(;GM[1]FF[4]SZ[19]AP[SmartGo:3.1.4]CA[shift_jis]
GN[selfplay23_annotated]
PW[AlphaGo]
PB[AlphaGo]
EV[AlphaGo selfplay]RO[23]
KM[7.5]
RE[W+R]
RU[Chinese]MU[1]
(;B[pd]
C[The variation shows the first 30 moves of a game between Honinbo Shusaku (White), and Sekiyama Sendayu, played in 1851. I added the var because Sekiyama played a move that was very similar in meaning to move 28 of this game. ]
;W[dd];B[pp];W[dq];B[co];W[qc];B[qd];W[pc];B[nc];W[oc];B[od];W[nb]
(;B[cc]
C[Black invades at the 3-3, a favorite move for AG. While it has become normal to play away from the UR corner at this point in the sequence, I will suggest that Black could have continued in a more conventional fashion by finishing the joseki (see var). ]
;W[cd];B[dc];W[ec];B[eb];W[fb];B[fc];W[ed];B[gb];W[db];B[fa];W[cb]
C[White's choice of joseki in the UL corner makes sense, as Black's ponnuki is not well placed. The shape with White playing a hane at A reduces the value of the upper side. ]
LB[nb:A];B[gq]
C[Since Black has potential to build a moyo on the right half of the board, It makes sense for Black to play a pincer like this. While pressing with Black A is well know to be a favorite move for Go playing programs, that move does not work well in this board position. ]
LB[ep:A];W[ep];B[go];W[gn]
C[White's attachment must come as a suprise when seen for the first time, but this move is actually a known tesuji. White is making use of the forcing move at A, without putting that stone on the board. In a var for the 1st move of this game I show an ancient game with a similar shape. ]
LB[dn:A]
(;B[ho]
C[The var shows White's plan if Black extends in the other direction. ];W[fn]
;B[dm];W[hn];B[jo];W[in];B[io]
(;W[km];B[dj];W[lo];B[lq]
(;W[qq];B[pq];W[qp];B[po];W[qo];B[qn];W[rn];B[qr];W[rr];B[ro]
C[Black cutting here on the second line has become after the hane at A has become a mainline joseki now. Black's main idea is to prevent White from crawling into the right side by creating a wall down to the second line. ]
LB[qr:A]
(;W[rp]
C[White goes for the offered stone, a joseki variation that was originally considered slightly unsatisfying for White, but is now being played in various board positions. The alternative for White was to cut on the lower side (see var), but in this position the lower side has a low value, so the game move makes sense. ]
;B[rm];W[mc];B[nd];W[rc]LB[mc:A][rc:B]
C[Playing an atari at A and then sagari at B is the normal way for White to proceed when Black has played away in this UR corner joseki. White B gets rid of the weaknesses that might have been caused by a Black hane at the same point, and now White has a strong corner, with potential to attack the Black wall later. ]
;B[bc];W[bb];B[lm];W[kn];B[sn]LB[lm:A][kn:B][sn:C][lo:D]
C[The order of playing Black A first, waiting for White to protect at B, and only then taking at C is very precise. The A-B exchange gives Black extra potential in the center and right, but reduces the value of the lower side by allowing White to make a secure connection to D, and in itself this is an even trade. Black C increases Black's potential on the right at the cost of damaging the lower side, but after the A-B exchange that is a relatively minor loss. The AB exchange optimizes the value of Black C. ]
;W[pr];B[or];W[qs];B[lk]
C[Black jumps in the center, the natural follow-up after Black A. Black has ideas of attacking the big White group by sliding at B or pushing through at C. ]
LB[lm:A][bq:B][fo:C]
(;W[cp]
C[White creates a living shape in the corner, settling the potentially weak group. White could have invaded the right side with this move (see var), but then Black would have options to attack White on the left. ]
;B[qg]
C[The right side is so wide that Black really needs a stone on the third line to create a moyo structure, so it plays at A. ]
LB[qg:A];W[om]LB[nn:A][pn:B]
C[White plays an annoying peep, looking at the connection at A, and naturally, the cut at B. ]
;B[nn];W[nm];B[mn];W[pn];B[kl]LB[ll:A][fo:B]
C[Black secures a connected shape, preventing the White play at A, and Black is staring to look at the cutting attack at B. ]
(;W[pj]
C[White plays lightly with a plan to reduce Black's territory in the general area, instead of trying to attack Black's ponnuki directly (see var). ]
;B[il]LB[fo:A];W[do]
C[White connects the corner to the stones at A. ]LB[fn:A];B[ql];W[nj]LB[ok:A][ml:B]
C[Compared to the safer connection at A, White 76 makes a light shape and gives White potential to escape out into the center. White seems to be ready to refute the Black peep at A with a forcing move at B, but we will see how that turns out. ]
;B[ok]
C[Black peeps anyway.]
