Let's study AlphaGo's opening book

Uberdude · Post by **Uberdude** » Tue Feb 06, 2018 1:56 pm

Is anyone reading this? Anyway, even if not I'll keep doing it as it's also for my own enjoyment and documenting interesting things.

A shape I've noticed AlphaGo likes to play a lot is the 5th line "peep" (I don't know what to call it) against a large knight move of the opponent from 3rd to 4th line. It's not a new move, humans play it too, but AG does seem to like it a lot and plays it where I think human pros wouldn't (either because they don't consider it or do but dismiss it as aji keshi). Here's an example from AG ancient history, game 2 vs Lee Sedol; this one is a reduction in middle-game position so a fairly typical human usage, in the AG Master teaching tool it's played in looser early opening positions.

Click Here To Show Diagram Code: [go]$$B $$ +---------------------------------------+ $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . X . . . . . . . . . . | $$ | . . X , X . . . . , . . . X . X . . . | $$ | . . . . . . . . . . . . . . . . X . . | $$ | . . . . . . . . . . . . . . . O O . . | $$ | . . W . . . . . . . . . . . . . . . . | $$ | . . . . 1 . . . . . . . O . . . . . . | $$ | . . . 2 . . . . . . . . . . O O . . . | $$ | . . . W . . . . . , . . . X X , . . . | $$ | . . . O X . . . . . . . . . . . . . . | $$ | . . O X . X . . . . . . . . . . . . . | $$ | . . O O X X . . . . . . . . . . . . . | $$ | . O X X X O O . . . . . . . . . O . . | $$ | . O O X O X O X . . . . . . . X O . . | $$ | . X X O O . X O . X . . X . X , O . . | $$ | . X O X . O O . . . . . . X O O . . . | $$ | . . . X . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ +---------------------------------------+[/go]

Here's the same shape with 13 in a micro-Chinese variation. Some brief comments on preceding moves:
- approach of 5 is 45.3%, all 4 shimaris at top left are better with an amusing symmetry: high is 1% better than low, big is a half % better than small.
- answer at 6 is best local move, all pincers worse, but best (by >1%) is to approach top left high or low.
- 7: AG approves of micro-Chinese, best move, shimaris are close behind, mini-Chinese one space lower is -1.5%.
- 8: as always, AG not a fan of wedge (-2.3%), prefers to approach top right from inside or best is outside and go for a mutual moyo type game.
- 9: AG's best, and all 3 normal checking moves on this side (m/n/o17) are better than ones on the left of the wedge.
- 10: AG not impressed by this cool-looking 2nd-line that was fashionable for a while, -4% on normal 2-space extension which is best.
- 11: AG agrees with the humans who play this kosumi in preference to the high shimari answer (and it is human 1st choice 16 to 9 and bigger win %), by 2%.
- 12: normal
- 13: The topic of this post as the move AG likes, but checking human games with this position it is also pros favourite move, 5 hits in waltheri (all in 2012-13)! This obviously aims at splitting white at j17, and then also covering at g15 if white defends the top. The most common human response is a, which defends j17 and also makes the g15 attachment ineffective.

Click Here To Show Diagram Code: [go]$$Bcm5 $$ +---------------------------------------+ $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . 6 . . . . . . . . . . . . . | $$ | . . . X . . . . . 4 . . . 5 . . . . . | $$ | . . . , 7 . 8 a . , . . . . . X . . . | $$ | . . . . . . . . 9 . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . 3 . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . , . . . . . , . . . . . , . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . 1 . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . O . . . . . , . . . . . O . . . | $$ | . . . . . 2 . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ +---------------------------------------+[/go]

AlphaGo tool gives 2 responses for white, the obedient one at j16 (1 human game), and resisting with d15 (no humans). j16 has the advantage of taking a liberty from the black stone and better for coming out to right centre (e.g. k15), downside is g15 is still a decent black move (the human did it immediately). AG 3-3 invades the lower right first:

