(;GM[1]FF[4]CA[UTF-8]AP[CGoban:3]ST[2]
RU[Chinese]SZ[19]KM[7.50]
PW[Alphago]PB[Alphago]C[very slow games 2 mins/move
i.e. 8-10 hours/game

"The art of defence"

Fan Hui 2p (Deepmind)
Shi Yue 9p
Liu Xing 7p

This is from Fan's analysis of alphago's reading]RE[B+Resign]
;B[pd]
;W[dd]
;B[pp]
;W[dq]C[Shi: alphago likes to invade 3-3, but still plays 4-4?

Fan: It sees it as even, like a joseki]
;B[co]
(;W[fp]C[Liu: Nie is particularly fond of this move

Shi: whereas we don't like the fact B has a lot of ways for sabaki with attach C3, double hane, tiger, or crosscut

but this is faster than E4, and is better if W spends another move at C4

Fan: alphago strives for speed in the opening, and likes to play in the widest areas]
;B[cc]C[another of alphago's "playing cards"]
;W[cd]
;B[dc]
(;W[fc]
(;B[fb]C[but this game alphago directly attaches

Liu: humans normally play here, and W takes sente or plays G17]
;W[gb]C[Fan: no W doesn't tenuki, W blocks]
(;B[eb]C[but in the game, alphago directly pulls back]
;W[gd]
;B[ed]
;W[ec]
;B[bd]
;W[be]
;B[bc]
(;W[cf]C[Fan: the corner shape is standard, but the outside isn't]
;B[ee]C[Fan: W asks B to run out, and B does

Liu: neither side is scared of the other]
;W[df]
;B[ef]
;W[eg]
;B[ge]
;W[fa]
;B[db]
;W[he]C[Shi: alphago plays very differently with itself compared to with us. The self-play is normally very violent, but with us, it doesn't fight, but just builds up a steady advantage.

Liu: we always look for a fight, but it never works.]
;B[gf]
(;W[jc]C[shi: oh?

...

very logical

initially it looks very strange, but it seems the only move]
;B[cj]C[keeping up the pressure on this group]
;W[di]
;B[fg]
;W[ci]
;B[lc]
(;W[jf]
;B[ig]
(;W[qn]
(;B[ie]
;W[if]
;B[hd]
;W[hf]
;B[hc]
;W[hb]
;B[gc]C[Shi: this explains why W didn't play K13 earlier as that move would be useless

so though it is locally bad for W, B spends an extra move]
;W[nq]C[liu: B is very solid now, what do you think?
shi: I prefer W]
;B[np]
;W[mp]
;B[no]
;W[pq]
;B[qq]
;W[oq]
(;B[pn]
;W[op]
;B[po]
;W[qr]
;B[rp]
;W[rq]
;B[qp]C[liu: this is the first time I've seen this

fan: alphago still sees it as completely even]
;W[nc]C[settling the W group]
;B[nd]
;W[mc]
;B[md]
;W[lb]
;B[ld]
;W[kc]
(;B[qj]
;W[oc]
;B[od]
;W[cm]
;B[rr]C[not so big for points but huge as it is thick - if W got this, there would be problems with Q9]
(;W[qh]C[and alphago is very good at reducing the efficiency of opponent groups, such as with Q10]
(;B[lq]C[shi: tenuki is very strange we would normally try to attack when B has so much support

liu: W has two good points on the right at R15 with a hane and connect in sente and Q10, so perhaps it isn't so easy to attack, so harassing this is better

shi: and the invasion is probably good timing before B gets Q17, as W can make use of B not being alive

Fan: if B tries to attack now, perhaps there isn't any use. If there isn't a good move locally, alphago will tenuki

shi: and i think this is not necessary a double attack, this is just a big point. W gets a big point on the right, so B needs to take this big point

liu: yes, perhaps it isn't so complicated (as double attack)]
;W[mq]
;B[kp]C[Fan: with students, we say M3 loses terribly much, and you can't play it, but now we can't dare to say that.

Liu: we can't dare to teach anything anymore (laughter)]
;W[rs]
(;B[sq]
;W[ln]
;B[hq]
;W[qe]C[liu: now B really doesn't look like a thick group anymore

only groups with two eyes can be considered thick, so even the S2 group can't be considered thick.]
(;B[kr]C[fan: this looks very strange
I spent some time checking if this was a misprint


Shi: but this?

hmm, this is better for B's eyespace

Liu: if playing online, you would assume this is a misclick]
(;W[sr]C[wow!

