(;GM[1]FF[4]CA[UTF-8]AP[CGoban:3]ST[2]
RU[Chinese]SZ[19]KM[7.50]
PW[alphago]PB[alphago]C["What counts as true thickness"

Tang Weixing 9p
Liu Xing 7p
Fan Hui 2p (Deepmind)

Translated by Daniel Hu 5d

49:57
1:16:23

Liu: I'm sure these 50 self-play games released are very interesting to amateurs and not just professionals

Fan: But many amateurs tell me the games are spectacular, but we can't understand any of it, so that is why we wanted to explain the moves in this series.

Liu: Tang, you were at Wuzhen, so do you have any thoughts?

Tang: Well, it was certainly very strong and quite soon, it felt like we couldn't find good moves. And its true: I've looked at some of the 50 self-play games, but very little is understandable.

It is as if all sorts of moves are playable now, but we can't understand why.

Liu: just to clarify, Tang hasn't seen any of these games before, but Fan and I have discussed them a little.

Fan: so we can see Tang's first instinct and interesting reactions.]
;B[qd]
;W[dp]
;B[pq]
;W[dc]
;B[ce]
;W[oc]C[Liu: a standard opening strategy]
;B[pn]C[Fan: this appeared in the 50 games all very similar]
;W[ci]
(;B[pc]
;W[od]
;B[pf]C[Liu: I want to ask about this kick and keima

...

but in this case, it kicks first. Is this because of the whole board situation, or just chance?

Fan: it does like keima directly often, but in different situations, it does choose alternatives, such as the C11 pincer, or this kick.

As to the meaning, I'll ask Tang sensei.

Tang: this question, well, ... that's a bit deep and mysterious.

]
(;W[kd]C[....


Fan: but eventually in the set of moves considered, it eventually settled on this move]
;B[ed]C[and black still pressed with the knights move

...

Fan: in this case, W can't accept crawling right?]
;W[dd]
;B[de]
;W[ee]C[Liu: W has a similar thought process to us, that W should use the advantage of stones locally to fight here]
;B[fd]
;W[ef]
;B[dg]C[Fan: getting very complicated]
(;W[ge]
;B[gd]
;W[cd]C[Fan: are there any other possibilities?

...

Liu: but it's true that after the jump, B does urgently need to manage the 3 stones at the top

]
;B[bd]
;W[bc]
;B[be]
(;W[fb]C[Tang: now B can't make a net with F13, so has to escape via H15

Fan: in the 50 self-play games, there were two games like this]
;B[bb]
;W[ab]
(;B[jd]C[Liu: we would normally see this as sabaki

]
;W[je]
;B[id]
;W[kc]
;B[gf]C[Liu: a vital point

Fan: the shape is here

Tang: still within our understanding

]
;W[eg]C[Fan: but when W pushed, B's play was rather special.]
(;B[db]
;W[ec]
;B[cb]
;W[cc]C[Fan: all forced]
;B[eb]C[Liu: directly shorting W's liberties.]
;W[fc]
;B[gc]
(;W[gb]C[...

Tang: well, it thinks that the ko isn't an issue right now, and for now, it is hard for B to deal with both weak groups.

Fan: it has something to do with liberties?

Tang: it must be as otherwise, it should be better just to live.

...

Fan: both sides are playing very tightly here]
;B[hb]
;W[ba]C[Liu: what is the state of the corner?

Tang: a one step ko in W's favour, either C19 or F19]
(;B[dh]
(;W[hf]
;B[he]
;W[fe]
;B[if]
;W[hg]
(;B[jb]C[Tang: really surprising ...

...

Tang: this requires a lot of reading and courage

Fan: a determined move

Liu: I'm sure a human would have to calculate for 30 mins to have the courage play this move. Because the subsequent ko, threats, exchanges and judgement are extremely complicated.

Tang: and W will already profit a lot on the outside, so if it is only a one step ko, it is risky.

and W isn't that thin on the outside, so any ko threats will be bad exchanges.]
(;W[ie]
;B[hd]
;W[ke]
(;B[gg]C[Fan: before starting the ko, B plays here

Liu: although B can live at the bottom, but B can't consider spending a move to live. W's outside is already very thick and complete, so B would be dissatisfied.

Tang: so W will hane I suppose]
(;W[df]
;B[cf]
;W[eh]
;B[fa]
;W[ga]
(;B[hh]
;W[ig]C[Tang: so B did actually atari before A16. Its move order is very precise.]
;B[ad]
;W[ac]
;B[ca]
;W[ea]
;B[aa]
;W[cg]
(;B[bg]C[Tang: so B has to respond]
;W[ba]
;B[jg]C[Fan: this time, W can't end the ko as the left side is far worse.]
;W[ih]
;B[aa]C[Liu: it seems like W doesn't have a great ko threat]
(;W[di]C[Fan: in the real game, W chose to play a big move

Tang: to sacrifice the ko

]
;B[ha]
;W[ba]
;B[ii]
;W[jh]C[Fan: W has to respond to this]
;B[aa]
;W[qe]C[Liu: Tang sensei foresaw before all this that we might have this sort of exchange]
;B[fa]C[Fan: very shocking to the senses! a swathe of black.]
;W[re]C[Fan: how many points of territory are there?

Liu: if we count 3 points on each side

Tang: if B captures C13 it is already 4 points, so count 4 points there and 3 points on the top.

Liu: it is easy to count the 12 captured stones. There is 29 points of territory, but actually W captured a stone within it, so it is 28. Adding the extras, it comes to 35 points.

Fan: it looks like a big chunk, and 35 points is not small, but it isn't so scarily either.

Liu: this is the most difficult part of go: judgement. If it is just about calculation, if we spent a lot of time, we can probably reach these variations. But to evaluate it ...

Tang: The outside is very nice. My first instinct is that with the 35 points, B isn't very satisfied.

and W is ok, as the centre ko threats lost a lot and W is very thick. and W got a very big move at R15. and W has another corner that works well.

My first instinct is that I prefer W.

Right now, I'm sure B will sacrifice the corner, extend on the side (points around R11) and W probably has to spend another move

Fan: oh so, the corner is still not dead yet?

