This 'n' that

[Bill Spight]

AlphaGo vs. AlphaGo Game 4

$$Bcm11 Mini-Chinese?
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Click Here To Show Diagram Code

[go]$$Bcm11 Mini-Chinese?
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$$ ---------------------------------------[/go]

Of course not. makes a kind of Mini-Chinese shape. This is, I think, another AlphaGo innovation, but it would not have appeared strange to the players of two centuries ago. Not only did they play the Mini-Chinese in handicap games, they often played extensions in the opening that are wider than the extensions to make a base. I expect that AlphaGo is reviving that style of play.

There are 5 hits of the left side shape in waltheri, the oldest being Rin Kanketsu in 2010 and 4 in 2015 (other corners were usually black top right but not 4-4 and white bottom right).

Thanks. I guess I flubbed the lit review.

Making further extensions from the top left joseki when you have the corner beyond seems fairly standard to me, in fact I remember learning from some book (maybe [sl=ADictionaryOfModernFusekiTheKoreanStyle]A Dictionary Of Modern Fuseki, The Korean Style[/sl]) that if you do the hanging connection and normal joseki extension it's inefficient with a 4-4 below (I recall playing as white against this on OGS and got a good result):

$$Bcm11 Joseki inefficient (4-4 not helped enough)
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Click Here To Show Diagram Code

[go]$$Bcm11 Joseki inefficient (4-4 not helped enough)
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So play a move which helps the corner too, and if white invades on the left around a you can jump out around b.

$$Bcm11 Better balance
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Click Here To Show Diagram Code

[go]$$Bcm11 Better balance
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$$ ---------------------------------------[/go]

Very interesting. Thanks.

So anticipating this fight, in which black's hanging connection group is fairly flexible and can run out nicely, white may peep first, trying to make it heavier and less easy to jump out (on this half board on waltheri it has 68 games and 54.5% win, vs 89 games with 49.5% win for the one-space extension: not hugely significant but a valuable hint I think):

$$Wcm10 White's counter
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Click Here To Show Diagram Code

[go]$$Wcm10 White's counter
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$$Wcm10 Black's reply?
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Click Here To Show Diagram Code

[go]$$Wcm10 Black's reply?
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$$ ---------------------------------------[/go]

Looking at the whole board, OC.

[Bill Spight]

Bill

Interesting thoughts! First, just parenthetically, omitting D10 has been tried by humans before (Takagawa, Kobayashi, etc), but is admittedly rare.

Ah! Thanks.

Your most intriguing comments are about using "light" in a new sense. I likewise have come to the conclusion that we need to re-invent the vocabulary somewhat to start making sense of AlphaGo's plays.

Yes, it does broaden the definition a bit. But I think that it is close to Rin Kaiho's understanding. In something I read long ago he said that keeping your options open (and generating options) is light play.

The best approach we have both adopted seems to be to say it's just like Go Seigen (and it's fascinating and exciting that Yoda's forthcoming book on AG will focus on its similarities with Go and Dosaku). I think that means a lot to us and anyone else who has been through the corpus of Go's games, but it's very hard to be specific or to generalize.

I, like everybody else, I suppose, have found many of AlphaGo's plays surprising. But I don't find them alien or otherworldly. It's opening play, especially, reminds me of Go Seigen. I am also in general reminded of go of a few centuries ago, and of Kitani. I missed the specific Dosaku connection, though. I think that Yoda's book will be quite interesting.

Rather than the light/not-heavy focus you have been taking, I have been thinking on other lines which may well end up at the same place. My thoughts have focused on thickness, which I think has been the dominant theoretical theme in pro talk for close to a century now. I'm sensing that AG seems to eschew that and to focus rather on influence (from which thickness may develop, but that's by the by as far as AG is concerned).

However, AG seems to focus on influence in a quite different way from us.

Yes. Looking at AlphaGo vs. human pro play, I have been impressed at how differently AlphaGo treats influence, and how much better. It seems like it utilizes it better and nullifies it better. As Brady Daniels says, "AlphaGo: Whatever you do is wrong." ( forum/viewtopic.php?f=10&t=13956 )

AG, however, seems to see things more nebulously, in terms of an influence map. Rather than a wall and its shadow it sees a lake. Its focus is outwards. It seems to be able to see what effect outside stones will have elsewhere over a much wider area than humans do. What AG seems to be doing is what humans tried to analyse at the time of Shin Fuseki (e.g. the way they talked about the 5-5 point or tengen). The humans gave up because it was just computationally too hard, but at least they knew where to look!

