See my separate threads on AI verdicts on Jowa, Shusaku and Dosaku as compiled by Ohashi Hirofumi.

Ohashi has now added a very brief washing-up article on his mini series of using Golaxy to assess players of the past.

He admitted to great nervousness before the series began, expecting to demolish fans' respect for these legendary players. In fact it worked out the opposite way, and with the bonus that the bot actually seemed to confirm our traditional human perception of the strengths of each player.

But one traditional view that now has to be challenged is that the old pros were super strong in the endgame. Golaxy showed consistently that it was possible to make moves in the middle game and endgame that could impact on the game as a whole and which were therefore better than just making territory-settling boundary plays.

This not only calls into question the long favoured Japanese style of soba go, or compromise go or quid pro quo go. Ohashi believes it is in this area that Japanese players need to make changes in order to challenge Chinese and Korean players.

In fact I recall Wang Xi making this point in a long and detailed article in Weiqi Tiandi long before AI bots were even a gleam in the eye. He specifically trashed the concept of soba go and specifically said the Chinese and Koreans now went for the percentage play. Recent history seems to have justified that view. It seems that greed is good in go.

Of course playing the percentages only works if you know how to work out the percentages...

When I was first learning to play go I was, as probably many of us were, told that greedy play was bad. When weak players play greedily against a stronger player, the greedy player often loses. I was also told that go is a game of balance and if you try to keep your opponent from getting anything you will lose. The kind of greedy play often exhibited by weak amateurs is not the same as John Fairbairn cited above. John described the Korean and Chinese approach to go as playing the percentages. I believe that the win rates given by AI bots are not quite exactly the percentage chances of winning. I'm not sure what they are exactly, maybe the percentage of winning in the playouts? Could the percentage play John mentioned might be just playing the most efficient moves? I'm sure that's what pros in general try to do.

I thought that the idea that top players played nearly perfect endgames was confined to the 19th century, when games could take forever.

It may well be that Golaxy, which has an idea of territory or area, plays a better endgame than other top bots, but the question of impacting the game as a whole is not very precise. And "just making territory-settling boundary plays" is an unfair characterization of endgame technique. Few of my endgame problems, even though all of the plays are "territory-settling boundary plays", and the problems are pretty easy, deserve that description, IMHO.

I wonder how Golaxy would do with this problem, my revision of one of Berlekamp and Wolfe's problems in Mathematical Go. No komi, but Golaxy can handle that, right?

Click Here To Show Diagram Code

[go]$$Wc White to play and win
$$ ---------------------------------------
$$ | . X . . . O . . . . . . . X . . . O . |
$$ | . X . . X O O O O X X . X X O . . O . |
$$ | X X X X X O . X O . X . O X O O O . . |
$$ | . O O O O O O X X , . X . X X X O O . |
$$ | . O . O . . O O X X . . X . X X X X X |
$$ | . O O . O . . . . X . . X O X . . . . |
$$ | . . . . O X O O O X X . X . . . X X . |
$$ | O O O . O . . O . X . X X X X X X O O |
$$ | X X O O O O O . O X . . X . O O O . . |
$$ | . X X X X . O O O X X X O X O , . O . |
$$ | . . X . X . X X O O O O O O O O O . . |
$$ | . . . X X . . . X X O . . . . . O O O |
$$ | . X X . . X X X . X O . . O O . . . . |
$$ | . X . X X O X . X X O O . O . O O O . |
$$ | . X X X . . X X X O O . O O O O X X X |
$$ | O O O O . X X . X X O . . O . , . X . |
$$ | . . . O . X . . . . . O . . O X X X X |
$$ | . O . O O X X X X X X O O . O O X . . |
$$ | . . O . . O . . . . X X O . . O . . . |
$$ ---------------------------------------[/go]

You need to read to depth 29 to reach an "obviously" won position, depth 69 to where only dame are left, but the first few plays are obvious and after that there are only a few plays worth considering at each turn. And all of the plays are just territory-settling boundary plays. Piece of cake for a superhuman bot, no?