Tang: no it's not

Fan: can it live?

...

Liu: so can Fan sensei give us a judgement?

Tang has already said he thinks it is close but prefers W.

Tang: well that was my first instinct, but I think we do need to evaluate the influence first.

And see if B spends a move, if the influence isn't very big, then maybe I'd choose B. But first instinct is W is not bad.

Fan: alphago thinks that the position is even. The fact that both sides were willing to accept this position means that it must be close.

Liu: So it is still a long game, playable for both sides.

Fan: they've just played out a big joseki (chuckles)!

Liu: a huge joseki!]
(;B[fq]C[...

Fan: if B can get this exchange, B can get all 3 big moves. Hence in the game, B chose this point.]
(;W[ji]C[Fan: a very interesting move

Liu: feels like a move with a lot of aji (wei4 dao4 = taste).

Tang: it is all about the value of the centre influence

...

Fan: this seems like a "gote no sente" (hou4 zhong1 xian1) move. Very thick, though it is gote.

Liu: my question is that did W not answer in the corner because it thought is wasn't big?

Tang: I think it isn't big, and it is also hard to find a good response.]
;B[pe]
;W[pd]
;B[qh]
;W[qc]
;B[pk]C[Liu: also a very big move]
;W[er]C[Tang: I still prefer B playing a move in the centre first as I feel like the F3 approach wasn't the urgent point. Now W is out in the centre, the shape on the right isn't anything special.]
;B[iq]
;W[nq]C[Liu: in this sort of shape, isn't this a standard invasion point to consider?

It makes miai of two good points L3 and R3.

Fan: R3 is the weakness of the two space high extension shape

Liu: though it is also a weakness for the two space low extension.

Though in that case Q5 is a possibility

...

Fan: in the game it chose a rather different possibility

Tang: it is hard to work out what is best here. Perhaps tenuki?

Locally what is the situation after W attaches at R3?

...

Tang: So if it we've calculated that it is difficult to play locally, perhaps B can tenuki and play on the left side?

Liu: as the proverb goes, when it is hard to find a response, then don't respond.

Tang: if B can take sente to invade, then it also seems like a very big move.]
(;B[cn]C[Fan: Tang's sense of direction is very good.

In the game, B played here.

Tang: though I didn't consider this as an invasion point.

I thought that if we were trying to invade, then something like B5 was natural.

This approach move is fighting directly. Doesn't it seem a bit hard to manage?]
(;W[bp]C[Fan: no, W just simply jumped

Liu: At the time, I was shocked.]
(;B[jj]C[Fan: in the game, it played a pretty move

Tang: I was wondering if this was possible.]
(;W[hi]C[hence in the actual game, it double ataried.

Both sides emphasise thickness and aji]
;B[ij]C[Tang: forced]
;W[gh]C[Liu: at least from B's perspective, I think B can't do better than this. To get the two moves at J10 and K10 in sente, B should be very happy.

]
(;B[kp]C[Fan: after the profit, it then adds a move here.

...

Liu: if W doesn't play to live in the corner, what else can W play?]
(;W[po]C[Fan: a very interesting move]
(;B[oo]
;W[qq]C[Fan: now it attaches.

Tang: that is a very interesting plan

...

Tang: this is a myoshu! (brilliant move)

Liu: and great when W wants to live on the lower side (compared to the corner)

Fan: it's not necessary a global strategy. Just locally, it is a useful tesuji.

Tang: but you do need to be careful what situation you use this in.

Liu: viewers should be aware that the Q5 wedge is a very bad exchange.]
(;B[pp]C[Tang: so it seems like this is the only move]
;W[pr]C[only move

Fan: this seems like the 3-3 invasion, but W just wedged at Q5.]
(;B[rp]C[Fan: so in the game, B chose the jump. Making it harder for W to live

Trying to maximise the loss of the Q5 wedge.

Tang: yes]
;W[or]
;B[rq]
;W[lr]C[Liu: getting stability.

Fan: they achieved a compromise.

And it is still even.

...

Liu: so for W to live like this when B has so many stones is not bad.

Tang: it is good for W (if B plays the R2 exchange), but B won't make that exchange.

R2 isn't very big

Liu: so locally this should be even.

Fan: yes alphago thinks it is even, and very close, with both sides playing very tight.

Liu: in so many of the self-play games, the margin of the game is a half-point victory. From this we know we are watching masters play!

Fan: In many of the games you see huge fights, life and death and exchanges. And many of these are played simply because one side thinks it will lose by 0.5pt if it doesn't fight.

Liu: it isn't like humans, who will fight desperately when it is obvious they will lose by a lot otherwise.

Fan: for alphago, 0.5 point is "obviously" insufficient.

Tang: Right now, it can't calculate whether it is a half point victory or not so it says it is even. Perhaps in the future it will advance enough to know.]
(;B[en]
;W[fr]C[Liu: at the time, I asked Fan sensei. Though the turn in the game thickly emphasises the G11 atari. For points, isn't the M10 jump very big too for the B moyo?

As B is already thick as iron on the left, but there are more points on the right]
(;B[hj]C[Liu: this turn seems to be emphasising the G11 atari. It is difficult to judge whether it is better to let B atari or to :]
(;W[kj]
;B[kk]
;W[lj]
;B[gq]
;W[lk]
;B[kl]
;W[ll]
;B[km]
;W[om]
;B[pm]
;W[gk]
;B[gj]
;W[fk]
;B[dk]
;W[fj]
;B[gi]
;W[fi]C[Fan: I think W's plan is to never have to connect in response to the G11 atari.]
(;B[hl]C[Liu: it seems that B didn't end up surrounding much territory.

Fan: it just got thicker such as with G3]
;W[oi]
;B[pi]
;W[oj]
(;B[pj]C[Fan: if B doesn't connect, what problems are there?

...

Tang: so just connecting is better, but it's surprising.

Fan: it looks so submissive, as if B is in too good a mood.]
;W[og]
;B[hh]
;W[fh]
;B[qf]C[Tang: B's turn is also very big, so to judge between P12 and Q10 is about which of these moves is bigger.]
;W[rf]
;B[rg]C[Tang: this game has been so complicated the whole way, that if it were humans playing, both sides would be muddled, too tired to work out who was leading. B would probably fight at P12 anyway.]
;W[fm]C[Fan: from here, W starts to get a lead

Liu: wasn't it always very close?

so it is gradually trending towards a 0.5 point W victory.