Click Here To Show Diagram Code: [go]$$Wcm14 AG continuation if defend: 3-3... $$ +---------------------------------------+ $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . O . . . . . . . . . . . . . | $$ | . . . X . . . . . O . . . X . . . . . | $$ | . . . , X . O . 1 , . . . . . X . . . | $$ | . . . . . . . . X . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . X . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . , . . . . . , . . . . . , . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . 0 . | $$ | . . X . . . . . . . . . . . . . 8 7 . | $$ | . . . . . . . . . . . . . . . 9 5 6 . | $$ | . . . O . . . . . , . . . . . O 4 . . | $$ | . . . . . O . . . . . . . . . 3 2 . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ +---------------------------------------+[/go]

Click Here To Show Diagram Code: [go]$$Wcm24 ... then block at 27 $$ +---------------------------------------+ $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . O . . . . . . . . . . . . . | $$ | . . . X . . . . . O . . . X . . . . . | $$ | . . . , X 9 O . O , . . . . . X . . . | $$ | . . . . . . 4 8 X . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . X . . . . . . . . . . . . . . . . | $$ | . . 6 5 . . . . . . . . . . . . . . . | $$ | . . . , . . . . . , . . . . . , . . . | $$ | . . . 7 . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . X . | $$ | . . X . . . . . . . . . . . . . X . 2 | $$ | . . . . . . . . . . . . . . . O O X . | $$ | . . . O . . . . . , . . . . . O X 1 . | $$ | . . . . . O . . . . . . . . . O X 3 . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ +---------------------------------------+[/go]

Something I noticed is white plays the double hane joseki here, which is not rare for AG but jump is more common. I think this could be because j15 broke the ladder: we don't get a win% for jump but my suspicion is AG thinks that is better for white than the double hane if white has the ladder. So the 3-3 (and j15 to set it up) could be seen as urgent and wanting to get the good outside ponnuki result whilst the ladder works for black, but tbh I don't really see why getting that outside ponnuki in sente is a good exchange: AG likes corners and W got the corner.

Click Here To Show Diagram Code: [go]$$Wcm18 The joseki that needs ladder $$ +---------------------------------------+ $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . O . . . . . . . . . . . . . | $$ | . . . X . . . . . O . . . X . . . . . | $$ | . . . , X . O . O , . . . . . X . . . | $$ | . . . . . . . . X . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . X . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . , . . . . . , . . . . . , . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . a 7 . | $$ | . . X . . . . . . . . . . . c 0 1 4 . | $$ | . . . . . . . . . . . . . . . 3 2 . . | $$ | . . . O . . . . . , . . . . . O X . . | $$ | . . . . . O . . . . . . . . . O X . . | $$ | . . . . . . . . . . . . . . 9 8 5 6 . | $$ | . . . . . . . . . . . . . . . . b . . | $$ +---------------------------------------+[/go]

Instead of obediantely answering j15, AG suggests resisting and mutual destruction is a little (0.6%) better. Is there any meaning to interposing 19-20 during the top side sequence, or just random bot flitting?

Click Here To Show Diagram Code: [go]$$Wcm14 AG continuation if resist... $$ +---------------------------------------+ $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . O . . . . . . . . . . . . . | $$ | . . . X . . . . 4 O . . . X . . . . . | $$ | . . . , X . O 8 5 9 . . . . . X . . . | $$ | . . . 1 2 . . 0 X . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . 3 . . . . . . . . . . . . . . . | $$ | . . X 6 7 . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . , . . . . . , . . . . . , . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . X . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . O . . . . . , . . . . . O . . . | $$ | . . . . . O . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ +---------------------------------------+[/go]

Here I can see the benefit of making the 27-28 exchange before taking gote at 29, black probably doesn't want white to extend at 27 if at 29 immediately.

