[ho];W[lc];B[hs];W[jq];B[kc])
(;W[ak];B[ck];W[dl];B[dj];W[fl];B[bj];W[aj];B[ci]LB[ao:A][hr:B]
C[This will be a ko for the life of Black's group. Black has several local ko threats at A and B, so Black should be able to win this ko. ]
))
(;W[do];B[hr];W[is];B[fl];W[gl];B[ej];W[ck];B[ek];W[dl];B[fs]LB[do:A][hr:B][fs:C]
C[If White connects at A, Black can live with B and C. ]))
(;W[hm];B[bn];W[bo];B[bm];W[br];B[bs];W[aq];B[do];W[co];B[eo];W[ao]
C[Black still can make a ko with A. This is painful for White. ]LB[ar:A]
))
(;W[bm];B[bl];W[bn];B[cp];W[cl];B[hm];W[gn];B[gm];W[fn];B[ih];W[hj];B[jh]
TR[cm:em]LB[bm:A][cp:B][ih:C]
C[While is is easier for White to live by playing the hanetsugi at A, Black will take the opportunity to cut at B and reduce the value of the marked stones. As Black moves saves the cutting stone with C, we see black starting to attack in the center. ]
))
(;W[ih];B[hi];W[ii];B[ij];W[hj];B[ig]LB[ih:A]
C[It seems the natural move for White to play at A. This fight in the center is dangerous for both sides. ]
))
(;W[eg];B[hh];W[ef];B[ig]LB[eg:A][hh:B]
C[If White saves one stone with A, Black can make sabaki with the attachment at B. ]
))
(;B[dm];W[fn];B[ek];W[ej];B[fk];W[gi]TR[hg][fh]
C[In this variation the marked exchange has become bad for Black. ]))
(;W[eg];B[cm];W[dn];B[dm];W[fn];B[ek];W[ej];B[fk]TR[eg][fh]
C[Having played the marked exchange before this fight makes a big difference in helping Black escape. This Black group is not in danger. ]
))
(;B[cm];W[dn];B[dm];W[fn]
C[If Black jumps in at A, White will cut Black off to attack. ]LB[cm:A]))
(;W[dm];B[ej];W[dj];B[hl]LB[dm:A][hl:B]
C[If White answers with A, Black will attack White in the center with B. Black has the initiative in this fight. ]
))
(;W[fm];B[ee];W[ed];B[fh]LB[fm:A][gn:B][fh:C]
C[I suggest that White should play the keima at A. Black can cut from B, but that is not big enough to play immediately. Black will probably continue by reducing the left side with a play at C, unless Zero finds a more dramatic way to invade White's side area. ]
))
(;W[gn];B[ek];W[dk];B[dl];W[el];B[fk];W[dj];B[gm];W[em];B[hn];W[hm]LB[gn:A][ek:B][hm:C]
C[White should cap at A to expand the left side moyo. This diagram is an example of what might happen if Black floats in at B. White's final cut at C will cause trouble for Black in the center, and this is good for White. ]
))
(;B[rp];W[qo];B[qp];W[ql]LB[mg:A]TR[qo:rp]
C[In this variation, the marked exchange is a gain for White. White has various forcing moves in the vicinity of A, and will have an advantage in this fight on the right. ]
))