Fan: when I play, if the game gets to counting, I tend to lose hope as I always miscount points.

Liu: and right now there are still some unclear shapes. For example, how many points does B have in the centre or on the left?

Tang: B's 2 big areas are about 60, and adding the centre makes about 70.

For W, B can jump at O15 and W can respond at O14, so W can count at least up to that line.

W's main area is 41, or a bit more. Count 5 for the lower right and 11 on the lower left. So W has a bit over 60 in total.

It seems like the game is still complicated.

Perhaps W is slightly ahead.

Liu: Yes, because Tang counted quite little for W, not counting M,N,O 14. And just counting two points at the top: P18,19. So if W adds a move at L18 or Q12 it will be more.

Fan: so from here, B played quite aggressively.]
;B[bo]
;W[co]
;B[bn]
;W[ep]
(;B[bj]C[Fan: this is a very big move

Liu: with a crawl follow-up.]
;W[kq]C[Liu: Threatening B, but if B responds, then W profits in territory.]
;B[gn]C[Fan: reinforcing the centre]
;W[fn]
(;B[fo]
;W[gm]
;B[hm]
;W[bh]
(;B[ne]C[Fan: B was panicking here, so started to play desperately

Liu: against us humans it would never need to play so desperately, and we would already have lost before the endgame.

Fan: oh, it would be different for you, but I would already have given up long before endgame.

Liu: really, but are you the world number one at the first 50 moves.

Fan: oh no, absolutely not!

Tang: we should set up a competition (with alphago?) where we have you play the first 50 moves.]
;W[dm]
;B[dn]
;W[jp]
(;B[go]C[so in the game B had to accept connecting and give up the points in the centre.]
;W[jn]C[Liu: and not only does B not have points, but B is still very thin.]
(;B[nf]C[Fan: so B snatched another big move

Liu: not giving W any respect]
;W[bl]C[Tang: O14 really does look desperate.

Liu: spending two moves in a row elsewhere.]
;B[cl]
;W[dl]
;B[cm]
;W[jm]
;B[jl]
;W[eo]C[Liu: whenever alphago plays this cut, it is no longer just acting (aggressive) anymore.

right now both B groups seem to be in trouble]
(;B[bk]C[...

Fan: in the game B bumped]
(;W[hn]C[Fan: but B's problem is that there isn't just one weak group.]
;B[in]
;W[im]
;B[ho]
;W[il]
;B[bq]C[Fan: B play is starting to look like a mess]
;W[ap]
;B[hk]
;W[am]C[Liu: what is the meaning of the kosumi?

Tang: nothing special, just trying to kill.

Fan: B thought that it was trouble here too.]
;B[ai]C[Liu: I understand. So right now W is satisfied to capture either of the B groups. It isn't as if it has to capture both, or capture a particular one.]
(;W[ko]
;B[lm]
;W[ah]
;B[dr]
;W[br]
;B[em]C[Liu: when it starts to play these sorts of meaningless timesujis, then ...

Fan: it can't see hope of victory.]
;W[el]
;B[bm]
;W[al]C[Liu: W is forcing B to use the A5 sente]
;B[ki]
;W[jf]
;B[kg]
;W[kh]
;B[bi]
;W[ao]
;B[an]
(;W[eq]C[Liu: why doesn't it defend more safely?

Fan: it's all safe to alphago]
;B[ak]
;W[mm]
;B[cq]
;W[cp]
;B[ar]
;W[bs]
;B[mn]
;W[ln]
;B[ml]
;W[nm]
;B[li]
;W[nk]C[Liu: the outcome is clear]
;B[ip]
;W[lp]
(;B[cs]
;W[aq]
;B[jr]
;W[hr]
;B[gr]
;W[gs]
;B[cr]
;W[dq]
;B[as]
;W[br]
;B[bs]
;W[es]C[Fan: B resigned here

B is behind by one liberty. and the large dragon only has one eye.

This game was quite interesting. A huge exchange in the opening, and then a complex killing battle.

Tang: in many of the alphago games, some moves are very hard to understand, some are very easy. I thought that this game was relatively understandable after some slow analysis.

Fan: can you give a summary of the game? How was it?

Tang: Well, you didn't show me the kifu to start with. My first instinct was that in the 50 self-play games, much of it was incomprehensible. But I thought this game was more like human play.

It was very spectacular in the upper left and lower right.

But after some analysis, it does seem clear.

Fan: I think that it is also because we've gotten to see some more alphago variations, and from these, we can justify these moves better. And understand more than we used to. And then discover that they are not so mysterious as they initially seemed.

Tang: Its hard to understand many of its moves, but it's probably because they contain a lot of hidden calculation.

For example, the O15 move was because we counted that if W got to play L18, then W would be winning.

And before that, it seemed very close. And the positional judgement was confusing. Alphago does seem to be very strong at calculation.

Fan: Calculation is one thing. But its ability to judge a position, and foresee how the game will continue is incredible.

Tang: Its calculation and judgement are joined together. Some people are very good at reading, but can't judge clearly. Others judge clearly, but can't calculate.

Liu: Both issues are deadly.

Tang: You can judge that a position is good for you, but if you can't win from it, then your skill level won't be great.

Fan: so it has both calculation and judgement, so it is very strong.

Tang: and it doesn't have weaknesses, so if you want to win against it, you have to be winning all the time.

It isn't like some people who have a style, and you can prepare against it by thinking about how to counter it.

Against alphago, if you can beat it, then you can beat it. And if you can't then you can't. It's that simple.

Fan: For example in Europe, we don't have to niggle into the details over who is stronger. Instead, it is a tool. The question is how we can use it to better understand the world of go.

Whether it is particular moves, or ways of thinking, or the Q5 attachment followed by the 3-3.

Including the atari, or the gote thick centre move, and the whole series of things. I think these are perhaps the most important things alphago can teach us.

Liu: Yes. Can you each tell us what your strongest memories of this game have been?