Click Here To Show Diagram Code: [go]$$Wcm24 ... cont $$ +---------------------------------------+ $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . O 6 . 3 . . . . . . . . . . | $$ | . . . X . . 2 1 . O . . . X . . . . . | $$ | . . . , X . O X O O . . . . . X . . . | $$ | . . . O X . . X X . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . O . 5 . . . . . . . . . . . . . | $$ | . . X X O . . . . . . . . . . . . . . | $$ | . . . . 4 7 . . . . . . . . . . . . . | $$ | . . . , 8 . . . . , . . . . . , . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . X . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . O . . . . . , . . . . . O . . . | $$ | . . . . . O . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ +---------------------------------------+[/go]

lightvector · Post by **lightvector** » Tue Feb 06, 2018 9:01 pm

Uberdude wrote:Is anyone reading this? Anyway, even if not I'll keep doing it as it's also for my own enjoyment and documenting interesting things.

I'm reading this! Please keep it up, this thread is awesome.

Tryss · Post by **Tryss** » Tue Feb 06, 2018 9:04 pm

Uberdude wrote:Is anyone reading this?

I am

Mikebass14 · Post by **Mikebass14** » Tue Feb 06, 2018 10:32 pm

Me too! Maybe too fast to really absorb, but enjoying it all the same. Thanks!

Uberdude · Post by **Uberdude** » Wed Feb 07, 2018 5:00 am

Ok, thanks for encouragement!

I'll try to find an example of this shape that humans didn't do for the next post. Btw, does anyone know if it has a name, either English or C/J/K?

John Fairbairn · Post by **John Fairbairn** » Wed Feb 07, 2018 5:58 am

I'll try to find an example of this shape that humans didn't do for the next post. Btw, does anyone know if it has a name, either English or C/J/K?

It's called nozomi (gazing from a distance) in Japanese.

Uberdude · Post by **Uberdude** » Wed Feb 07, 2018 6:43 am

John Fairbairn wrote:It's called nozomi (gazing from a distance) in Japanese.

Thanks: that's nice, fits my feeling of wanting to call it a peep but a bit further away.

Uberdude · Post by **Uberdude** » Wed Feb 07, 2018 3:06 pm

Here's an example of AG wanting to play this nozomi from one of the master games from 2017 new year. The human pro played a instead for 14 which is a classic large extension eyeing the attachment at b in the corner next. AG's move destroys this possibility, but it thinks it's 2.6% better (black is already at 54%, mostly because AG didn't like the c11 tenuki). What does it gain? Importantly it keeps sente which AG likes (and then uses to enclose lower left), but being sente is nothing good in itself, why not just enclose directly? I thought it might make the ladder good for the 3-3 invasion joseki from before, but it doesn't, plus that joseki probably wouldn't happen with r10 in place; maybe it changes another ladder. It helps c11 and develops the centre a little bit, plus I get the feeling it makes black c13 smaller, and also has a potential followup at g16 to reduce the top and develop the centre, but those all seem quite vague to me. I wonder what the win% would be for f3 directly, I suspect much the same: it's not an essential exchange to play now, but who knows...

Click Here To Show Diagram Code: [go]$$Wcm10 AlphaGo (black) vs Yang Dingxin 5p $$ +---------------------------------------+ $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . b . . X . . . . . . . O X X . . . | $$ | . . X 6 . . . . . , . . 4 2 O , X . . | $$ | . . . . 5 . . . . . . . . . . . . . . | $$ | . . a . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . 1 . . . . . . . . . . . . . . . . | $$ | . . . , . . . . . , . . . . . , 3 . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . O . . . . . , . . . . . O . . . | $$ | . . . . . 7 . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ +---------------------------------------+[/go]

johnsmith · Post by **johnsmith** » Wed Feb 07, 2018 3:18 pm

I'm reading too. From time to time

it's very tiring to make these ASCI diagrams (or whatever the name is) or I don't know the easy way. So I can't exchange my opinions easily and end up not writing anything... Are screenshots instead of diagrams desirable on this forum? Something like this:

By the way: Zen 7 is proposing only this "bad" move for white, and it's the only move it considers

. While the most recent LZ network d6f3a68b plays the correct move. I noticed many good moves like this by LZ that AG taught us.