Shi: normally if B was scared of this ko, B would play T2.

liu: it doesn't seem reasonable for B to connect at S3 because of the problem at Q9

but B also can't really afford to lose this ko as then the efficiency of the L2 is called into question

so this is a very good way to harass B

Fan: but actually if you look, W doesn't have ko threats]
;B[ss]
;W[em]
;B[pr]C[locally, W loses the eyespace and points, as the T2 throw in removes W's Q1 ko, but W forces B to spend a move on the 2nd line

W is very fast, getting 4 moves on the outside and the bottom right is light

B spent a lot of moves on the 2nd line to attack.]
;W[pj]
;B[pk]
;W[oj]
;B[qk]
;W[of]C[Fan: W is truly attacking B now

Fan: before we see the brillliant upcoming fight, let's take some time to judge the position and what both sides have as their purpose.

... after counting
Fan: what is W's aim?

Shi: W is aiming to save the N4 group in sente via attacking B and forcing B to run on dame and getting sente to protect the left side, say C4. Then B will find it hard to pay komi.

Liu: B's territory is about 46 with no potential, it will be hard for it to surpass 50.

but if W spends a move on the left, the left may already be 40 points.]
(;B[pg]C[shi: still trying to find W's weaknesses

liu: W already has 5 stones here

Fan: the best defence is attack

shi: in a real game you wouldn't necessarily have the courage to play here as B is in such danger and heavy]
(;W[og]C[shi: it is easy for B to get harassed]
;B[ph]
;W[qg]C[B's two stones are basically dead]
;B[pc]
(;W[qb]C[not even allowing an eye in sente]
;B[pf]
;W[pe]
;B[rd]
(;W[re]
;B[oh]
;W[nh]
;B[ni]
(;W[oi]
;B[mh]
;W[ng]
;B[mg]
;W[mf]
;B[lf]
(;W[mi]C[very violent]
;B[nj]
(;W[qf]
;B[pb]
;W[rc]
;B[rb]
;W[sb]
;B[ra]
(;W[qc]
;B[ok]C[very painful for W]
;W[pi]
;B[kg]
;W[ke]
;B[qd]
;W[sd]
;B[qa]
;W[sc]
;B[le]
;W[nk]
;B[mj]
;W[li]
;B[lj]
;W[ki]
(;B[hg]C[fan: somehow B connects up with one move]
(;W[kj]C[sente on the cut as there is the ladder]
(;B[kb]
;W[jb]
;B[mb]
;W[id]
;B[fd]
;W[ka]
;B[nb]
(;W[lp]
(;B[nl]C[fan: it seems like this is a big B success, not only living with points, but not really losing anything

liu: so it is now a big advantage to B?

fan: alphago still thinks it is a close game and tight]
;W[ko]
;B[jp]
;W[gr]C[if B responds and W gets C4, while W didn't really profit much from the attack, W can get the last big point.

Shi: and W succeeds in the plan we set for it - to save N4 in sente and to take C4]
;B[in]
;W[ll]
;B[mk]
;W[il]
;B[cq]
;W[cr]
;B[br]C[fan: from here, gradually W feels the position isn't so good and clarity appears in B's favour

liu: this sort of advantage, do you mean a large one

fan: no, I still mean very very small and close. And alphago thinks it is increasingly likely that B wins by 0.5 point]
;W[jg]
;B[ma]
;W[lr]
;B[kq]
;W[hr]
(;B[go]
;W[cp]
;B[bq]
;W[iq]
;B[ip]
;W[jr]
;B[mr]C[B can't accept W connecting under with lots of points]
;W[jo]
;B[io]
;W[hm]
;B[km]
;W[lm]
;B[hn]
;W[gm]
;B[gq]
;W[fq]
;B[gn]C[W does profit and P2 is sente]
;W[dr]
;B[cn]C[not scared of W killing the corner, saying the side is bigger]
;W[bm]
;B[dp]
(;W[do]
;B[dn]
;W[ep]
;B[en]
;W[dm]
;B[bp]C[liu: it is unfortunate W didn't get the chance to atari P2 in sente]
(;W[kh]
;B[gj]
;W[fi]
;B[ii]
;W[gh]
;B[gg]
;W[lg]
;B[fj]
;W[ej]
;B[eh]
;W[dg]
;B[kk]
;W[kl]
;B[jk]
(;W[im]C[fan: very interesting

liu: this looks like it clearly loses a point as K6 is sente

...

