OK, lightvector got to it first :-) I too don't believe there's a developer's Conspiracy to Hide the Truth from Bill.

On the one hand, I could write a little essay about the spectrum from classical statistical models to purely empirical machine learning, and Hastie and Tibshirani's attempt to define a reasonable middle ground under the name "statistical learning". And I could remind you of the difference between frequentist and Bayesian statistics, and the difficulty of defining what it is we're trying to measure when we say "winrate". But you already know all that. (We've had this conversation before: the margin of error is already there! If LZ says 93%, then the margin of error is surely 7%. Or maybe 93% on a bad day.)

On the other hand, if what you're asking for is "how confident is the machine in this prediction", I think we already have nearly as much information as we could wish for. Fundamentally, it's trying to predict whether black or white will win. If it says 93%, it's saying this is a very confident prediction. If it says 55%, it's saying maybe one side has a slight edge, but with low confidence. When you ask Lizzie to show you the best move, you quickly see whether the machine can identify a clear-cut "correct move" or whether it's struggling to decide between alternatives. With Lizzie+KataGo, the KataEstimate button will colour in points black or white for who is likely to control which areas, and shades of grey for where it's not sure.

And if that's not enough, we can inspect the search tree in considerable detail. (I haven't forgotten that I intend to post some ladder and ko examples there. Just need to find a free evening or two to write them up. Darn real life, intruding on go again...)

So much amazing progress these last five years! Bill, what more does it take to satisfy you? :-)

PS thanks for the link to Yarin Gal's blog. I've heard of dropout in neural networks before, but not looked closely at it. In image recognition, if you mask random parts of an image and then still try and guess whether it's a cat or dog, that's a pretty reasonable question. In, go if you mask random stones on a go board and then try to guess who's winning or what the best move is... Well, sometimes you're wrapped up in a big local fight and it really doesn't make much difference what the rest of the board looks like. Or sometimes you're making a joseki choice based on the adjacent corners, and the diagonally opposite corner wouldn't influence the choice so much. So masking a few random stones wouldn't change your assessment. Certainly humans don't consciously consider the position of literally every stone on the board when thinking about every move. But other times, taking even one key stone off the board will make a radical difference. Perhaps averaged over a million training examples, the noise cancels out and we're left with good predictions plus a better appreciation of uncertainty? Or maybe this approach is just too chaotic for go?

Well, there is a post that I have had in the back of my head for some time, about just noticeable differences, chaos on the go board, and training. I have actually addressed the question here same years ago in regard to human training, without using the jargon. I didn't want to say anything about training bots, because it could be I would be talking through my hat. But it's an idea I have wanted to play around with and get some data on, with my new axe. I had not thought of masking an intersection as a kind of just noticeable difference, but it is.

BTW, the original dropout method dropped 50% ( ) of intermediate layers and only 20% of the input layer. That seems extreme for go, And the original method did not work for recurrent networks. Now Gal makes it work. Interesting stuff.

_________________
The Adkins Principle:
At some point, doesn't thinking have to go on?
— Winona Adkins

Visualize whirled peas.

Everything with love. Stay safe.

A passing thought: is one colour go a form of drop-out training for humans?

Well, switching the color of a point could be considered a just noticeable difference.

_________________
The Adkins Principle:
At some point, doesn't thinking have to go on?
— Winona Adkins

Visualize whirled peas.

Everything with love. Stay safe.

Unplanned obsolescence

In the AI era a number of joseki are gone or on the way out. That makes sense, as the bots have advanced the top level of go by decades if not centuries. Uberdude recently started a topic ( https://lifein19x19.com/viewtopic.php?t=17352 ) about what he appropriately dubbed the 3-3 double hane switcheroo ponnuki joseki. An example, from Kim Mili, 3 dan, (White) vs. Cho Hyeyeon, 9 dan, on May 16, 2018, is below.