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

Visualize whirled peas.

Everything with love. Stay safe.

gowan: the kind of percentages I'm talking about as characteristic of soba go are (as far as I know) nothing to do with win rates.

In golf each hole has a par score, which represents something like an estimate of how many strokes the generality of golf pros would, on average, take to complete that hole.

Soba go is like playing par golf.

But pros who want to actually win tournaments know they have to go beyond par and make birdies. That means they calculate the odds, for themselves, of overhitting a drive or taking a risky line to the path, so that they can get a birdie. They know there is a risk involved. They might end up with a bogie. But the best players can feel confident in their own play and convince themselves that the chances of making a birdie - the percentages - are better than making a bogie. They will further refine that gamble on the basis of the situation in the tournament and how their opponents are doing.

In go, Chinese and Korean players, full of confidence, are making the same sort of attempts to get birdies. Too many Japanese players are stuck playing for par. These percentages (not precise figures, of course, so maybe not the ideal term) apply to local situations, not the overall game. A game can thus seen as a series of "holes." A series of birdie opportunities. If you get more birdies than pars you can win easily against a typical Japanese player.

I doubt that AI can tell us much about all that. It's to do with humans' constant efforts to strike a balance between safety and risk taking. You can improve your chances of taking risks successfully by improving technique, fitness, experience, etc. But it still boil down to a gamble at the OK Corral.

Bill: you've changed the topic, really. My fault for using a sloppy term like territory-settling. Maybe I should have said aji-fixing or whatever, but I was trying to avoid the word 'thick' for reasons you are aware of more than most. And also, I did say middle game and endgame. We are talking about live games (in every sense), not puzzles.

I went looking up https://senseis.xmp.net/?Souba to understand the point made here.



"Soba go" then means, "to play the best sequence in each position" and the traditional assumption is that this is also the best thing to do in the situation. If we undermine that assumption - and call this "playing the percentages" - this means that in many situations it is preferable to choose a more adventurous line than the "best sequence in that position" which may have implications beyond that position (more aji, a source of ko threats, a ko itself, ...) but overall that extra risk is offset by the extra gain.

Is this what you mean with "greedy go pays off"?

Well, you did start off talking about the presumed excellence of pros of yore in the endgame. BTW, I did check out Elf's commentary on Shusai's famous 8 hour tank to read out a 2 pt. win in the endgame. Elf suggested other plays from time to time, no surprise there. Most of them, I think, did not alter the result, but a couple might have been improvements.




Truth to say, the first thing I thought of when I read your post was Sakata's discussion of thick plays in the endgame. But I regarded them as plays that "impacted the game as a whole".

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

Visualize whirled peas.

Everything with love. Stay safe.

I really thought it was the same kind of phrase as "spaghetti code"...

Take care

_________________
一碁一会

As the great, and very witty bridge author, Victor Mollo wrote, "Par is an unworthy goal."

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

Visualize whirled peas.

Everything with love. Stay safe.

Just don't play subpar in your attempts to overcome par

_________________
be immersed

Maybe ... atsui?

No really, I love this post - so back to my question about souba vs greedy go.

This is not my understanding of soba. I see it more as "good enough" or "reasonable" and a fairly standard and equitable exchange. Soba is never going to win move of the year. I think I read some article by John in GoGoD alluding it to accounting, lose a bit here, gain an equivalent bit there, so the end position is as good as the start position. So you maintain a balance and then if your opponent makes a mistake you take a lead, and then you keep playing soba to maintain the lead. You are not pushing the boundary of unreasonableness or overplay seeking to proactively take the lead which comes with the risk of getting punished if your move was indeed too much (which you probably don't even know, just have a feeling). The traditional Japanese style is the risk-averse soba, whereas someone like Lee Sedol is the Korean risk-taking trying to win, not just trying not to lose.