(;W[ml]
C[White peeps to create two threats. Simply covering at the left of Black's peep would have been bad (see var). ]
(;B[nk]
C[Black pushes through to force a trade. Connecting on the left is bad (see var). ]
;W[mk];B[mj];W[pk];B[pl];W[ll];B[lj];W[mm]
C[White has captured Black's stone at A. ]LB[lm:A]
(;B[ol]
C[Black could not have saved the cutting stone (see var). ];W[ln];B[le];W[nq]
LB[le:A][nq:B][om:C]
C[Black enlarges the right side moyo with A, and White will get compensation by gaining territory with B. The whole fight starting with White C seems to have ended with an even trade. ]
;B[nr];W[mq];B[mr];W[kq];B[kp];W[lp];B[lr];W[oq]LB[jn:A][kq:B]
C[White's territorial gain here was big, and there is added value in the fact that White need not worry about the cut at A now. There is also a big endgame move that White has created on the lower side, which involves the aji with White's stone at B. Can the reader find the endgame tactic that AG played?]
;B[fd]
(;W[hr]
C[White's endgame play on the lower side was this move on the second line. Just to show that White was losing the immediate semeai, I have added two vars. ]
(;B[jq]
C[Black must play defensively to win the semeai. The var shows how White can win if Black plays from outside. ]
;W[re];B[rd];W[sd];B[qe]
(;W[jr]
C[This probe move will change the size of the next move in this area, depending on how Black reacts (see var). ]
(;B[iq]
C[When Black answers this way, the size of the next local move has been reduced, and White is free to play in the center. See var for the other way Black might answer. ]
;W[ii];B[pm];W[on];B[ig];W[gi];B[cn];W[ch];B[ci];W[dh];B[er]LB[jr:A][iq:B][kr:C][os:D]
C[Black gets to play the big point on the lower side, but now White's probe has gained a few points, showing that it was perfectly timed to give White profit however Black replied. The A-B exchange will enable White to connect later at C and get a squeeze with D in the endgame. ]
(;W[bk]
C[The normal looking 3rd line invasion is not successful in this case (see var), so White invades on the second line. ]
(;B[ck];W[bi];B[bj];W[aj];B[cj];W[bg];B[bl];W[rf];B[rg];W[jg];B[ee];W[df]
;B[if];W[kh]
(;B[lc]
C[White might seem to have a strange shape in the center, but Black cannot cut it (see var). ]
;W[mb];B[mh];W[dr];B[fq];W[kc];B[ld];W[lb];B[de];W[ce];B[ef];W[mg]
(;B[cf];W[bd];B[dg];W[lg]
C[This move starts a trade in which White offers up the left side and destroys Black's right side territory. It is already clear that the game will be very close, and both sides are trying to get in one more forcing exchange to tip the game in their favor. All of the threats are about equal in size, and backing off will cost a few valuable points. For example, If Black were to answer at A now, White would gain a few points before protecting at B. ]
LB[ng:A][bf:B];B[bf]
C[Black 149 reduces White's side by about 7 pts, and threatens to capture the marked White group. ]
TR[ch:dh];W[pg]
C[White does not have time to try saving the left side with A, but instead reduces Black's right side with this strong attachment. Note that cutting points such as B or C will become an issue if Black is not careful. ]
LB[ei:A][qf:B][je:C];B[ph];W[oh];B[ih];W[ji]
(;B[oj]
C[Black pushes through to capture the marked cutting stone with the least possible damage to the right side. A more greedy move leads to collapse (see var). ]
TR[nj]
(;W[pi]
C[White cannot get a good result by saving the cutting stone (see var), and White 156 is correct. ]
;B[qh];W[oi];B[ni];W[nf]LB[md:A][je:B][ri:C]
C[White makes a connection with 160, and also threatens Black. If White A next, there is a double threat of B or C. ]
;B[je];W[jl]TR[ji]
C[After White 162, White will be able to connect in the center or make eyes for the marked group. ]
;B[fi]
C[This might be called the beginning of the endgame. Black temporarily abandons the attack on White's group in the center, and takes profit on the left. ]
;W[gh];B[fh];W[gg];B[og]
C[Black's cut at 167 has to do with eyes for both Black and White.]
(;W[nh]TR[pg]
C[White could have extended from the marked stone to connect with sente, but that would lose territory and eyespace (see var). ]
;B[ki]
C[Black 169 was a well-timed forcing move that prepared to cover at A. ]
LB[jk:A];W[jh];B[jk];W[kk];B[jj]LB[ik:A][ij:B]
C[At this time White can't cut at A because Black can push through at B and cut White off in the center. ]
;W[gj];B[of];W[lh];B[fg];W[mi];B[nj];W[ge];B[jc];W[jb];B[kd];W[kb];B[ic]
;W[hd];B[hk];W[fj];B[fl];W[md]LB[hc:A][id:B][fe:C]
C[After 190 White threatens to push twice at A, forcing Black to connect on the first line, and after forcing again with B White can cut at C to capture the Black group.]