Edit: diagram

Click Here To Show Diagram Code: [go]$$Wc $$ +---------------------------------------+ $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . X . . O . . | $$ | . . . O . . . . . , . . . . . X . O . | $$ | . . . . . . . . . . . . . . 5 6 X O . | $$ | . . . . . . . . . . . . . . . X O . . | $$ | . . . . . . . . . . . . . . . 2 1 . . | $$ | . . . . . . . . . . . . . . . . X 3 . | $$ | . . . . . . . . . . . . . . . . . 4 . | $$ | . . . , . . . . . , . . . . . , . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . O . . . . . , . . . . . , X . . | $$ | . . . . . 7 . . . . . . . . X . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ +---------------------------------------+[/go]

Uberdude · Post by **Uberdude** » Wed Feb 07, 2018 3:39 pm

johnsmith wrote: it's very tiring to make these ASCI diagrams (or whatever the name is) or I don't know the easy way.

Thanks to Herman: http://hiddema.nl/diagrammer/

Uberdude · Post by **Uberdude** » Wed Feb 07, 2018 4:27 pm

And another from the Master series. In the real game Master played j3 for 28 (best, Park Junghwan as black was already down at 40%), but the teaching tool version also likes (-0.2%) the nozomi at o15 on top, expecting black to answer at p17 and then come back to j3. With j3 directly it then approves of Park's c5 attachment etc (miai with the extension on lower side I think). In the real game Master played 34 at f8, an elegant shoulder hit that Inseong praised in one of his videos. AG teaching tool version suggests f7 or the o15 nozomi again. So it doesn't really matter if it was before or after j3, but it does seem to think it's a key point. I think many humans (myself included) would be somewhat reluctant to exchange it for black's defence as there was previously some chance to live or ko at 3-3 (and indeed in the real game Master did live at 3-3 later).

Click Here To Show Diagram Code: [go]$$Wcm28 AG Master (white) vs Park Junghwan 9p $$ +---------------------------------------+ $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . O . . . . . . . . . . . . . . | $$ | . . . X O . . O . X . . X . 8 . . . . | $$ | . . . X . . . . . , . . . . . X . . . | $$ | . . X . . O . . . . . . . 7 . . . . . | $$ | . . X O . . . . . . . . . . . . X . . | $$ | . . X X O O . . . . . . . . . . . . . | $$ | . . . O X . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . , . . . . . , . . . . . , . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . 6 . . . . . . . . . . . . . . | $$ | . . 4 . . . . . . . . . . . . . O . . | $$ | . . 2 3 . . . . . . . . . . . . . . . | $$ | . 5 O , . . . . . , X . . X . O . . . | $$ | . . . . O . . . 1 . . . . X O . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ +---------------------------------------+[/go]

But I think why AG likes this exchange become clear in the followup at m16, it wants to press black low, if block at m17 then k16 cover is nice, so black resists. In fact many moves earlier when Park defended at n17 AG preferred (by <1%) him to jump at k15 instead, maybe this future nozomi-press overconcentration combination is one reason why.

Click Here To Show Diagram Code: [go]$$Wcm36 nozomi continuation $$ +---------------------------------------+ $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . O . . . . . . . . . . . . . . | $$ | . . . X O . 5 O . X . 3 X . X . . . . | $$ | . . . X . . . 4 2 , . 1 . . . X . . . | $$ | . . X . . O . . . . . . . O . . . . . | $$ | . . X O . . . . . . . . . . . . X . . | $$ | . . X X O O . . 6 . . . . . . . . . . | $$ | . . . O X . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . , . . . . . , . . . . . , . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . X . . . . . . . . . . . . . . | $$ | . . X . . . . . . . . . . . . . O . . | $$ | . . X O . . . . . . . . . . . . . . . | $$ | . O O , . . . . . , X . . X . O . . . | $$ | . . . . O . . . O . . . . X O . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ +---------------------------------------+[/go]

johnsmith · Post by **johnsmith** » Wed Feb 07, 2018 4:44 pm

Park also quickly adopted AG's joseki in today's game against Ke Jie 9p. Instead of 'a', he continued with 1 (modified AG joseki).