My sense is that what I am saying does resolve into your thoughts on lightness. I know you've done some work on influence maps as well. Maybe we should revisit this? I feel sure even at this stage that we do need some new terminology, maybe based on influence maps. I'm attracted by the idea of basing it on water. Not just lakes, but fluidity, the notion of water being light and heavy, evaporating, freezing, mixing, diluting, etc. etc. Instead of food for thought, liquid for thought (Mine's a double, neat, thank you.)

Well, there are problems with influence maps, which is one reason that, after four decades of research, go programmers never approached consensus on an evaluation function. AlphaGo's value network has to be an improvement on them, but, as moha indicates, it still needs to be supplemented by Monte Carlo rollouts.

I like your water metaphor.

As for humans, I think that the next generation will have a much better feel for the whole board than ever. Humans are very good at picking up things that they are unable to articulate.

[gowan]

In an earlier post in this thread Bill Spight commented on this move B15:

$$Bcm15 Close approach
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Click Here To Show Diagram Code

[go]$$Bcm15 Close approach
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$$ | . . . , . . . . . , . . X O . O b . . |
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$$ ---------------------------------------[/go]

asking who would have guessed this move. I think Go Seigen might have guessed it. It plays first in one of Go Seigen's six regions, as do his far approach moves and shoulder hits.

[jeromie]

I'm really enjoying your latest series of posts, Bill. Thanks!

(Thanks also to those engaging in conversation. I appreciate those contributions, too. )

[John Fairbairn]

Bill

Well, there are problems with influence maps, which is one reason that, after four decades of research, go programmers never approached consensus on an evaluation function. AlphaGo's value network has to be an improvement on them, but, as moha indicates, it still needs to be supplemented by Monte Carlo rollouts.

I've been wondering about rollouts in a tangential way.

Assuming I've understood how the whole thing works, I think it's not contentious to say that both humans and AG rely on intuition/neural networks. The result for AG is a bank of candidate moves which it considers further by means of rollouts (i.e. looks deeper tactically). Superficially humans do the same, but amateurs, especially in quick games, don't really come up with a list of candidate moves most of the time. Instead, assuming there are features they recognise, they come up with the "shape move" - a single move that they play as a knee-jerk response. There is often no deeper search, and when there is, it is simply of the type "is this safe?" as opposed to "is this candidate move better than that candidate move."

Now we mustn't assume pros play like that, but, if we assume there is a continuum from weak amateurs up to AG that expresses how much candidate moves are explored, can we really assume pros are right at the AG end?

Very many pros, and almost all those who have played AG, are now used to playing fast games. Have they got into the habit of not exploring candidate moves sufficiently? I'm quite sure they look very deeply at certain moves (conceivably even deeper than AG), but are they working with a much shorter list of candidates than AG and, if so, is this because they are too used to playing too quickly? They are Paganinis instead of Mozarts and Beethovens?

My thoughts, obviously still in flux, are heavily influenced by the fact that I am still transcribing 1930s games and I am regularly astounded at how much the style of play (almost everyone's - not just Go Seigen's) then resembles AG. Incidentally, I imagine very, very few modern players, even top pros, will have seen these games, beyond those of Go and Kitani. Almost all the games are commented by both players, and a distinctive feature of the commentaries is how often alternative moves (candidates) were considered. Apart from style, and of course lack of komi, the most distinctive difference between these games and modern ones is time. Time limits then varied between 16 hours and 8 hours. Call it 10 hours each on average, which works out about 5 minutes a move. That means 10 times longer than the ubiquitous 30 seconds a move of today, and ridiculously more than the 10 minutes each mode. Surely with that sort of difference it has to be a different kind of go - better even, as AG might be suggesting? Haute cuisine over fast food?

[moha]

I think it's not contentious to say that both humans and AG rely on intuition/neural networks. The result for AG is a bank of candidate moves which it considers further by means of rollouts (i.e. looks deeper tactically). Superficially humans do the same, but amateurs, especially in quick games, don't really come up with a list of candidate moves most of the time. Instead, assuming there are features they recognise, they come up with the "shape move" - a single move that they play as a knee-jerk response. There is often no deeper search, and when there is, it is simply of the type "is this safe?" as opposed to "is this candidate move better than that candidate move."