Tang: The opening fight seemed to be very logical. And if a human could play Q5, they would have to be very talented.

Fan: I've seen so many these games, so I'm a bit desensitised.

I thought that the G5 point was very pretty, in the variations. If B didn't pull back at G3 and turned in the centre instead.

Liu: There are a lot of brilliant variations behind each move.

Fan: We wanted to show people some of the content of the games, so it isn't just like (reading a book?)

Liu: I was most interested that when B haned in the centre, W didn't cut to fight, but instead captured a stone in gote.

Fan: I guessed that you were going to say that.

Liu: even I felt that the result might be insufficient in the variations, I would still cut to fight. 

Fan: you wouldn't want to already have given B profit.

Tang: Though if we consider how it (B or W?) had to make life, then the centre double hane wasn't necessarily profitable.

Liu: originally, B did have the possibility of still running out with the stones (with G11). In the game, W solidly captured them and could be comfortable.

Fan: it seemed like the value of the centre was actually not very high.

Liu: anyway, I think we learnt a lot this game.

Tang: Yes, thanks to Fan sensei for bringing the game record.

Liu: we look forward to seeing more. see you next time.])
(;B[mi]
;W[mj]C[Liu: right now we can see that W can connect back with the O5 clamp.

and also, as O11 is sente, W can live.  ]
;B[no]
;W[ni]))
(;W[cr]C[if it were me, I might defend here]))
(;W[dr]C[Liu: so for example, if W solves the problems in the corner, then B has to save the group

Tang: otherwise A12 will kill B]
(;B[ah]
;W[ko]C[Fan: if B can't run out then this dragon will be dead.]
;B[lm])
(;B[]
;W[ah]C[this is unconditional kill as]
;B[bi]
;W[ao]C[W can turn in sente now])))
(;W[aj]C[Liu: this kills but

...

B must be using that A5 will be sente, and then try to cause problems in the corner.]
;B[ao]
;W[am]
;B[bq]
;W[ap]
;B[dr]C[Tang: W's liberties really are quite short. There do seem to be some problems.

]
;W[eq]
;B[br]C[Liu: there may be a semeai

Fan: hence, B shouldn't be dead locally.]))
(;B[ai]C[Tang: so B should kosumi I think?]
(;W[ah]
;B[bk]C[Fan: seki])
(;W[bk]C[Tang: is this possible then?]
;B[ck]
;W[ah]C[Tang: it seems like B is not alive])))
(;B[em]C[Liu: and B can't push through very strongly as


...

Liu: and actually if B spends a move defending, say here, then if W responds on the top right, it isn't such a big deal.

and furthermore, it is hard for B to choose a good place to defend.]
(;W[dl]
;B[el]
;W[ck]C[the shape is broken])
(;W[oe]
;B[of]
;W[nf])
(;W[nf]C[or here])))
(;B[]C[Liu: W's meaning is that W can ]
;W[go]
;B[hn]
;W[fp]C[this is sente, so B has to make life now. But W doesn't make these exchanges yet.])
(;B[jq]
;W[ko]
;B[lp]
;W[jo]
;B[lo]
;W[go]
;B[hn]
;W[fp]C[game over

Liu: surely however W plays on the left, W will be dead. So W is in trouble. ]))
(;B[eo]C[Liu: so Fan's meaning is that normally B should defend

Fan: alphago thought that this was the proper move, but that the game was ]
;W[go]
;B[hn]
;W[fp]
;B[gp]
;W[dn]
;B[dm]
;W[em]C[snapback]
;B[ho]
;W[do]
;B[cl]
;W[cj]
;B[bl]
;W[kb]C[Fan: It thought that it was very close, but that W had a better chance of victory in this position.

W got to profit a bit and then take sente for L18, so if it was good for W before, it certainly should be now.

Liu: But if it were humans playing the endgame, then I think it would still be 50-50 odds, or perhaps 55-45.

Tang: I do think W is ahead, but I'm not sure that it is 0.5 point win, and it could be 2.5.

Fan: Oh, I'm not sure either. It could be 2.5

Tang: I think W's lead isn't just a little. W's lead is pretty clear.

Fan: when I counted, I also thought W was ahead. Of course, my skill level is much less, but I did think that.

so I can understand why B was desperate

]
;B[ne]C[Liu: now W can cut]
;W[oe]
;B[of]
;W[nf]
;B[ng]
;W[mf]
;B[oh]
;W[nh]
;B[pg]
;W[mg]
;B[ni]C[Liu: B can't necessary get this exchange in, but even if B does, then  B can't capture W]
;W[mh]))
(;B[bi]C[Liu: I have a question: what if B plays G6, pretending it reinforces the centre, making a profitable exchange and then connects up on the left?

"Choosing cash over safety"

Fan: Let's test Tang sensei again.

Tang: Actually I was wondering about this question too.

Liu: B is certainly thin, but is there any severe follow up?

Tang: K4?

Fan: we dug a pretty deep hole this time.

Liu: should we let Tang try a few moves or let Fan give us the answer?

Fan: Alphago's answer just looks nice. Once you see it, it just looks right. That it must be there.

]
(;W[io]C[Tang: not here?])
(;W[il]C[Tang: then here?

Fan: this is truly a sign of a top player's shape instinct.

alphago would also play here]
(;B[im]C[...

Fan: alphago thinks hane is the only move]
;W[hm]
;B[hn]
;W[hk]
;B[ik]C[Fan: B has to let W capture this]
;W[gl]
;B[lp]C[Fan: B's loss is already quite serious.

Liu: And when W captures later, B has a lot of problems]
;W[hi]
;B[jk]C[W can still harass B

Fan: hence B didn't dare to take B11.])
(;B[hk]C[if here, then B's liberties seem even tighter and B will really be in trouble.]
;W[in]C[W just needs to jump.]))))
(;B[fn]C[Liu: B can't accept connecting up through here, as even though B can connect up, but it gives up all B's territory]
;W[gm]C[and B is still thin]))
(;B[oh]
;W[nh]
;B[og]
;W[ri]
;B[qi]
;W[ok]C[Liu: perhaps press?]
;B[pl]
;W[rg]C[Liu: B's shape is strange.
Tang: P12, 13 doesn't seem so big

Liu: W gets to squeeze B's territory on the side and press from above.]))
(;B[hh]C[Tang: why not capture first?]
;W[il]C[probably this]
;B[fh]
;W[in]))
(;W[gj]
;B[gk]C[let B get the F10 atari]))
(;B[lj]C[Tang: I don't agree.