Click Here To Show Diagram Code

[go]$$Wcm50 Switcheroo shocker
$$ ---------------------------------------
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . X O . . . . |
$$ | . . O . X O . . . . . . X O O O O . . |
$$ | . . O X . X . . X , . . X X O X X . . |
$$ | . . . . . . . . . . . . . O X . . . . |
$$ | . . . O . . . . . . . . . O . X . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . X . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . , . . . . . , . . . . . , . . . |
$$ | . . . . . . . . . . . . . . . O . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . 6 . . . . . . . . . . . . . O X . . |
$$ | 8 3 4 . . . . . . . . . . O . O . . . |
$$ | . 2 O O 5 . . . . , . . X O X O O . . |
$$ | . 7 X X O . . . . . . . . X X X O X . |
$$ | . . 9 . X 1 . . . . . . . . . . X O . |
$$ | . . . . . . . . . . . . . . . . . X . |
$$ ---------------------------------------[/go]

Instead of capturing in the usual joseki, Cho opted to hane on the left side and capture . According to the Elf commentary, by comparison this decision cost Cho a whopping 37% in winrate! Surprisingly, it seems that the switcheroo is typically a mistake, if not a blunder.

Still, Uberdude found an example where the switcheroo was correct ( ), according to KataGo, from Pak Yeonghun, 9 dan, (White) vs. Paek Hongseok, 7 dan, on June 27,2009. Elf agrees, judging that the switcheroo gains 4½% in winrate by comparison.

Pros may not have completely abandoned the switcheroo, as it seems to be appropriate in some positions. However, it apparently can be a game losing blunder, one which even 9 dans have misjudged.

_________________
The Adkins Principle:
At some point, doesn't thinking have to go on?
— Winona Adkins

Visualize whirled peas.

Everything with love. Stay safe.

Unplanned obsolescence, II

Mistakes

Can a mistake be a joseki? Obviously, it can. A joseki is simply a standard sequence of play, and over time the community of go players learns better plays in many instances, and joseki become obsolete. OC, sometimes an obsolete move or joseki makes a comeback. For instance, the mini-Chinese made a comeback after 200 years, and the initial 4-4 move made a comeback in Japan after a much longer period. Now it is usually the preferred first move in the corner.

It was known in the mid 20th century that there was something wrong with the sequence for White in the example below, but it was still considered to be joseki.

Click Here To Show Diagram Code

[go]$$Wc
$$ ---------------------------------------
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . , . . . . . , . . . . . , . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . , . . . . . , . . . . . , 7 . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . 5 3 . . |
$$ | . . . . . . . . . . . . . . . 1 2 . . |
$$ | . . . , . . . . . , . . . . . , 4 . . |
$$ | . . . . . . . . . . . . . 6 . X . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ ---------------------------------------[/go]

One idea was not to connect at 5, but to occupy the top right corner instead. It took AlphaGo to teach us that the solid connection is fine, but White can tenuki instead of playing the extension. While not exactly heresy, this was a surprise, because it had been believed that because , , and lacked eye potential, they needed an extension to make a base.

Click Here To Show Diagram Code

[go]$$Wcm6 Tang Yi, 3 dan (W) - Wang Yubo, 2 dan, 2018-07-13
$$ ---------------------------------------
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . O . . . . . . . . . . . . . . . |
$$ | . . . , . . . . . , . . . X . , X . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . a . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . , . . . . . , . . . . . c 7 . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . b . . . . . . . . . . . . 5 3 . . |
$$ | . . . . . . . . . . . . . . . 1 2 . . |
$$ | . . . , . . . . . , . . . . . , 4 . . |
$$ | . . . O . . . . . . . . . 6 . X . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ ---------------------------------------[/go]

So is a mistake? Maybe White should make an enclosure, for instance at a or b. Actually, Elf, in its commentary, prefers the high extension at c. But only by 1%. Surely a preference that slight does not indicate that the low extension is a mistake.

Actually, the date is a big clue that is OK. By 2018 pros were checking their opening plays with AI. It is rare to find an opening error by them nowadays.

How about the next example?