;B[fe];W[rk]TR[pl]
C[With the potential connection at A, White now has time to grab some points with 192 while putting pressure on the marked Black group. ]
LB[me:A];B[ri];W[rj];B[me];W[li]
C[With 196, we can see that White is finally preparing to make eyes. ];B[kj]
;W[gl];B[gk]LB[gl:A][gk:B][el:C]TR[nj:nk][ok]
C[The exchange of White A for Black B has to do with the fact that the marked Black group is not yet alive, and set up an endgame sequence with White C that will come later in the game. ]
;W[ng];B[qf];W[kf]
C[White is alive. ];B[se];W[sc];B[bp];W[bq];B[ao]LB[bp:A][ao:B]
C[Black A and B was the biggest endgame move. ];W[el]
C[White 208 threatens the Black group, reducing Black's territory on the left, and Black will need to protect at A soon. ]
LB[rl:A];B[em];W[ej];B[ei];W[fm];B[fk];W[ek];B[rl];W[aq];B[gf]
C[Black starts a final ko to get territory in the center. ];W[hf];B[hg];W[ff]
;B[cr];W[cs]LB[cr:A][cs:B][ds:C][en:D]
C[Exchanging Black A for B loses a couple of points when compared to a Black hane at C, but Black needs the extra ko threats. There is some compensation in that White has only one secure eye in the corner and that will change how White can react to Black D later. ]
;B[gf];W[ij];B[ik];W[ff];B[ae];W[ac];B[gf];W[sp];B[so];W[ff];B[br];W[bs]
;B[gf];W[kr];B[ir];W[ff];B[hj];W[hi];B[gf];W[ko];B[jp];W[ff];B[mp];W[oo]
;B[gf];W[cl]
C[White has run out of ko threats, and 248 is the biggest threat now. ];B[he]
;W[dl];B[ak];W[ap];B[bo];W[bm];B[cm];W[am]LB[ap:A][bo:B]
C[Itwas accurate to exchange White A for Black B first. White creates a seki to reduce Black's left side. ]
;B[ai];W[sf];B[es];W[ds];B[en];W[fo];B[eo];W[fp];B[ib];W[os];B[ns];W[ps]
;B[rs]
C[Black throws away a ko threat, as if it likes to do that to annoy me. I guess it already knew that White would have enough ko threats to win the final ko in any case. ]
;W[op];B[ks];W[dp];B[al];W[dn];B[ne];W[gp];B[hp];W[ah];B[di];W[be];B[af]
;W[eq];B[gr];W[im];B[hl];W[ia];B[ha];W[ja];B[da];W[ca];B[ea];W[si];B[sh]
;W[sj];B[qi]
(;W[sl]
C[)Black resigned. Assuming the sequence from Black A to White D, White will win the final ko. White wins by 1/4 stones, or half a point in the Japanese counting system.]
LB[kl:A][jm:B][gm:C][hm:D])
(;W[se];B[sg];W[sl];B[kl];W[jm];B[gm];W[hm];B[jf];W[lf];B[gl];W[sk];B[sm]
;W[kk];B[ke];W[kl]
C[W+0.25 stones (0.5pts)]))
(;W[pf];B[qf];W[rj];B[nh];W[ng];B[qj];W[qk];B[rk];W[qi];B[ri];W[of];B[sj]
LB[pf:A][rj:B][nh:C]
C[When White extends at A to connect with sente, the effectiveness of White's invasion at B is reduced. Black can squeeze from C to connect on the right side, reinforcing the local Black groups. White has no eyes and must add a stone to connect in the center. ]
))
(;W[ni];B[nh];W[oi];B[ng];W[og];B[nf];W[qf];B[lh];W[pf];B[hj];W[hi];B[jk]
C[If White pulls out the cutting stone at A, this is the only sequence with which White can escape. After Black B, White's center group is about to die, so this is a failure for White. ]
LB[ni:A][jk:B]))
(;B[oi];W[pi];B[qh];W[ni];B[oj];W[nh]LB[oi:A][nj:B]TR[lj]
C[If Black plays A to capture White on the right, White can save the cutting stone at B with this sequence. Now the marked Black group will die, and this is bad for Black. ]
))
(;B[lg];W[lh];B[mi];W[lf];B[ji];W[ih];B[jh];W[jf];B[ie];W[je];B[jd];W[me]
;B[md];W[ke];B[ng];W[kg];B[jj];W[nf];B[og];W[gf]))
(;B[ji];W[ih];B[jh];W[jj];B[ki];W[li];B[kj];W[mi];B[kk];W[jl]
C[If Black tries to cut at A, this ends in disaster for Black when Black runs out of liberties. ]
LB[ji:A]))
(;B[bj];W[dk];B[ek];W[ck]LB[cj:A][el:B][bm:C]
C[With the weak points at A and B, and White C to extend White's liberties, this fight is bad for Black. ]