I think B is quite thin on the left, and the turn protects it perfectly.]
(;W[gl]C[Tang: After this, it feels like B can't make points

M10 feels like adding thickness to thickness.

])
(;W[go]C[Fan: alphago would play here and B can't connect easily and becomes very thin.
...

Tang: this move is on the territory]
;B[]
;W[io]C[Liu: W's next move is here.])))
(;B[qr]C[Liu: if B ataris later. Then I think the tewari goes like ...]
;W[kq]
;AE[oo][po][kp][pp][rp][kq][qq][rq][lr][or][pr][qr]
;B[oo]C[as if B played kosumi in response to the approach]
;W[pr]
;B[qr]
;W[or]
;B[qq]C[Liu: got to attach and retreat in sente

Fan: that seems good for W. ]
;W[kq]
;B[kp]
;W[lr]C[Liu: this is certainly a bad exchange for W, but at least W has lived stably.

And the lower right corner is similar in terms of points. Though in the game, B is more solid if W enters on the right side.]))
(;B[or]
;W[qr]
;B[oq]
;W[ro]C[Tang: it seems like the wedge doesn't actually lose much here

]
(;B[qo]C[Tang: surely just capturing is unacceptable])
(;B[rn]C[and if you attach, then it is great for W.]
;W[qo]C[now the wedge loses nothing]))
(;B[qp]C[Fan: if you turn, then the wedge does become a losing exchange. But how is the result?]
;W[rr]
;B[rq]
;W[qr]C[Tang: well, originally it seemed like this is ridiculous for B.

Fan: yes, and in comparison, the wedge doesn't lose much.

Tang: actually, the wedge does lose quite a lot, but it feels like B loses more.

Liu: so  from the whole board perspective. B had so many stones in this area, and let W live so comfortably.]))
(;B[qp]C[Tang: now if you hane, it feels like W can say thank you for the gift!

Fan: B got tricked!]
;W[pp]
(;B[op]
;W[qo]
;B[rp]
;W[oq]
;B[pr]
;W[qn]
;B[rq]
;W[on]
;B[mp]
;W[pm]C[Tang: it seems unacceptable for B. W is quite thick with the ponnuki.])
(;AE[oo][po]C[without the exhange, B can ladder W]
;B[op]
;W[po]
;B[oo]C[The game is as if B ataried in the wrong direction

Liu: they didn't learn how to play the ladder correctly.])))
(;B[qo]
;W[qp]
;B[pp]
;W[oo]
;B[qn]
;W[qq]
;B[qr]
;W[rr]
;B[pr]
;W[ro]
;B[rn]
;W[op]C[Fan: just the simple turn

Liu: not playing any clever tricks]
;B[rs]
;W[rq]
;B[sp]
;W[kr]C[Tang: it hanes at S5

It seems like it can also choose not to exchange at S5.

I think S5 is merely a way to make less variations in the tree of moves. It probably only plays it because it thinks it is winning.

Liu: W has many moves in sente: P2, P3, and it can get P1 in sente too by throwing in at R1.

So W already has a stable shape]))
(;W[qq]C[so it thinks L4 is better placed]
;B[qp]
;W[pr]
;B[qr]
;W[rq]
;B[or]
;W[pp]
;B[oq]
;W[qo]
;B[op]
;W[po]
;B[oo]
;W[qn]
;B[pm]C[Fan: now the centre two stones are very valuable.

Tang: yes, it is a good moyo, and L4 is better than M3.

Liu: let's count this a bit.

over 50 points for W not counting the left side

Tang: over 60 for B ...

it is hard to say, as a move on the left is very big, but if you play on the left, then B gets the very big move at S2.]
;W[en]
;B[rr]
;W[rp]C[Tang: B can jump or turn. The turn is more thick.]
;B[qm]
;W[rn]
;B[gm]C[Liu: B can just sacrifice the stone.

Tang: W is definitely not satisfied.]))
(;B[lq]
;W[qq]C[It's probably as we said earlier: if B plays a two space, then when W lives in the corner, the position of M3 is bad.]))
(;W[ij]
(;B[ik]C[Tang: I suppose B plays to play here?]
;W[hi]
;B[hj]C[Tang: I had this shape in mind, but whether these moves are at all profitable, I can't say.])
(;B[hi]C[Fan: B planned to connect

Tang: but if it was connect, then. I don't quite understand it.

Fan: this is quite complicated locally.

Liu: W has several options locally]
;W[ik]C[Tang: W just needs to exchange, and it seems very difficult for B.

I did think about this, but I couldn't see how B had any profit.]
;B[gk]C[(alphago's move)

Tang: so it just fights directly! I didn't consider this. I thought that W was pretty solid.

B only has a measly approach stone (C6) to help run these stones out]
;W[gj]C[Fan: it isn't just trying to run with this stones. As W can capture them like this.]
;B[eo]C[Fan: maybe the centre aji helps the fight here.

Tang: wow... Though I considered extending in the centre, I couldn't imagine.

This sort of plan!

Originally if B just jumped at E6, I doubt that W would come out and fight

now, B sacrifices the centre stones just to get to play here. It seems (strange)

Liu: perhaps it doesn't just the centre exchanges as losing much.

Perhaps B lost 7-8 points or so but ...]
;W[]
;B[ki]C[here there is an atari]
;W[jf]C[Tang: W has to atari]
;B[jk]C[then it can press here

Tang: and B can seal off the right side by playing L13

Liu: perhaps it often plays moves whose value that isn't evident at a first glance. Or it is even sacrificing several stones.

But perhaps there is value in follow-ups that we can't see. That we have to taste for ourselves a bit.

Fan: and search for

It's sense of aji is often exquisite.

Liu: This reminds me of game 1 against Ke Jie

Fan: yes, the cut that was clearly gote.