Now we mustn't assume pros play like that, but, if we assume there is a continuum from weak amateurs up to AG that expresses how much candidate moves are explored, can we really assume pros are right at the AG end?

Very many pros, and almost all those who have played AG, are now used to playing fast games. Have they got into the habit of not exploring candidate moves sufficiently? I'm quite sure they look very deeply at certain moves (conceivably even deeper than AG), but are they working with a much shorter list of candidates than AG and, if so, is this because they are too used to playing too quickly?

I think humans can never explore candidate moves sufficiently, errors/oversights will always happen. This is why shape and strategy were born - dealing with the uncertainity (unread lines) is the essence. But pro levels are different, real strength needs deep reading. I think there are two reasons for less candidate moves: humans minimax slower, but can choose candidates better. Still human pros rely on strategy for evaluating positions where the reading stops, which corresponds to Alphago's value network.

Alphago is yet different, however. It's search has two levels. For the upper nodes they use their policy net to choose good candidate moves to explore, and they do their search methodically. This, as you noted, is similar to human play. But the lower nodes - the rollout part - is unique. Rollouts explore to the end, use no evaluation function so are free from strategic beliefs, and only informative as a winning percentage. If you can give a position to a room full of pros, have them play games starting from that point, and after a few days ask how many of the games were won by black, that's good information.

The problem with this is that neural nets are so slow that AG cannot use it's real policy net during rollouts. They use a much reduced version, which means much weaker candidates are used during that phase. This is a major blow for MC which depends on the quality of moves during rollouts (room of pros vs room of beginners). Even with this huge handicap, rollouts are something that humans don't have, and can be more informative than intuition / value nets.

[John Fairbairn]

(Thanks, moha.)

I have several times mentioned AG's play being prefigured in the 1930s. I came across another good example this morning. The first 100 moves are below with my comments attached. We tend to talk about Shin Fuseki, but I think it's important to remember that the new thinking went much deeper than the fuseki alone. In any case, this was 1936, a few years after the Shin Fuseki proper, and its new ideas had had time to deepen.

(;SZ[19]FF[3]
PW[Maeda Nobuaki]
WR[6d]
PB[Shimamura Toshihiro]
BR[4d]
EV[Oteai]
DT[1936]
TM[11h]
KM[0]
RE[B+5]
US[GoGoD95]
;B[qd];W[nd];B[ne];W[pd];B[pe];W[oe];B[of];W[od];B[qe];W[qc];B[md];W[mc]
;B[me];W[lc];B[rc];W[pb];B[qb];W[pc];B[rb];W[ic];B[pk];W[fp];B[de];W[cp]
;B[pp];W[dc];B[cc];W[dj];B[ch];W[cd];B[dd];W[bc];B[cb];W[bb];B[db];W[ec]
;B[bd];W[ce];B[be];W[cf];B[bf];W[df];B[eb];W[fc];B[cg];W[oo];B[op];W[no]
;B[np];W[mo];B[mp];W[lo];B[lp];W[ko];B[qn];W[oj];B[pj];W[ba];B[dk];W[cj]
;B[ej];W[ef];B[fb];W[gb];B[ck];W[oh];B[pg];W[kp];B[cn];W[kr];B[ok];W[cm]
;B[dm];W[bm];B[bj];W[dn];B[eq];W[fq];B[cq];W[dp];B[bp];W[bo];B[dq];W[bq]
;B[br];W[ap];B[fr];W[gr];B[fs];W[bs];B[hr];W[hq];B[ar];W[ds];B[cr];W[gs]
;B[er];W[or];B[qr];W[mr]
)

20: This is, in itself, not Shin Fuseki, perhaps. I was surprised by this move and even more surprised to see it had no comment (there was plenty of comment on the joseki just before). My conclusion was that it's an ijime-preventing move (see an earlier thread on this topic) as White's shape with a Black stone around 20 is uncomfortably exposed to a placement at O18, but it's also surprisingly effective at remotely controlling the upper left corner (reduces Black's options at the very least). But, overall, the main instantaneous impression is that Black's outside wall plus a bit of territory looks far superior given they have played an equal number of stones. However, AG-like, White has sensed that Black's thickness is not all that thick.

21: And Black maybe agrees, feeling obliged to take the side rather than a corner.

24: AG's favourite shimari - not so unusual in those days and often played in the more usual order.

26: Again uncommented! Looks low, but we've seen AG play unusually low moves.

46: Definitely an AG shoulder hit!