liu: very precise, and we know this is a 0.5 victory, so every point counts]
;B[fh]
;W[bn]
;B[ei]C[fan: B can't let W get this in sente

liu: it does look like B has a lot of ko threats whereas W only has 1]
;W[bo]
;B[dp]
;W[eo]
;B[fn]
;W[ek]
;B[cp]
;W[ri]
;B[rj]
;W[bs]C[comfortable]
;B[jn]
;W[jl]
;B[ls]C[preventing P2 sente]
;W[or]
;B[dh]C[shi: very precise and necessary

fan: critically important for the ko threats this gets]
;W[ch]
;B[ic]
;W[ib]
;B[qs]
;W[js]
(;B[ks]C[very precise, not clear whether to play O1 or not - fan: this is for a few extra ko threats]
;W[oo]
;B[nn]
;W[ae]
;B[jd]
;W[ik]
;B[ir]
;W[is]
;B[jq]
;W[ir]
;B[me]
;W[nf]
;B[kd]
;W[la]
;B[jh]
;W[kf]
;B[ij]
;W[ml]
;B[je]
;W[kg]
;B[jj]
;W[hk]
;B[fl]
;W[fm]
;B[gl]
;W[om]
;B[on]
;W[nm]
;B[pm]
;W[hj]
;B[el]C[shi: interesting, so these two pushes are miai]
;W[dl]
;B[ji]
;W[lh]
;B[hi]
(;W[ol]
;B[de]
;W[ce]
;B[pl]
;W[nk]
;B[dj]
;W[dk]
;B[nl]
;W[ns]
;B[ms]
;W[nk]
;B[mo]
;W[lo]
;B[nl]
;W[gp]
;B[hp]
;W[nk]
;B[bj]
;W[bi]
;B[nl]
;W[ob]
;B[oa]
;W[nk]
;B[bg]
;W[cg]
;B[nl]
;W[mm]C[liu: B has too many ko threats]
;B[ea]
;W[ga]
;B[qi]
;W[sh]
;B[ai]
;W[ah]
;B[aj]
;W[bh]
;B[ao]
;W[ad]
;B[ac]
;W[an]
;B[sj]
;W[nk]
;B[lk]
;W[ap]
;B[si]
;W[rh]
;B[nl]C[B wins this ko and W is unable to throw in at Q1
so B wins by 0.5 point

note W needs another move at B9

shi: its endgame is so precise])
(;W[de]C[shi: isn't this 1/3 point better as W no longer has to spend another move inside the area

liu: probably the 1/3 point doesn't affect the game result]))
(;B[ns]
;W[os]
;B[nr]C[B gets 2 points not 1, but the R2 potential is gone from ko to nothing

but B doesn't have the J2 etc ko threats]))
(;W[jl]C[normal]
;B[fl]C[shi: oh, very interesting]
;W[fm]
;B[ek]
;W[ei]
;B[dk]
;W[hj]
;B[hk]
;W[hi]
;B[ik]
;W[gi]
;B[lk]
;W[gk]
;B[gl]
;W[fk]
;B[hl]C[now this becomes relevant]
;W[im]
;B[el]))
(;W[eh]C[liu: like this W seems to make a lot of points, B has 60, W has close to 60]
;B[kk]C[fan: I was surprised too, isn't W alive, but alphago was going to play here]
;W[kl]
;B[jk]
;W[jl]
;B[ii]C[shi: nice move]
;W[jh]
;B[gj]C[and B is threatening J17]
(;W[ic]
;B[fk])
(;W[fk]
;B[ic]
;W[jd]
;B[ib]
;W[la]
;B[ia]
;W[ja])))
(;W[eo]
(;B[bn]
;W[do]
;B[bp]
;W[ao]
;B[an]
;W[bs]
;B[dm]
;W[ck]C[liu: I find Fan is a bit unsure now when faced with Shi Yue's famous killing ability]
;B[dl]
;W[dj]
;B[dn]
;W[en]
;B[fl]C[probably B can utilise weaknesses at H5 and L9])
(;B[dm]C[shi: oh directly here is even better]
;W[ck]C[necessary]
;B[do]C[W in trouble])))
(;B[ir]C[liu: what about this?]
;W[hp]
;B[mr]
;W[iq]C[this is still sente

shi: ]
;B[]
;W[bq]C[shi: this is powerful if W is very solid]
;B[cp]
;W[bs]))
(;B[ko]
;W[lk]
;B[lo]
;W[mo]
;B[mn]
;W[nn]
;B[mm]
;W[oo]
;B[nm]
;W[lr]
;B[kq]
;W[ms]))
(;W[lk]C[fan: why not here]
;B[mo]
;W[lo]
;B[lp]
;W[oo]
;B[nn]C[fan: oh]))
(;B[mb]C[fan: why not this side?