Click Here To Show Diagram Code

[go]$$Wcm8 Pak Cheongsang, 9 dan (W) - Yun Chunsang, 7 dan, 2008-07-13
$$ -------------------------------------
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . X . . . . . . . . . . . . . . . |
$$ | . . . . . X . . . . . . . . a . . . . |
$$ | . . . O . . . . . , . . . . b , X . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . O . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . , . . . . . , . . . . . , 7 . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . c . . . . . . . . . . . . 5 3 . . |
$$ | . . . . . . . . . . . . . . . 1 2 . . |
$$ | . . . , . . . . . , . . . . . , 4 . . |
$$ | . . . O . . . . . . . . . 6 . X . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ ---------------------------------------[/go]

Is a mistake? Should White approach the top right corner at a or b, or enclose the bottom left corner at c? Elf prefers all three to the extension, and prefers the high approach at b by 5%. This game was played before the AI era, OC.

So is a mistake? Well, maybe. IMHO, an educated guess, is that it is, according to Elf, but just barely. I have enough experience with the Elf commentaries that I was pretty sure that Elf would prefer an approach the the top right corner by enough to say that the extension was a mistake. Now, Elf is only one bot, and the commentary is a year and a half old. Bots are getting better all the time. Maybe another bot would prefer the extension.

Still, as a player I could afford to avoid the extension, even if it is not a mistake. How bad is it to emulate a superhuman player? But as an analyst I worry about whether the extension is a mistake or not. Pak, a 9 dan pro, preferred the extension. Was he wrong?

While I'm at it, what about the idea of leaving the connection unplayed? Since AlphaGo played it, maybe not playing it is a mistake.

Click Here To Show Diagram Code

[go]$$Wcm10 Ch'oi Ch'eolhan, 9 dan (W) - Kang Tongyun, 9 dan, 2018-02-13
$$ ---------------------------------------
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . 7 . . . . . |
$$ | . . . . . . . . . . . . . 4 5 3 1 . . |
$$ | . . . O . . . . . , . . . . 6 X 2 . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . , . . . . . , . . . . . , a . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . 9 . . |
$$ | . . . . . . . . . . . . . . 0 8 O . . |
$$ | . . X . . . . . . . . . . . . O X . . |
$$ | . . . , . . . . . , . . . . . , X . . |
$$ | . . . O . . . . . . . . . . . X . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ ---------------------------------------[/go]

at a

Instead of making the solid connection White jumped into the top right corner. Was that a mistake?

Elf thinks so, to the tune of 9½%. That winrate difference is more substantial than 5%, enough for me to guess that it is a mistake, and that other top bots will agree that it is, if not with the exact estimate of the winrate difference. Besides, it wasn't just the fact that AlphaGo played the connection, it is that I have seen Elf's opinion of other omissions of the connection. In fact, a winrate difference of 9½% is on the low side. Did a pro 9 dan make a mistake here in 2018? My educated guess is yes. But nobody really knows.

_________________
The Adkins Principle:
At some point, doesn't thinking have to go on?
— Winona Adkins

Visualize whirled peas.

Everything with love. Stay safe.

A recent KataGo 40 block network (b40c256x2-s2619890176-d761667663, so slightly newer than the ones released, but again probably similar) clearly dis-prefers white's play, enough to probably never choose to play this way itself. But taking the evaluation at face value for now, calling it a mistake might be a stretch, it thinks the difference is pretty slight. See followups and evaluations below.