Liu: not many points, and at first glance it seemed small, and a waste of a move. But it slowly proved it's value.])))
(;B[en]C[Liu: so as jumping now is a normal shape for pulling out the C6 stone, it thinks this is better for W than kicking

Fan: W's corner is more solid. Both sides have backed off a little.

W has used one move to fully shore up the corner. Though B's jump is faster, it hasn't completely connected either.

Tang: like this W will probably not crawl (F2)

Fan: yes, W saves a move
so B doesn't jump. and plays elsewhere.

Liu: so B treats the approach as a profitable exchange when W jumps.

Fan:
You often see this in alphago's games. It often plays a move on one part of the board, and then moves on to another part. And then gathers the scattered possibilities together.

Liu: a top level technique.]))
(;W[co]C[Tang: W will obviously kick]
;B[dn]
(;W[eo]C[Tang: then W kosumi

Liu: B probably has to play the knight's move to get out

Fan: I don't know the answer here because alphago wouldn't play this. It isn't in my dictionary.]
;B[fm]C[Liu: maybe because B is still threatening to run out at G11. There is a lot of aji.])
(;W[fr]C[alphago thinks W should crawl.

Tang: so, it's because it thinks it is hard to attack this B group?

Fan: I think it is something to do with follow up aji in the centre.

Tang: so just take go for the territory])))
(;AE[pn]AB[qn]
;B[]
;W[po])
(;B[oq]C[Tang: can B consider the bump here?

Liu: trying to both defend the corner and making it difficult for W to extend.

]
(;W[no]C[Fan: alphago would jump

Tang: against the bump, it is a good idea to play lightly.

If W has a way to play lightly out of this, then the bump may be bad.

as W is threatening to attach at Q5 and crosscut.

Fan: there are still problems locally.





])
(;W[np]C[Liu: so extending is too heavy]))
(;B[op]C[Tang: this is the other possibility to defend the corner])
(;B[lq]C[Tang: it seems like W profits here, it doesn't feel great.]
;W[qq]C[Liu: there are only two options normally here: Q4 or R4.]
(;B[pp]
;W[pr]C[this reverts to a 3-3 invasion of the star point, and W will live very comfortably]
;B[or]
(;W[qr]
;B[oq]
;W[ro]C[Fan: a very big corner

Liu: W is definitely very satisfied])
(;W[rr]C[Liu: W may also tiger to go one space further]
;B[ps]
;W[qr]
;B[oq]
;W[rn]))
(;B[qp]C[Liu: hane should be a stronger resistance]
;W[pr]
(;B[pp]C[Liu: this would revert to the 3-3 invasion

Fan: even worse, as B chose the wrong direction])
(;B[qr]C[Fan: forced

]
;W[rq]
;B[or]
;W[pp]
;B[oq]
;W[qo]
;B[op]
;W[po]
;B[oo]
;W[qn]C[Tang: B loses a lot of territory, and I think it isn't necessary better than just extending at Q4 in the first place.

Liu: B has haemorrhaged territory here. And particularly the M3 stone is awkwardly placed.]
;B[pm]
;AE[lq]AB[jn]C[Liu: if only the B stone was around K6!

Tang: now this might be playable]))))
(;W[]
;B[ki]C[Tang: perhaps here?

 now the scattered B stones still seem quite useful.

Liu: so the centre can turn from W influence to B influence

Tang: after just two moves, it does truly seem like that

My feeling was that W was better, but it's not necessarily valid.

It's a question of evaluate the strength and weakness in the centre.

Liu: W is not that thick in the centre.]
;AE[ki]
;W[jf]C[Liu: if W had a stone here, thinks would be completely different.])
(;W[dn]C[Liu: so for example, um, I'm not sure. Let's play a poor move.

What did alphago fear?

]
;B[pe]C[Fan: alphago would play]
;W[pd]
;B[qi]C[like Tang sensei said to sacrifice the corner]
;W[qc]
;B[ki]C[and like Tang sensei said again. His shape instinct is very good.]
;W[kh]
;B[lh]
;W[hi]
;B[ji]
;W[gh]
;B[nj]C[Tang: connecting both sides

Fan: making a pretty moyo

Liu: after these few moves, it really does feel like B is comfortable

Tang: it feels like once W plays the D6 jump, B is better!

In fact, I think that B could consider playing this directly with approaching at F3

why not play this directly as W certainly won't respond to F3.

Liu: if W responds, that is certainly ideal, but W won't.

Tang: I think that this is also a very big move.

Fan: actually at the time of F3, B did think that there were several moves such as L11, or Q15 which were all good, and comparable, and didn't have a definite opinion on which was best.

These 3 points are all very big.])
(;W[pj]C[Fan: actually, I suddenly had a thought - what if W grabs this big point first?

Liu: might you have overplayed?

...

so this move is wrong.]
;B[pi]C[Tang: maybe B will attach then, given that B has several sente moves

Fan: good move, good move

Liu: are you digging traps again?

Fan: hehe, trying to bury Tang sensei in a hole.

Well, if W plays here, B would also attach.

...

Fan: hence this is why alphago thinks that even though W has lost out, W has to defend now at Q15.

]
(;W[pe]C[only move]
;B[oj]C[it thinks this is good for B

Tang: certainly

Liu: of course

Fan: Tang sensei is truly very strong

Liu: very quick to find the shape.

Fan: in just a few seconds])
(;W[oj]C[Liu: what if W tries to resist?

is it really not possible?]
;B[qj]
;W[qk]
;B[pe]
;W[pd]
;B[oi]C[Liu: that's a strong move, are you not afraid I atari?]
;W[qi]
;B[rd]C[Fan: B has this good move

It is very difficult for W to respond

Liu: it seems like W already can't escape.]
;W[qg]C[Fan: what is the best order, R14 or R12?

Tang: atari first]
;B[qh]
;W[rj]
;B[qf]C[Fan: this should be completely unacceptable for W

Liu: as W played first here, and B not only saved the corner, but captured W's two stones.])))
(;B[ob]C[...

Tang: so I think there is no point to play this hane]
(;W[nb]C[...