...

liu: perhaps it thinks this loses too many points]
;W[nb]
;B[ml]
;W[jg]
;B[jh]
(;W[id]
;B[fd]
;W[kh]
;B[kb]
;W[ma]
;B[kd]
;W[jd]
;B[jb]
;W[ih]C[laddered]
;B[ic]
;W[je]
;B[ib]C[W is dead])
(;W[je]C[liu: perhaps alphago is scared of this variation - there is still a cut])))
(;W[jg]
;B[jh]
;W[id]
;B[fd]
;W[kh]
;B[mb]
(;W[nb]
;B[kb]
;W[ma]
;B[jb]C[W dies])
(;W[kb]
;B[nb]
;W[ma]
;B[ib])
(;W[jb])))
(;B[jg]C[this would be a disaster]))
(;W[qa]C[Q19 is sente for N18]
;B[pa]
;W[sa]
;B[mb]
;W[nb]
;B[na]
;W[ma]
;B[ob]))
(;W[lg]C[liu: W just doesn't have the ladder due to H3]
;B[lh]
;W[li]
;B[kh]
;W[nk]))
(;W[qf]C[W could have just protected without giving up the P9 sente]
;B[kh]C[and then alphago would play here

Liu: this is tewari of]
;AE[pe][lf][mf][pf][qf][mg][ng][og][pg][qg][kh][mh][nh][oh][ph][ni][oi]
;W[]
;B[mg]
;W[mf]
;B[lf]
;W[ng]
;B[mh]C[this is unreasonble as there is the M13, but the game is as if W responded]
;W[nh]
;B[ni]
;W[oi]
;B[kh]
;W[]
;B[pf]C[these exchange lose a few points, but not too much]
;W[pe]
;B[pg]
;W[qg]
;B[ph]
;W[og]
;B[oh]
;W[qf]C[as now P10 also loses liberties



so this result looks good for B

Fan: and perhaps why W could have gotten this variation so easily but sacrificed shape with the N11 atari.]))
(;W[mg]C[shi? why not here?]
;B[nj]
;W[rc]C[and then here?

Fan: alphago agrees]
;B[qi]
(;W[kg]C[defending against L15 and then M13]
;B[km]C[alphago thought this was also a reasonable game

both sides gain about 40 points, M12 is sente, W gets sente, and there is still aji with the M6 group


shi: this is why B poked at Q13 rather than just running as B could sacrifice the wall

liu: that poke looks simple, just one move, but contains a myriad of variations behind it to read and judge])
(;W[lh]C[shi: why not here, this helps the centre a lot more

fan: perhaps F16 is now sente?

Liu: W will give up L18 though

fan: and p15 is sente

shi: oh, yes, ...]
;B[oe]
(;W[]
;B[qd]
;W[sd]
;B[pb]
;W[rh]
;B[pa]C[double sente on N18 and S18])
(;W[qd]
;B[kg]C[fan: this seems to give B even more sente on the outside]))))
(;W[pb]C[fan: I seriously wondered why not here]
;B[pi]
;W[qi]
;B[oi]C[wow]
;W[ni]
;B[nj]
;W[ok]
;B[nh]
;W[mi]
;B[oh]C[shi: this looks unacceptable for W

B's wall looks thick again]))
(;W[rc]C[normally you would think here ]
;B[ob]C[alphago would play here]
;W[nb]
;B[rb]
(;W[qb]
;B[rd]
;W[sb]
;B[ra]
;W[qc]
;B[qd]
;W[pb]
;B[pf]
;W[pe]
;B[qf]
;W[re]
;B[rf]
;W[sd]
;B[oe]
;W[se]
(;B[mg])
(;B[oh]
;W[mg]C[shi: even like this B can be content perhaps]))
(;W[rd]
;B[oa]C[B gets an eye in sente])))
(;W[qg]C[if here]
;B[lg]C[alphago plays here, and it is hard for W to keep up the attack]
(;W[]
;B[pf]
;W[pe]
;B[og]C[this is severe])
(;W[ng]
;B[kh]
;W[lf]C[shi: if here?]
;B[mf]C[liu: B is probably ok...]
;W[le]
(;B[pf]
;W[mg]
;B[pe])
(;B[nf]C[not ok]
;W[mg]
;B[og]
;W[me]
;B[ne]
;W[oh]))))
(;B[mg]C[shi: my first feeling is still to run]
;W[mf]C[fan: alphago would play here]
;B[lf]
;W[ng]C[W attacks while fixing the weaknesses]
;B[lh]
;W[ke]
;B[le]
;W[lj]C[liu: this is how W will get sente to protect the left and win like we said before])
(;B[lg]C[if directly ]
;W[ok]
(;B[ng]
;W[mh]
;B[mg]
;W[nm]C[B gets sente, alphago thought this was also possible])
(;B[pg]C[no longer possible]
;W[og]
;B[ph]
;W[qg])))
(;W[pk]C[fan: in checking many of the variations such as if L2 was at M2, W is aiming to play here, so T2 probably really does matter]))
(;B[jn]C[shi: to follow up here, I would normally consider this or])
(;B[lr]C[this would mean W immediately has only half an eye