))
(;W[ck];B[bj];W[dk];B[bk];W[ek];B[bh];W[bg];B[bf]LB[ck:A][bj:B][bf:C][bd:D]
C[White A is met by Black B, and White does not have much of an attack. Black's troublesome attachment at C sets up a threat at at D, ]
))
(;B[kr];W[gr];B[ee];W[bd];B[lc];W[mb];B[kb];W[iq];B[ip];W[hq];B[ko];W[ij]
LB[jr:A][iq:B][gr:C]
C[Compared with the var in which White A was answered by Black B, White has gained almost 2 pts in this var. In this case it was big enough for White to play the move at C. ]
))
(;W[gr];B[lc];W[mb];B[ee];W[bd];B[cf];W[jr];B[iq];W[ir];B[kr]LB[gr:A][jr:B][er:C]
C[If White starts with connecting underneath at A, Black will play away. This var shows how Black will defend the lower side when White then plays at B. The difference in territory between White A and a Black play at C was 23 points. ]
))
(;B[gr];W[kr];B[ir];W[iq];B[hq];W[jq];B[ip];W[ls];B[jp];W[os];B[jr];W[ks]
C[Black loses by one move. ]))
(;W[jq];B[iq];W[ir];B[hr];W[kr];B[ls];W[ks];B[js]
C[Black wins by one move. ])
(;W[kr];B[jq];W[jr];B[iq]
C[Black wins by one move. ]))
(;B[ln];W[on];B[no];W[np];B[oo];W[oq]
C[White captures Black. ]))
(;B[ll];W[pk]LB[ok:A]
C[White captures the Black stone at A to make an eye. White will have no trouble living with this group and this is bad for Black. ]
))
(;W[nk];B[ol];W[nl];B[qk]
C[When White covers at A, White ends with and eyeless shape. This is bad for White. ]
LB[nk:A]))
(;W[qm];B[ql];W[rn];B[il];W[so];B[fo]
C[Winning the ko was not good enough for White, when Black still has some potential territory on the right and a strong attack in the center. ]
))
(;W[ph];B[nh];W[pj];B[fo];W[cp];B[bo];W[bp];B[ik]LB[ph:A][fo:B][ik:C]
C[White A is a big move that will take away most of Black's potential on the right. Pushing to cut with B is an example of how Black might attack on the left, with the follow-up at C after White lives in the corner. ]
))
(;W[pr];B[rq];W[qs];B[rp];W[qr];B[rm];W[pn];B[qm];W[mq];B[mr];W[nq];B[on]
LB[pr:A][rq:B]
C[This sequence, with White cutting at A and Black then squeezing with B, is a modern joseki. In this case, Black's wall is pointing in the right direction (right side) and this favors Black. ]
))
(;W[mc];B[nd];W[rc]))
(;W[ck];B[el];W[km];B[dj];W[ci]))
(;B[fo];W[dn];B[cn];W[dm];B[cl];W[fn];B[ho];W[cp]LB[fo:A][dn:B][fn:C]
C[If Black extends at A, White can then press at B before covering at C. The exchange of A for C becomes bad for Black, and this is good for White. ]
))
(;B[mc];W[mb];B[lc];W[qk];B[cf];W[fc];B[fp]LB[qk:A][fp:B]
C[The joseki in the UR corner ends with White getting a tempo to split the side at A, which gives White room to make a two space extension on either side. Black will continue on the left side of the board, and Black's final move at B will work well with Black's advantage in the centrer. ]
))
(;B[eq];W[op];B[qp];W[qq];B[rq];W[pq];B[ro];W[kq];B[dc];W[cp];B[pc];W[qe]
;B[cf];W[qn];B[po];W[pm];B[oo];W[nm];B[mm]LB[mm:A][no:B][mo:C]
C[Black A is a tesuji that makes use of potential forcing moves such as Black B or C, without actually putting them on the board. Black will force White to back off a bit, giving Black some room to make shape. This became the standard move for this particular joseki, and can still be seen in modern games. ]
;W[nl];B[nn];W[np];B[ln];W[nd];B[ql];W[pl];B[nc];W[od];B[oc];W[md]LB[mm:A]
C[This is an early example of Black's tesuji at A, and is also a game in which Honinbo Shusaku shows his solid style even when playing White with no komi. In 1851 Shusaku was already the heir of the Honinbo house, and was considered second only to Honinbo Shuwa. ]
))