54: Giving up territory on the 4th line, supposedly bad in itself, but even if you assume White senses compensation in the centre, you have to admit that in this position he must have a touch of extra-sensory perception. As per my argument above, one factor must be that each player had 11 hours thinking time. At a more mundane level, however, it was also meant as a ladder breaker, as Maeda explains in his comments. He added that it was actually a misread and a very bad move - not because of what happened in the lower right, or the ladder, but because of the complex tactics/aji in the upper left.

56: Another shoulder hit.

59: A surprising attachment, certainly reminiscent of Go Seigen, and maybe of AG. But not commented, so maybe it was superobvious to a pro.

90: Maeda was known as the God Of TsumeGo, and this pattern belongs to the standard comb formation shapes (typically is a ko). But he confessed he overlooked Black 91. Would AG overlook this sort of early move, do you think?

100: An interesting tewari question: can we assume some of the stones in Black's baguette are now inefficient?

Black won the game by 5 but, as there was no komi, perhaps we can say it was even stevens and White's AG-like play did work.

[EdLee]

Hi Bill,

(Off topic):

100: An interesting tewari question: can we assume some of the stones in Black's baguette are now inefficient?

For some time now I've wondered about the limitations of tewari.
Happy to find out you've written about it -- HowToLieWithTewari.

[Bill Spight]

Hi Bill,

(Off topic):

100: An interesting tewari question: can we assume some of the stones in Black's baguette are now inefficient?

For some time now I've wondered about the limitations of tewari.
Happy to find out you've written about it -- HowToLieWithTewari.

Actually, How to Lie with Tewari is Charles Matthews' brainchild.

As for John's question, I don't think that the effects of the "baguette" are obvious at this point. After all, at the end of the game each stone exerts less than 1 pt. of influence. It is then hard to tell, maybe impossible, what their influence was earlier.

[EdLee]

Hi Bill, I meant that you contributed to that page.

[Bill Spight]

AlphaGo vs AlphaGo Game 33

$$Bcm11 Pincer
$$ ---------------------------------------
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . O . O . . . . . . . . . . . . . |
$$ | . . O , . . . . . , . . . . . X . . . |
$$ | . . O B . . . . . . . . . . . . . . . |
$$ | . . B B . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . , . . . . . , . . . . . , . . . |
$$ | . . . 2 . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . 1 . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . O . . . . . , . . . . . , . . . |
$$ | . . . . . a . . . . . . . . . X . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ ---------------------------------------

Click Here To Show Diagram Code

[go]$$Bcm11 Pincer
$$ ---------------------------------------
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . O . O . . . . . . . . . . . . . |
$$ | . . O , . . . . . , . . . . . X . . . |
$$ | . . O B . . . . . . . . . . . . . . . |
$$ | . . B B . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . , . . . . . , . . . . . , . . . |
$$ | . . . 2 . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . 1 . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . O . . . . . , . . . . . , . . . |
$$ | . . . . . a . . . . . . . . . X . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ ---------------------------------------[/go]

Instead of replying at "a" White plays a two space high pincer. This play also aims at the stones. I like it.

$$Bcm13 Go Seigen style
$$ ---------------------------------------
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . O . O . . . . . . . . . . . . . |
$$ | . . O , . . . . . , . . . . . X . . . |
$$ | . . O X . . . . . . . . . . . . . . . |
$$ | . . X X . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . , . . . . . , . . . . . , . . . |
$$ | . . . O . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . X . 2 . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . O . . . . . , . . . . . , . . . |
$$ | . . . . . 1 . . . . . . . . . X . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ ---------------------------------------

Click Here To Show Diagram Code

[go]$$Bcm13 Go Seigen style
$$ ---------------------------------------
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . O . O . . . . . . . . . . . . . |
$$ | . . O , . . . . . , . . . . . X . . . |
$$ | . . O X . . . . . . . . . . . . . . . |
$$ | . . X X . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . , . . . . . , . . . . . , . . . |
$$ | . . . O . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . X . 2 . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . O . . . . . , . . . . . , . . . |
$$ | . . . . . 1 . . . . . . . . . X . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ ---------------------------------------[/go]

Black plays a double approach, and White replies with a capping play, Go Seigen style.