Tang: if you hane I think I should have no problem living unconditionally

Liu: wait, but isn't there a problem with blocking at O18 as B can cut at Q15]
(;B[qb]C[Tang: there must be at least ko])
(;B[pe]
;W[pd]
;B[qb]
;W[rd]
;B[qc]
(;W[oa]
;B[qh]C[Liu: like this can't B sacrifice the corner?

Tang: wasn't B going to sacrifice the corner anyway?

Liu: but like this, isn't it uncomfortable for W to capture?])
(;W[qh]C[Tang: then in that case I'd probably play here

if you cut O17, I'll just let you live at the outside is bigger than the corner])))
(;W[pe]C[Liu: when you hane, can W pull back? solidly?

Tang: connecting seems ok. Actually it seems better as the outside is bigger.

Fan: if B tenukis now, is the corner unconditionally dead?]
(;B[nb]
;W[qb]C[there is still this move])
(;B[]
;W[nb]C[Tang: hane]
;B[na]C[Fan: might there be the double hane?

Liu: hehe

Tang: :)

Fan: just get some endgame!

Liu: how relentless!]
;W[pb]
;B[pa]
;W[qb]
;B[mb])))
(;B[ki]C[...

(see later discussion)

Fan: alphago thought these 3 moves were all very big])
(;B[pe]))
(;W[ii]C[Liu: because W has no way to defend all the ko threats with one move as E11 is still a threat]))
(;B[ha]C[Tang: so B can start the ko then]
;W[ba]
;B[jg]
;W[bf]C[Liu: W can capture here]
;B[ih]C[Tang: but if B captures an extra stone, then isn't it good for B?

oh! But W has spent one less move!

oh no, this is terrible.]
;W[nf]C[Fan: alphago would play here

Liu: it is W to play not B

Tang: B is a move behind, so don't consider this, no, no

hehe

Liu: Tang sensei has come to his senses again.]))
(;B[ad]C[Fan: what if B starts the ko now?


(initially Fan said that alphago played here, but Tang corrected him)]
;W[ac]
(;B[ca]
;W[ea]
;B[aa]
;W[cg]C[Liu: can I consider cutting as a threat?]
;B[bg]
;W[ba]
;B[hh]
;W[ch]C[Liu: is there the possibility of connecting?]
(;B[ig]C[if you capture,]
;W[af]C[W can end the ko here!])
(;B[aa]
;W[af]C[Liu: same principle as B has no threats])
(;B[af]C[Liu: so if B has to make life, then it is as if W already forced B to submit, so even if W loses the ko, W doesn't mind.

Tang: this seems unacceptable for B.]
;W[ig]))
(;B[hh]
;W[cg]C[Tang: if B plays A16 first, W can cut. I thought something was wrong.])))
(;W[gh]C[Tang: if W hanes, then ]
;B[hh]
;W[ig]C[and B can start the ko now as there is no way for W to remove all threats with one move]
;B[fa]
;W[ga]
;B[ad]
;W[ac]
;B[ca]
;W[ea]
;B[aa]
;W[gi]C[DH: my variation]
;B[ha]
;W[ba]
;B[jg]
;W[ih]
;B[aa]))
(;B[fa]C[Liu: firstly what if B starts the ko now?]
;W[ga]
;B[ad]
;W[ac]
;B[ca]
;W[ea]
;B[aa]
;W[gg]C[Liu: this is very difficult for B with no threats

Tang: B can start the ko, but B will still have to spend a move to live on the top.

Fan: W's outside is perfectly solid

if B starts this ko, B can't really lose it. as otherwise, B has spent two extra moves to start it.

Tang: no you didn't spend an extra move

Fan: but B spent a move on the inside and has to spend another move to start the ko

Tang: no, it is as if W spent a move to defend against the ko

Liu: and that B gained nothing from starting the ko.

Tang: all B gets is H19 in sente

Fan: but that move has no value

Liu: as B will still have to spend another move to live

Fan: my meaning is that in B exchanges a move at the top for the G13 move, and this exchange loses B too much, and B still lost the ko.

Liu: hence B has to create ko threats on the outside first.]))
(;W[ha]C[Liu: when you played it, I just suddenly had an idea

what if W hanes here first?

Fan: what is the meaning?

...

Fan: what can B do?

Tang: it's truly hard to respond]
(;B[ib]C[Tang: if you connect, W profits

Fan: oh, I see!]
;W[ie]
;B[hd]
;W[ke]C[B has less eyespace, and the ko is better than in the game])
(;B[ie]
;W[ib]C[this is even better for W than the game as B has less liberties])
(;B[ig]C[Tang: maybe there is this sort of move. B won't connect any more.

Fan: Tang sensei is truly strong!

Liu: so Fan sensei actually already prepared for this question!

Fan: alphago would also play here

Liu: you were just setting a trap for Tang!

Fan: well, and he didn't take long to find the solution!

Tang: you were trying to dig a hole for me! 

Fan: hehehe

_

Liu: this pushing move makes the H19 move bad as without the K18 for H19 exchange, B doesn't have enough liberties to push here]
(;W[ie]
;B[hd]
;W[jc]
;B[ic]
;W[ia]
;B[ga]
;W[fa]
;B[ja]C[W can't fill B's liberties]
(;W[kb]
;B[ih]C[Liu: B can just extend])
(;W[ke]
(;B[fg]C[Tang: and B can just kosumi and W is dead.

Fan: that is very clear

Tang: no, actually])
(;B[hh]C[B can just directly atari!

B has 4 liberties!

if B had 3 liberties, B has to kosumi])))
(;W[hd]C[Tang: wait, wait, somehow I have another question, what if W throws in?]
;B[hc]
;W[ie]
;B[ia]C[Tang: W can't connect.

well in that case it isn't great for W

it's a bit subtle

Liu: alpha sensei's moves are very solid. there won't be simple issues with them.

Fan: there aren't many flaws.]))))
(;B[ie]C[Liu: first instinct, W even let you escape, but instinct B goes back down.

]
;W[ib]C[Tang: so logically, B is afraid of this

Fan: then the corner is completely solid

Liu: W has a lot of territory

Tang: but B can still clamp K18, but for now, if B can't do anything in the centre, then B loses a lot of the territory

Fan: suddenly it seems like W has a lot of territory, especially after the corner exchanges. And B's shape is truly not very nice.