Click Here To Show Diagram Code

[go]$$Wc Not Kata's preferred way for white
$$ ---------------------------------------
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . O . . . . . |
$$ | . . . . . . . . . . . . . X O O O . . |
$$ | . . . O . . . . . , . . . . X X X . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . , . . . . . , . . . . . , 1 . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . 2 3 . . |
$$ | . . . . . . . . . . . . . . . . O . . |
$$ | . . . . . . . . . . . . . . X X O . . |
$$ | . . X . . . . . . . . . . . . O X . . |
$$ | . . . , . . . . . , . . . . . , X . . |
$$ | . . . O . . 4 . . . . . . . . X . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ ---------------------------------------[/go]

If white plays the two point extension, Kata expects black to force and then build the bottom with a pincer. Seems pretty straightforward. (Black ~54.5%, +0.5 points)

Click Here To Show Diagram Code

[go]$$Wc Kata's different idea for white
$$ ---------------------------------------
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . O . . . . . |
$$ | . . . . . . . . . . . . . X O O O a . |
$$ | . . . O . . . . . , . . . . X X X . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . c b . . |
$$ | . . . , . . . . . , . . . . . , . . . |
$$ | . . . . . . . . . . . . . . . 1 . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . d . . O . . |
$$ | . . . . . . . . . . . . . e X X O . . |
$$ | . . X . . . . . . . . . . f . O X . . |
$$ | . . . , . . . . . , . . . . . , X . . |
$$ | . . . O . . . . . . . . . . . X . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ ---------------------------------------[/go]

Kata actually mildly prefers this odd-looking knight's move, which at first sight feels cramped. My amateur dan understanding is Kata wants to avoid black forcing from above as in the above diagram, and the higher knight move activates some aji in Q5 better. Kata expects black to perhaps play "a" next. If/when black plays "b", white plans to answer with "c", and depending on what the white group on the right needs or what happens on the bottom in different variations, variously plans to use one of d, e, or f to get value out of Q5 and the higher knight move. (Black ~53.5%, +0.4 points).

Running forward a bit more though, actually it seems like some variations end up with black back at about 54.5%, so maybe this ends up being similar in evaluation to the two-point extension, although with a very different resulting game.

Click Here To Show Diagram Code

[go]$$Wc Earlier for white
$$ ---------------------------------------
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . O . . . . . , . . . . . X . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . d . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . , . . . . . , . . . . . c . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . 1 O . . |
$$ | . . X . . . . . . . . . . . . O X . . |
$$ | . . . , 2 4 . . . , . . . a . , X . . |
$$ | . . . O 3 . 5 . . . . . . b . X . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ ---------------------------------------[/go]

Expected line for the solid connect. Next black plays "a" or "b", and white plays "c" or "d" or maybe other moves. As mentioned, clearly preferred to either of the earlier two results: (Black ~50.5%, +0.0 points). But that's quite small of a difference by human standards.


Edit: All of the above was interactively in Lizzie, waiting for often around 60k-120k visits each move. Since the players seem to be Korean, I took a guess and also went with Japanese/Korean rules, 6.5 komi.

Many thanks.

I see I was not clear. The 9½% winrate difference (as we know, Elf calculates larger differences than other top bots) is between the solid connection for and in the game. To be precise, for the solid connection Elf estimates White's winrate as 48.2% (94,223 rollouts). in the game, at R-17, got only 1 rollout, so Elf inherited its winrate estimate from Elf's top choice for , which was Q-17, not the game play, which was the block at R-16. (It would have been preferable to have Elf actually make the play at R-17 instead, but Elf did not do that. {shrug}). That yields a winrate estimate for White of 38.5% (29,001 rollouts). The winrate difference is 9.7%, which I rounded to 9½% because I don't trust the third digit.

I gave the game continuation to give the reader an picture of what was going on. Through Black has lost a couple of percent by Elf's estimation, while after all of White's plays through have been Elf's top choice. I had intended to give around 10 plays from ELf's main variation for the solid connection to show a comparison, but I forgot to do so. I'll do so below.



Elf agrees that was not optimal, and gives the following in reply.

Click Here To Show Diagram Code

[go]$$Wcm20 Elf also likes Black 21 here
$$ ---------------------------------------
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . O . . . . . |
$$ | . . . . . . . . . . . . . X O O O 4 . |
$$ | . . . O . . . . . , . . . . X X X . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . , . . . . . , . . . . . , 1 . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . 2 3 . . |
$$ | . . . . . . . . . . . . . . . . O . . |
$$ | . . . . . . . . . . . . . . X X O . . |
$$ | . . X . . . . . . . . . . . . O X . . |
$$ | . . . , . . . . . , . . . . . , X . . |
$$ | . . . O . . . . . . . . . . . X . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ ---------------------------------------[/go]

For Elf estimates Black's winrate as 63.6% (40,357 rollouts). (As we know, Elf likes Black's chances. )



Elf agrees, at least with the keima for .