$$Bcm15 Even steven
$$ ---------------------------------------
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . O . O . . . . . . . . . . . . . |
$$ | . . O , . . . . . , . . . . . X . . . |
$$ | . . O B . . . . . . . . . . . . . . . |
$$ | . . B B . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . 5 7 9 . . . . , . . . . . , . . . |
$$ | . . 6 O 8 . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . X . O . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . 2 O 4 . . . . , . . . . . , . . . |
$$ | . . 1 3 . X . . . . . . . . . X . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ ---------------------------------------

Click Here To Show Diagram Code

[go]$$Bcm15 Even steven
$$ ---------------------------------------
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . O . O . . . . . . . . . . . . . |
$$ | . . O , . . . . . , . . . . . X . . . |
$$ | . . O B . . . . . . . . . . . . . . . |
$$ | . . B B . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . 5 7 9 . . . . , . . . . . , . . . |
$$ | . . 6 O 8 . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . X . O . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . 2 O 4 . . . . , . . . . . , . . . |
$$ | . . 1 3 . X . . . . . . . . . X . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ ---------------------------------------[/go]

Black jumps into the corner and then extends from the stones to divide the left half of the board equitably.

$$Wcm24 AlphaGo special
$$ ---------------------------------------
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . 9 . . . . . |
$$ | . . . O . O . . . . . . . 6 7 5 3 . . |
$$ | . . O , . . . . . , . . . . 8 X 4 . . |
$$ | . . O X . . . . . . . . . . . . . . . |
$$ | . . X X . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . X X X . . . . , . . . . . , . . . |
$$ | . . O O O . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . 2 . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . X . O . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . 1 . . |
$$ | . . O O O . . . . , . . . . . , 0 . . |
$$ | . . X X . X . . . . . . . . . X . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ ---------------------------------------

Click Here To Show Diagram Code

[go]$$Wcm24 AlphaGo special
$$ ---------------------------------------
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . 9 . . . . . |
$$ | . . . O . O . . . . . . . 6 7 5 3 . . |
$$ | . . O , . . . . . , . . . . 8 X 4 . . |
$$ | . . O X . . . . . . . . . . . . . . . |
$$ | . . X X . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . X X X . . . . , . . . . . , . . . |
$$ | . . O O O . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . 2 . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . X . O . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . 1 . . |
$$ | . . O O O . . . . , . . . . . , 0 . . |
$$ | . . X X . X . . . . . . . . . X . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ ---------------------------------------[/go]

approaches the bottom left corner and Black plays a two space high pincer. Then jumps into the top right corner, AlphaGo style. Black takes sente and plays the kick against .

$$Wcm34 The fighting begins
$$ ---------------------------------------
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . 3 O . . . . . |
$$ | . . . O . O . . . . . 4 2 X O O O . . |
$$ | . . O , . . . . . , . . . 1 X X X . . |
$$ | . . O X . . . . . . . 6 . 5 . . . . . |
$$ | . . X X . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . X X X . . . . , . . . . . , . . . |
$$ | . . O O O . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . X . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . X . O . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . O . . |
$$ | . . O O O . . . . , . . . . . , X . . |
$$ | . . X X . X . . . . . . . . . X . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ ---------------------------------------

Click Here To Show Diagram Code

[go]$$Wcm34 The fighting begins
$$ ---------------------------------------
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . 3 O . . . . . |
$$ | . . . O . O . . . . . 4 2 X O O O . . |
$$ | . . O , . . . . . , . . . 1 X X X . . |
$$ | . . O X . . . . . . . 6 . 5 . . . . . |
$$ | . . X X . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . X X X . . . . , . . . . . , . . . |
$$ | . . O O O . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . X . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . X . O . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . O . . |
$$ | . . O O O . . . . , . . . . . , X . . |
$$ | . . X X . X . . . . . . . . . X . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ ---------------------------------------[/go]

With the atari, :W34:, the fight begins in earnest.

Before, I have shown you AlphaGo innovations, but this opening, while not exactly conventional, is well within the realm of human play, up until the 3-3 invasion. And now, OC, humans are playing that. Why show something so ordinary?

Well, it shows a different way that AlphaGo handles the left side, and it is also a prelude to the quiz in my next note.

[Bill Spight]

Human or AlphaGo?