actually alphago thought this was also possible ]
;W[nn]C[I checked what alphago was thinking]
;B[kn]
;W[ko]C[this is now possible]))
(;B[sr]C[liu: it is hard to choose between these moves

the difference is very tiny, and it is very hard to judge

shi: if W connects at Q2, this is slightly better for points, but if B is surrounded T3 is more flexible shape to live

and if W tries to make life with Q1, then capturing may be better to leave the move at T1 to attack W's eyespace.

Liu: but really, all these possibilities are very unlikely, so it is very hard to choose.]))
(;B[kp]
;W[mo]
;B[lq]
;W[nn]C[shi: peeping first is a shape and very good order as if you attack first, W can get shape with this atari

but if you peep first, O5 is light]))
(;W[mo]C[Shi: I would probably play here as W is very wide as well

and as W has Q17, invading the right is not so urgent

Liu: me too

Fan: for alphago, this was another option it could have chosen, both very big

probably it invades because it is still eyeing the life and death of the b wall above]))
(;B[oc]C[Fan: we were always taught this was very big so why not here?]
;W[qi]C[Shi: perhaps it is as W is completely alive, so P17 is purely points and not so urgent]))
(;B[qp]C[Liu: perhaps B avoids this because F4 makes W more solid]
;W[qk]))
(;B[nq]
;W[nc]C[if B responds, W would start a fight]))
(;W[jg]C[Fan: because it isn't so easy for W to play locally]
;B[ie]
;W[if]
;B[hd]
;W[hc]
;B[hf]
;W[je]
;B[ih]C[B can peep at L18 and then at L16, very painful]))
(;W[je]C[more standard]
;B[hf]C[but alphago would play here])
(;W[ig]C[Shi: but then why not here?]
(;B[hf]
;W[if])
(;B[hd]
;W[hc]
;B[id]
;W[je]C[Liu: W is happy])))
(;W[id]C[normally you would think about this

Liu: but you fear the peep

Shi: yes true]
;B[hc]
;W[gc]
;B[hf])
(;W[jd]C[this might be even worse]
;B[hf]
;W[ie]
;B[hc]))
(;W[df]C[Shi: If I played, it would be here as I think B is completely alive, and it is not as if W has a helping stone at C10 for the fight

Fan: I think it is because in the game W can protect nicely with one move, so it expects B to pull out immediately, but like this, W doesn't have a good local follow up either. My understanding that this isn't as good as forcing B out for a fight because]
;B[ck]C[Liu: for example, though W doesn't need to protect yet, there is still the aji of F15

so W still owes a move, but if W protects it is worse than if D14 was at C14]))
(;B[ec]
;W[fd]C[W is preparing this]
;B[ed]
;W[ee]
(;AE[fb][gb][cc][dc][ec][fc][dd][ed][fd][ee]
;B[ed]C[Liu: this is very similar to]
;W[ee]
;B[cc]
;W[dd]
;B[dc]
;W[fd]
;B[ec]
;W[fc]
;B[fe]
;W[ef]
;B[bd]
;W[be]
;B[bc]
;W[cf]C[Liu: in this joseki, F18 is a bad exchange]
(;B[fb]
;W[gb])
(;B[ge]))
(;B[fe]C[Fan: and alphago will also ]
;W[ef]
;B[bd]
;W[be]
;B[bc]
(;W[he]C[but W will play here

Liu: that's a very strange move!]
;B[ce]C[if here]
;W[ff]C[alphago just defends

Liu: very strange!

Fan: alphago thinks W is slightly better. it emphasises centre influence

Liu: and it uses it very well])
(;W[ge]C[Liu: we should emphasise that if W has the ladder it should still be here])))
(;B[ed]C[shi: so why doesn't it play here in the first place?

liu: ah that's a good idea]
;W[ee]C[shi: probably because W is not scared of E17 as that is the same as the other variation]
;B[eb]
;W[fd]C[W won't tiger anymore]))
(;B[ec]C[normally alphago plays here]
;W[ed]))
(;W[ed]C[Shi: I'm not sure what the difference with this move is

Fan: probably it is dependent on the surroundings]
(;B[ec]
(;W[fc]C[the same])
(;W[fd]C[or here]))
(;B[fc])))
(;W[ep]C[it almost never plays here, sometimes it tenukis and even less it pincers]))