Click Here To Show Diagram Code

[go]$$Wcm20 Elf agrees on White 20
$$ ---------------------------------------
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . O . . . . . |
$$ | . . . . . . . . . . . . . X O O O b . |
$$ | . . . O . . . . . , . . . . X X X . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . a . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . d c . . |
$$ | . . . , . . . . . , . . . . . , . . . |
$$ | . . . . . . . . . . . . . . . 1 . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . O . . |
$$ | . . . . . . . . . . . . . . X X O . . |
$$ | . . X . . . . . . . . . . . . O X . . |
$$ | . . . , . . . . . , . . . . . , X . . |
$$ | . . . O . . . . . . . . . . . X . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ ---------------------------------------[/go]

In reply it expects Black to play at a, b, or c, in that order of preference. If Black replies at c it also likes the jump attachment at d. For the keima it estimates Black's winrate as
58.6% (205,470 rollouts). Based on that, maybe in the game was a minor error, according to Elf. (One reason I still like the Elf commentaries is the humungous number of rollouts. )



Not sure what you mean. Are you referring to an existing variation, or are you making each move yourself?



Yes, it was a Korean league game with 6.5 komi. 1 hr. main time, sudden death. Black won by resignation.

For comparison, here is Elf's mainline for the solid connection, up through .

Click Here To Show Diagram Code

[go]$$Wcm10 Elf's mainline for the solid connection
$$ ---------------------------------------
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . 9 . . . |
$$ | . . . O . . . . . , . . . . . X . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . 8 . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . , . . . . . , . . . . . 7 . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . 1 O . . |
$$ | . . X . . . . . . . . . . . . O X . . |
$$ | . . . , 2 4 . . . , . . . 6 . , X . . |
$$ | . . . O 3 . 5 . . . . . . . . X . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ ---------------------------------------[/go]

Elf and KataGo agree through , maybe through . is a nice touch, preventing Black from playing there if White invaded on R-17 instead.

_________________
The Adkins Principle:
At some point, doesn't thinking have to go on?
— Winona Adkins

Visualize whirled peas.

Everything with love. Stay safe.

I am unsure whether I understand you. Is the diagram above 37% better than Cho's variation? Please show Cho's variation with a diagram! What was the 37% mistake in it?

Robert

Click Here To Show Diagram Code

[go]$$Wcm50 Switcheroo shocker
$$ ---------------------------------------
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . X O . . . . |
$$ | . . O . X O . . . . . . X O O O O . . |
$$ | . . O X . X . . X , . . X X O X X . . |
$$ | . . . . . . . . . . . . . O X . . . . |
$$ | . . . O . . . . . . . . . O . X . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . X . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . , . . . . . , . . . . . , . . . |
$$ | . . . . . . . . . . . . . . . O . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . 6 . . . . . . . . . . . . . O X . . |
$$ | 8 3 4 . . . . . . . . . . O . O . . . |
$$ | . 2 O O 5 . . . . , . . X O X O O . . |
$$ | . 7 X X O . . . . . . . . X X X O X . |
$$ | . . 9 . X 1 . . . . . . . . . . X O . |
$$ | . . . . . . . . . . . . . . . . . X . |
$$ ---------------------------------------[/go]