The next diagrams come from the AlphaGo (Master) vs. human games this past winter. They all show pincers. The question is, who played the pincer, AlphaGo or human?

$$Bcm7 Three space high pincer
$$ ---------------------------------------
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . O . . . . . . . . . . O . . . . |
$$ | . . . , . . . . . , 1 . . . . , X . . |
$$ | . . X . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . , . . . . . , . . . . . , . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . O . . . . . , . . . . . X . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ ---------------------------------------

Click Here To Show Diagram Code

[go]$$Bcm7 Three space high pincer
$$ ---------------------------------------
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . O . . . . . . . . . . O . . . . |
$$ | . . . , . . . . . , 1 . . . . , X . . |
$$ | . . X . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . , . . . . . , . . . . . , . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . O . . . . . , . . . . . X . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ ---------------------------------------[/go]

Who played the pincer, AlphaGo or human?

The human. This is from game 11 on Dec. 30. I don't have a name for the human player.

$$Bcm9 Two space high pincer
$$ ---------------------------------------
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . X . . . . . . . . . . . . . . . |
$$ | . . . , . . . . . , . 1 . . O , X . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . X . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . , . . . . . , . . . . . , . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . X . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . O . . . . . , . . . . . O . . . |
$$ | . . . . . O . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ ---------------------------------------

Click Here To Show Diagram Code

[go]$$Bcm9 Two space high pincer
$$ ---------------------------------------
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . X . . . . . . . . . . . . . . . |
$$ | . . . , . . . . . , . 1 . . O , X . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . X . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . , . . . . . , . . . . . , . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . X . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . O . . . . . , . . . . . O . . . |
$$ | . . . . . O . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ ---------------------------------------[/go]

Who played the pincer, AlphaGo or human?

The human, Kim Jiseok, 9p. This is from game 41 on Jan. 2.

$$Bcm9 Two space high pincer
$$ ---------------------------------------
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . X . . . . . . . . . . . . . . |
$$ | . . O , . . . . . , . . . . . X . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . , . . . . . , . . . . . , . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . O . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . O . . . . . , . 1 . . . , X . . |
$$ | . . . . . X . . . . . . . . O . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ ---------------------------------------

Click Here To Show Diagram Code

[go]$$Bcm9 Two space high pincer
$$ ---------------------------------------
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . X . . . . . . . . . . . . . . |
$$ | . . O , . . . . . , . . . . . X . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . , . . . . . , . . . . . , . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . O . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . O . . . . . , . 1 . . . , X . . |
$$ | . . . . . X . . . . . . . . O . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ ---------------------------------------[/go]

Who played the pincer, AlphaGo or human?

AlphaGo. This is from game 47 on Jan. 3, vs. Tan Xiao, 7p.

$$Bcm7 Two space high pincer
$$ ---------------------------------------
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . O . . . . . , . . . . . X . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . , . . . . . , . . . . . , . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . X . . . . . . . . . . . . . . . . |
$$ | . . . , . . . . . , . 1 . . . , X . . |
$$ | . . . O . . . . . . . . . . O . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ ---------------------------------------

Click Here To Show Diagram Code

[go]$$Bcm7 Two space high pincer
$$ ---------------------------------------
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . O . . . . . , . . . . . X . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . , . . . . . , . . . . . , . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . X . . . . . . . . . . . . . . . . |
$$ | . . . , . . . . . , . 1 . . . , X . . |
$$ | . . . O . . . . . . . . . . O . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ ---------------------------------------[/go]

Who played the pincer, AlphaGo or human?

The human, Ke Jie, 9p. This is from game 19 on Dec. 30.

$$Bcm13 Two space pincer
$$ ---------------------------------------
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . O . . . . . . . O . . . . . |
$$ | . . . O . . . . . , . . . . . X . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . X . . . . . . . . . . . . X . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . O . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . , . . . . . , . . . . . , . . . |
$$ | . . . . . . . . . . . . . . . . O . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . X . . . . . . . . . . . . . . . . |
$$ | . . . , . . . . . , . . . . . , X . . |
$$ | . . . O . . 1 . . . . . . X . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ ---------------------------------------

Click Here To Show Diagram Code

[go]$$Bcm13 Two space pincer
$$ ---------------------------------------
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . O . . . . . . . O . . . . . |
$$ | . . . O . . . . . , . . . . . X . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . X . . . . . . . . . . . . X . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . O . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . , . . . . . , . . . . . , . . . |
$$ | . . . . . . . . . . . . . . . . O . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . X . . . . . . . . . . . . . . . . |
$$ | . . . , . . . . . , . . . . . , X . . |
$$ | . . . O . . 1 . . . . . . X . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ ---------------------------------------[/go]

Who played the pincer, AlphaGo or human?