Click Here To Show Diagram Code: [go]$$Wc Ke(black) vs Park(white) $$ --------------------+ $$ . . . . . . . . . . | $$ . . . . . . . . . . | $$ . . 6 4 3 1 O O . . | $$ , . . 5 2 X X X a . | $$ . . . . . . . . . . | $$ . . . . . . . O . . | $$ . . . . . . . . . . | $$ . . . . . . . X . . | $$ . . . . . . . . . . | $$ , . . . . . , . . . |[/go]

John Fairbairn · Post by **John Fairbairn** » Thu Feb 08, 2018 3:16 am

But I think why AG likes this exchange.... this future nozomi-press overconcentration combination is one reason why.

While not in any way demurring from your conclusion, I again raise the likelihood that this has all been considered before by pros, especially in the New Fuseki theorising. 5th line plays attracted them - recall Kitani's famous game where he started with three of them, like a high sanrensei. Among the main reasons were adaptability and potentiality for territory.

For human pros, adaptability was perhaps the bugbear. They soon found themselves incapable of controlling the complications in the centre. But that did not mean they gave up their views on the ideal theory. I think what we are seeing with AG is proof of that concept because AG can control the complications. Under that view, should humans try harder to cope with centre complications, or just give up, the way New Fuseki-ites did?

The answer to that may lie in the second point: potentiality for territory.

One of the main but counter-intuitive strands in New Fuseki thinking was that 5th line plays were good for making territory. You need to refer to the diagrams in Shin Fuseki-ho to get a firm grip on that, but, to boil it down, the main conclusion was that a box is geometrically much more efficient than a tray for garnering territory. This was manifested in two ways.

One was that 5th line plays can tend to end up in box shapes for the 5th-line player. It's not New Fuseki, but there's an interesting example of such innovative thinking by Dosaku in his earliest datable game (1665). Here he played a long series of presses (perhaps AG copied this

) to get a long wall and then sealed off a 5th line territory around it - not using his thickness to attack, but to make territory. In fact there were several other early presses in this game by both sides, so what we may be seeing is the emergence of a strand of theory that was new at the time. It may even be considered pre-thickness and that it led to the concept of centre thickness - another feather in Dosaku's cap?

But the other way the box-tray dichotomy came up was the realisation that pressing your opponent down into a tray shape (using presses and shoulder hits mainly) was, in theory, a good thing for you (and bonus points if your pressing moves got a box side for yourself, of course). This didn't quite get off the ground. One reason must have been the ensuing difficulties, already mentioned, in dealing with nebulous centre positions, but I suspect lack of komi also played a big part. White would surely have been reluctant to give Black solid territory, even in a tray shape, when Black had the cushion of no komi, and at the same time White, having to rely on seeking complications to overcome Black's first-move advantage, would have been reluctant to settle positions and so remove aji.

The introduction of komi did not solve White's problems at once, because first it was only 4.5 points and then only 5.5. points. The big komi is a relatively recent development.

On that reading, modern pros have made quite the same advances in strategy/theory that they did in tactics/fighting, and AG is reminding them to go back and think more about what previous theoreticians, from Dosaku to Kitani and Go Seigen, thought about.

That and taking more of an interest in how AG controls the later centre game (box shape potentiality?) seems more likely to me to help humans improve, rather than quibbling over joseki minutiae. Uberdude's nozomi observation seems like a very good start.

Uberdude · Post by **Uberdude** » Mon Feb 12, 2018 7:49 am

A brief interlude in the nozomi theme with something I found remarkable in the AG vs Lee Sedol game 2 opening.