I believe the above is Cho's variation

Click Here To Show Diagram Code

[go]$$Wcm50 Switcheroo shocker
$$ ---------------------------------------
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . X O . . . . |
$$ | . . O . X O . . . . . . X O O O O . . |
$$ | . . O X . X . . X , . . X X O X X . . |
$$ | . . . . . . . . . . . . . O X . . . . |
$$ | . . . O . . . . . . . . . O . X . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . X . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . , . . . . . , . . . . . , . . . |
$$ | . . . . . . . . . . . . . . . O . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . O X . . |
$$ | . . . . . . . . . . . . . O . O . . . |
$$ | . . O O 3 . . . . , . . X O X O O . . |
$$ | . . X X O 2 . . . . . . . X X X O X . |
$$ | . . 7 5 X 1 4 . . . . . . . . . X O . |
$$ | . . . . . 6 . . . . . . . . . . . X . |
$$ ---------------------------------------[/go]

And this would be the benchmark diagram, which is 37% better.

This is Cho's variation. I.e., what he played in the game. Thanks to Knotwilg for showing the usual joseki for comparison.

Elf does not indicate a single mistake by Cho. was a mistake, and was a blunder. It cost more because Black could have reversed course and captured . But we humans tend to be consistent, except when we are not. Cho played with the intention of capturing .

_________________
The Adkins Principle:
At some point, doesn't thinking have to go on?
— Winona Adkins

Visualize whirled peas.

Everything with love. Stay safe.

These are not happy times, but I hope everyone is well and reasonably happy, given the circumstances. I have been at home, holding down the fort, for almost five weeks now. It is good to talk with my friends here on L19.

Take care.

_________________
The Adkins Principle:
At some point, doesn't thinking have to go on?
— Winona Adkins

Visualize whirled peas.

Everything with love. Stay safe.

Thanks, Bill!

I'm also home (and working from home) for five weeks. Good thing is: without commuting I have more time for go!

And thanks for your "fuseki analysis"! I always read them with great interest but saldy have nothing to contribute ^^

Wishing the best to you and all of L19 =)

_________________
My "guide" to become stronger in Go

Let us assume the C15 and N3 ajis are siimilsr. Cho's variation is better for W because B does not have a later forcing move on the outside. In the joseki, B has some. We know that 37% is not an absolute number; it simply indicates a clear mistake in the program's opinion.

Personal update.

Going on 8 weeks now. Doing OK. Toilet paper may be delivered tomorrow, we'll see.

In the US, we are told, the food chain is in peril. Without sitdown business, restaurants are not buying food like they have been doing. A potato farmer had tons of potatoes that he could not sell and said that anyone who wanted some could come and get them. I am reminded of pictures of grain rotting by the side of the road during the great depression, as supply outstripped demand before the dustbowl hit. Today, at least, farmers are getting Federal subsidies.

OTOH, the demand for meat is apparently now higher than supply, because processing plants have closed because they have become Covid-19 hotspots. The President has issued an executive order for them to reopen, safeguards or no, damn the virus.

I now believe that I should do my part to reduce the demand for meat by going vegetarian for the foreseeable future.

P.S. Many tons of that farmer's potatoes ended up in food banks, where demand is quite high for food, but funds are low. They have all or nearly all been consumed by now.

_________________
The Adkins Principle:
At some point, doesn't thinking have to go on?
— Winona Adkins

Visualize whirled peas.

Everything with love. Stay safe.

I think you live in California? It seems you've passed the peak one week ago. Probably you will be back to almost normal life before the end of May, except that you will need to wear masks and apply social distancing: avoid crowded places, restrict traveling.

Thanks, jlt.

We shall see what we shall see.

_________________
The Adkins Principle:
At some point, doesn't thinking have to go on?
— Winona Adkins

Visualize whirled peas.

Everything with love. Stay safe.

Stuff like this always strikes me as weird, because in general I don't believe we stopped eating.

I guess the basic principle is that it takes time for the supply/demand to rearrange itself, but it could also showcase how we eat differently at home vs. at restaurants. I.e. it might be that we eat less french fries when home cooking

Also says something about how much food waste/surplus there is, because as far as I know, people are not starving. The calories not eaten from the potatoes must be found in something that would not have been eaten otherwise.

The answer may lie in that food is thrown away all along the food chain, it just happens sooner now. There's less processed and packaged food in our litterbins.