AlphaGo. This is from game 54 on Jan. 4, vs, Nie Weiping.

$$Bcm7 One space high pincer
$$ ---------------------------------------
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . O . . . . . , . . . . . X . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . , . . . . . , . . . . . , . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . X . . . . . . . . . . . . . . . . |
$$ | . . . , . . . . . , . . 1 . . , X . . |
$$ | . . . O . . . . . . . . . . O . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ ---------------------------------------

Click Here To Show Diagram Code

[go]$$Bcm7 One space high pincer
$$ ---------------------------------------
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . O . . . . . , . . . . . X . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . , . . . . . , . . . . . , . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . X . . . . . . . . . . . . . . . . |
$$ | . . . , . . . . . , . . 1 . . , X . . |
$$ | . . . O . . . . . . . . . . O . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ ---------------------------------------[/go]

Who played the pincer, AlphaGo or human?

The human, Chen Yaoye, 9p. This is from game 21 on Dec. 31.

How did you do? The answers were far from obvious, I know. Did the enclosure in the top left corner fool you?

But I noticed, when going over the AlphaGo vs. AlphaGo games, that AlphaGo does not play pincers very much, except double approaches to the 4-4, which I don't really think of as pincers. Unless it had already bolstered one side of the pincer. For instance, if it had responded to an approach with a keima; then it readily played a pincer against the approach stone. A look at waltheri suggested that humans play unbolstered pincers 20-30% of the time. It seemed like AlphaGo played them much less often.

I ran through the 50 self play games and found that AlphaGo had played an unbolstered pincer against itself in 12 of the games, 24%. That meant that it probably played unbolstered pincers less than 10% of the time. OTOH, it played a lot of 3-3 invasions, which you cannot pincer. So maybe it just did not have as many opportunities to pincer as humans. Fortunately, I had a direct comparison in the 50 human vs. Master games. Also, AlphaGo might pincer humans more often than itself, given the differences in play. And AlphaGo would play the 3-3 invasions against humans, as well.

AlphaGo played unbolstered pincers against itself in 12 of the 50 AlphaGo vs. human games, while humans played unbolstered pincers against AlphaGo in 22 games. Two games overlapped, as each side played an unbolstered pincer. That's pretty good evidence.

The question now is in what kind of positions do humans play the unbolstered pincer but AlphaGo does not? That's not an easy question to answer, and there is not much evidence to go on. Hence my little quiz. What do you think is the difference?

[John Fairbairn]

The question now is in what kind of positions do humans play the unbolstered pincer but AlphaGo does not? That's not an easy question to answer, and there is not much evidence to go on.

A fascinating insight, Bill. I have not seen the instructive bolstered/unbolstered paradigm in this form before, but a relative reluctance to play pincers was a feature of Shin Fuseki. There, however, I think the usual explanation is that there were more high positions (and so maybe more emphasis on large moyos) which offered fewer opportunities for pincering.

But the later Go Seigen offers a closer parallel, and maybe also some strong evidence for your hypothesis. You see, for example, a marked reluctance to pincer in his games with Fujisawa Kuranosuke. My intuition is that it applies elsewhere, but I'm more familiar with those games as I did a bog book on their matches.

For example:

(;AB[pd][pp][de]AW[dc][dq][cn]TR[cn]LB[ce:A][ee:B][cg:C][dh:D]SZ[19])

Here Go opted for the triangled move even though in his commentary he noted that White had options at A and B and also pincers such as C and D (in that order, if that's significant). A different commentator added that tenuki in the upper left to play the slow shimari was very rare at that time (1951) but it had since gradually become common as komi go took over. So Go felt it was better even in no-komi times.

(;AB[qd][od][pq][qp][ce][co]AW[dc][qn][qk][dq][dh][cl]TR[cl]SZ[19])

Here, Go played a "neutral" pincer in the upper left first, but clearly with a view to bolstering the pincer in the lower left (triangle). He goes into some depth, with long variations, about the possible subsequent play in the lower left, but a key factor in that, as he says, is the presence of the first pincer stone above.

In a later game he played the high pincer in the lower left instead, clearly to avoid any preparation by Fujisawa. Even later, Fujisawa took measures to avoid the double pincer,

(;AB[pd][jq][fq][fp][ep][ic][pp][qo]AW[cp][dq][eq][do][dc][ce][qn]TR[qo]SZ[19])

Here Go was Black and played the triangle stone rather than the inviting double-wing forming pincer. He remarked that "not many other people would play this" and he famously followed it up with an empty triangle.