Tang: but this is still playable. The top is all your territory, but your centre shape isn't great either.])
(;B[ig]C[...

Liu: this doesn't work]
;W[ie]
;B[hd]
;W[jc]C[B is dead]))
(;W[he]C[Liu: if we play Tang's move now, is the issue that]
(;B[ie]C[B can push?]
;W[fe]
;B[ha]C[Liu: B can descend in sente

Tang: oh, yes, true

 no wait]
;W[if]C[hehe

if you descend, I can block and threaten to atari and capture!

Liu: oops, my blunder.])
(;B[ha]C[Liu: so B has to descend first?]
(;W[ga]C[Liu: W can't play here just to short B's liberties as then it becomes a direct ko

Fan: a direct ko would be too risky!])
(;W[ea]C[so W has to hane]
;B[ie]C[then like this, B can break out.

Tang: truly.

Liu: W falls apart on the outside

Tang: I didn't notice the descend.

Fan: that's a good move Liu!

Liu: well I didn't get it right the first time, and got KOed by Tang!])))
(;W[fe]C[Fan: W played here

Liu: didn't W hane?

Fan: oh sorry

Tang: the result is similar, actually no]
;B[ha]
;W[ea]
;B[if]C[Tang: not good for W]))
(;B[ca]
;W[ea]
;B[aa]
;W[ac]
;B[ad]))
(;W[ea]C[Liu: but why did W turn?

W could have killed B unconditionally like this.

Tang: no, it is seki after B19.

Liu: well this is the safest way for W to play then

Instead, W purposefully allowed a one step ko. Why?

Can we explain this?

]
;B[dh]C[Liu: in this case, B will probably respond here, and G18 and G19 are both absolute sente, which helps the other group.

so if both groups can settle, then can we say it is a success for B?

Tang: hmm, reasonably successful

the centre white stones will be in trouble

Liu: and now perhaps I understand why B make the exchanges in the corner first before extending.]))
(;B[dh]C[Liu: if B extends directly, then]
;W[he]C[it is probably afraid of this]
(;B[ie]
;W[fe]C[Tang: B is in trouble

Liu: before, if B exchanged all the moves in the corner, B would have G17 and G18 in sente, so B can just break out at K14

but now, B can't deal with the cut.]
;B[db]
;W[ec]
;B[cb]C[Liu: This is no longer sente]
;W[cc]C[Tang: even if B responds, it is difficult for B]
;B[eb]
;W[fc]
;B[gc]
;W[gb]C[Tang: this was the purpose of the G18 turn

B is still in trouble])
(;B[fe]C[Tang: so it seems like this is the only move]
;W[hf]C[Liu: but W can press E12 and E11 in sente, so B seems to be in trouble.

Tang: B is going to die

Fan: this is complicated. in alphago's data:]
;B[gg]
;W[eh]
;B[di]
;W[ei]
;B[dj]
;W[hd]C[Liu: Fan sensei mentioned this variation

Tang: oh, just pushing here. Not trying to kill everything

Liu: Fan told me earlier that B was afraid of this

Fan: even in the variation, it isn't necessarily unplayable, but it just thinks the game is better for B.

Liu: the J16 and K16 moves lose a lot]
;AE[kc][id][jd][je]C[Liu:])))
(;B[he]C[Fan: what if the normal hane?

Tang: it must think B falls into a trap]
;W[gf]C[Liu: just extend and it seems difficult for B?

Fan: that is that the H16 cut and the E12 net are miai

Liu: the hane helps W get think

and W has a lot of sente moves against the left B group such as G14.

so B needs to be clever when handling the 3 stones, and simple moves will give B a difficult situation.]))
(;W[cb]C[Liu: yes, in the self-play, it was like this]))
(;W[cd]C[Tang: why not block directly? What is the point of the jump

Liu: this is a very good question, I was also wondering]
;B[bd]
;W[bc]
;B[be]
;W[fb]C[Liu: so perhaps it is the same idea again, that the jump makes B heavier?

]
;B[di]C[with my poor skill, perhaps a move to exchange?

Tang: poor skill! From someone with a 100% record against Ke Jie!

...

Tang: yes it's true, perhaps if B can get a few moves here, B could play F13 and consider sacrificing the two F16 stones.

maybe that's why]))
(;AE[ci][pn]C[Tang: I think kicking first is a human move too, but more common in this shape]
;W[kd]C[this is the most common move

Fan: played in the Wuzhen pairgo match]
;B[ed]
(;W[fc]C[alphago played here!

...

Fan: it was my first time seeing this move too

Tang: but in that game, I thought W wasn't very good

Fan: alphago thought it was even]
(;B[ne]C[but that B should have first played here])
(;B[ec]
;W[eb]
;B[dd]C[in the real game]
;W[cc]
;B[db]))
(;W[ec]C[but humans play here]
;B[fd]
;W[gc]
;B[gd]
;W[hc]
;B[hd]
;W[ic]
;B[cn]C[Liu: so this is the purpose of the Q17 kick, to press white low

Fan: you mean the Q17 exchange is profitable

Tang: it is that if you don't kick, then W won't extend at L16. As kicking makes W heavier, so W owes a move.]))
(;W[cd]C[Liu: so what if W still tries to tenuki?

Fan: I did check this one]
;B[lc]C[this pincer]
;W[me]
;B[jd]C[this sort of direction

Tang: the two space low pincer looks a bit strange]
;W[hc]C[Tang: first instinct is that W is also ok

Fan: alphago did also think C16 was a move to consider, a normal move too.

Liu: so this is also an acceptable result. It isn't like we often think that there is only one possibility

Fan: it isn't that in this situation, it thinks there is only one move, for example ...])
(;W[hd]C[Fan: it might also say this move is ok])
(;W[ld]C[or this move too

these are move it was considering. ]))
(;B[pf]C[Liu: in many alphago games, we have often seen the keima directly.

]
;W[cd]C[...

Liu: so we have an explanation now:

if B keimas immediately, W will probably tenuki]
;B[pc]
;W[jc]C[and W will no longer respond

so the intent of the Q17 kick is to make W heavy.]))