Click Here To Show Diagram Code: [go]$$Bcm11 Ok for B, 46.8% after 13 $$ +---------------------------------------+ $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . 3 . . . . . . . . . . | $$ | . . X , . . . . . , . . . . . X . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . , . . . . . , . . . . . , . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . X . . . . . . . . . . . . . 2 . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . O . . . . . , . . 1 . X , O . . | $$ | . . . . . O . . . . . . . X O O . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ +---------------------------------------+[/go]

AG made the hanging connetion of 11, Lee played the usual joseki one-space extension to 12 and then AG tenukid to make a Chinese opening rather than extend on the lower side. The AG Master version which made this teaching tool has some different evaluations to the weaker AG Lee version, but it gives black win% in this position as 46.8%. Something I remember being taught (though how accurately does this reflect the current thinking of top pros?) is that making the connection makes the 2 black stones turn into 3 stones and become heavier: if just 2 you can tenuki and treat them lightly if white cuts, but by connecting you are commiting more to making a group out of them so extendind on the lower side would be normal (and white's extenion helped white on the right side and made it hard to develop there). However, AG strongly disagrees with this, saying the immediate tenuki to make a Chinese is a whopping 9% worse, and white punishes by cutting.

Click Here To Show Diagram Code: [go]$$Bcm11 Bad for B, 37.6% after 11 $$ +---------------------------------------+ $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . 1 . . . . . . . . . . | $$ | . . X , . . . . . , . . . . . X . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . , . . . . . , . . . . . , . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . X . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . O . . . . . , . . . . X , O . . | $$ | . . . . . O . . . . . . . X O O . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ +---------------------------------------+[/go]

So why the huge difference? To start with AG teaching tool actually thinks the hanging connection was bad (-1% on solid connection) and black is already down at 42%: high approach was bad (better low), and approach on left bad (better 3-3 or connect). But then 12 joseki extension is a big mistake, -5.5%, better to approach the top left 3-4. If black made the solid connection then AG thinks extend is a good move; this is something that has changed as AG evolved, it now generally considers the hanging connection soft as it's gote whereas the solid connection has a more severe follow up of the attachment and then hane (r5 and s6) that Go Seigen liked. So I think we can understand this as AG views the hanging connection for extend as a good exchange for black, making the 2 stones stronger in sente as white made a soft answer, rather than a bad exchange making them heavier. Also AG Master is not impressed by the famous q5 peep: it thinks it is a mistake (45.5%, c4 attach best at 48%) because white should resist with the o5 counter peep but if white meekly connects at r5 (as Lee Sedol did) then black goes up to 49%. I.e. peep was an overplay that Lee didn't punish.

Bill Spight · Post by **Bill Spight** » Mon Feb 12, 2018 11:43 am

Click Here To Show Diagram Code: [go]$$Bcm11 Bad for B, 37.6% after 11 $$ +---------------------------------------+ $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . 1 . . . . . . . . . . | $$ | . . X , . . . . . , . . . . . X . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . , . . . . . , . . . . . , . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . X . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . W . . . . . , . . . 2 X , O . . | $$ | . . . . . W . . . . . . . X O O . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ +---------------------------------------+[/go]

I wonder if one reason for the bad marks for

has to do with the presence of the

stones, in that they make the cut,

, more potent than if the bottom left corner were empty.

Life In 19x19

Let's study AlphaGo's opening book

Re: Let's study AlphaGo's opening book

Re: Let's study AlphaGo's opening book

Re: Let's study AlphaGo's opening book

Re: Let's study AlphaGo's opening book

Re: Let's study AlphaGo's opening book

Re: Let's study AlphaGo's opening book

Re: Let's study AlphaGo's opening book

Re: Let's study AlphaGo's opening book

Re: Let's study AlphaGo's opening book

Re: Let's study AlphaGo's opening book

Re: Let's study AlphaGo's opening book

Re: Let's study AlphaGo's opening book

Re: Let's study AlphaGo's opening book

Re: Let's study AlphaGo's opening book

Re: Let's study AlphaGo's opening book