(;AB[pd][pp][dd][de][df][eh][ec][fc][qf]AW[dq][dc][cd][cb][eb][ce][cg][nc]TR[qf]
LB[kd:A][pb:B][lc:C]SZ[19])

In this case it was Fujisawa who baulked at the immediate pincer. He was, however, expecting to get a pincer (in order to build thickness, he said) but Go forestalled him with A. Fujisawa had been counting on White B, Black C. There were, however, other cases where Fujisawa (at a time when these were the only two 9-dans) clearly shared a preference to avoid or delay a pincer, but not to the same degree as Go.

(;AB[pq][pd][pf][de][pr][rl][or][nr][rp][qo][rn][sp][qp][rm][pn][on][no][ol][sr]
[lm]AW[po][qr][rq][op][so][qn][dp][qq][qm][ql][qk][pi][dc][kp][mp][np][oq][pp][ce]
[nj]TR[ce]LB[ni:A][cc:B][cq:C]SZ[19])

Here is another example by Fujisawa. To my amateur eye a pincer such as the Magic Sword seems obvious as it helps in the running battle in the centre. But neither player mentioned pincers. According to Go, on his previous move White rejected A instead of the stone just below (he has to do something here to avoid a cap) because it was not sente (enough) and Black would get the big point at B. So he forced Black M7 and then "took territory" with the triangled move. So the need to take territory (cf. Black's lower right corner) apparently took precedence over a pincer.

In the same vein, just a couple of moves later, Go invaded at the lower left 3-3 point (C). AG-like, but for the record note that Go did play the hanetsugi.

(;AB[ee][pd][pp][ep][fp][or][mc][qj][ce][de][dd][bd][ec][fc]AW[cp][eq][dq][nq][di]
[df][hd][gb][eb][dc][cb][bc][cd][cc]TR[or]LB[pn:A][jp:B][dn:C]SZ[19])

In this case Go famously played the triangled mole move (very rare, he said - another AG-lik move?). It was not instead of an immediate pincer but rather Black A, White does something on the left side such as C and then Black plays a "bolstered" pincer at B. Go said this would be the usual idea, but White then makes a Go Seigen group on the lower side and so Black doesn't get much out of his pincer. Incidentally, Fujisawa did play an early unbolstered pincer on the upper side.

(;AB[pe][pc][do][cp][fp][er][op][nq][np]AW[dc][cf][qp][dq][bo][cl][oq][pq][qn]TR[oq]
MA[qn]LB[po:A]SZ[19])

In this case, Go chose the triangled move over a pincer, even though you might argue that it would be bolstered to some degree by aji in the lower left. But I chose this example mainly to stress that Go finished the joseki with the X stone. It wasn't joseki then - that was A. This is just a reminder of Go's many innovations we now take for granted. That in turn has two messages: (1) Go had rather more innovations than AG; (2) Pros soon learned to copy Go, so we can assume they will soon learn from AG.

I could give more examples. Suffice it to say that Bill's observation about a bolstered pincer being much preferred over an unbolstered one has seemingly applied in the case of at least one human.

[Bill Spight]

Wonderful post, John!
Many thanks!

Just a couple of quick comments now.

The question now is in what kind of positions do humans play the unbolstered pincer but AlphaGo does not? That's not an easy question to answer, and there is not much evidence to go on.

A fascinating insight, Bill. I have not seen the instructive bolstered/unbolstered paradigm in this form before, but a relative reluctance to play pincers was a feature of Shin Fuseki. There, however, I think the usual explanation is that there were more high positions (and so maybe more emphasis on large moyos) which offered fewer opportunities for pincering.

But the later Go Seigen offers a closer parallel, and maybe also some strong evidence for your hypothesis. You see, for example, a marked reluctance to pincer in his games with Fujisawa Kuranosuke.

I had not noticed that. Verrrry interesting. And great examples!

This is just a reminder of Go's many innovations we now take for granted. That in turn has two messages: (1) Go had rather more innovations than AG; (2) Pros soon learned to copy Go, so we can assume they will soon learn from AG.

Yes, no one in our time, perhaps in the history of go, understood go as well as Go Seigen. He was creative till the end. And so much of modern go bears his stamp.

[jeromie]

I love how an exploration of the moves played by the newest technological innovation in go is leading to a deeper appreciation of Go Seigen's play. Many thanks for the insights!