I also recall some quote from Hane Naoki about how he tries to play the 80% move (number not guaranteed, but it was a fair bit less than 100), where 80% doesn't refer to a win%, but 100% would be the most efficient and totally optimal move (so super-strong-bot win % remains unchanged at whatever it is between 0 and 100) but possibly really complicated and chances to backfire if you make the slightest mistake. Trying to find the boundary of the 100% move, and not trying to get even more, let's call it the 110% move if your opponent doesn't punish it but actually it is an overplay so it could end up as a 20% move, is very hard, so Hane is content to stay well away from it and play "good enough", whereas the Korean/Chinese (and Go Seigen) and now AI style is going for more efficiency and getting closer to that 100% line.

There was an interesting example of this on reddit recently, with someone asking for clarification about this position and explanation in Kageyama's "Lessons in the Fundamentals of Go" (taken from one of his games).

Click Here To Show Diagram Code

[go]$$B
$$ +---------------------------------------+
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . X X X . 1 . . . . . . . . . O . . |
$$ | . . O X O O . a . , . . . . O , X . . |
$$ | . . O O X O . b . . . . . . . . . . . |
$$ | . . O X X X X . . . . . . . . . . . . |
$$ | . . O X . . . . . . . . . . . . . . . |
$$ | . . . O . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . , . . . . . , . . . . . , . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . X . . . . . , . . . . . , . . . |
$$ | . . . . . . . . . . . . . . . O . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ +---------------------------------------+[/go]

Kageyama writes:


Even before you ask an AI and it shreds Kageyama's argument, I find it rather dubious. First of all I now find the endless partition of go thinking and skill into ama vs pro a bit tiresome and inaccurate as many amateurs are stronger than pros (and in thinking not just oh this pro is old and can't read anymore but has a superior way of thinking to this strong at reading crude amateur 7d), but as the book was original called Ama vs Pro or whatever in Japanese it's understandable. I bet there would be some Japanese pros even back in 1978 who wouldn't like 1 and prefer the greedy but bad aji 'a', maybe Sakata?

Unsurprisngly, many bots (I asked LZ 234, LZ 15b, MiniGo cormorant, Elf v2) strongly prefer Kageyama's bad 'a' over his 'only move' 1, and I am strongly inclined to believe them over him that is objectively a better move. This seems to me to be a typical example of striving for optimial efficiency, rather than accepting a slightly slack result that minimises bad aji and the chance of you messing up later. If 1 really is the best move, Kageyama-agreeing pros can smugly say "I didn't even need to read the bad aji sequences which shows that 'a' is too much, just based on my experience/intuition and judgement I can discern that the future problems it leaves are not worth the extra points" (and less good forcing moves! very important negative of the net is white b next). However, I suspect a lot of Korean pros would want to play 'a' and the philosophy is "I want this better result, and I tried reading a way it is bad but couldn't find it, so go on, you have to prove to me it's not good or else I get more". So Kageyam's net is like Hane's 80%, avoid risk for a result he judges 'good enough'. The bots say it's not good enough because they can detect a e.g. 0.3 points loss on move 40, and want 100% efficiency.

P.S. on a personal note I too like to strive for 100% efficiency, and spend a lot of time thinking about such interesting finer points. So if I am successful in this I'm quite often leading by move 70. But it's tiring and leaves me short of time so I mess up later and lose, as in the first game of the 2015 British Championship. I was very dispirited by that loss, so the next game I played more 'going through the motions', not really trying to win, just play some moves, try not to lose (somewhat soba-ish), and against my fellow 4d opponent that was good enough to win. So although soba's not going to win any international pro tournaments these days, if us weakies can learn to emulate it it's good enough to win all of the games we play. And rationing your expenditure of mental resources so you can play Hane's 80% all game instead of 100% to start and 0% blunders at the end surely increases you overall chances to win the game.

FWIW, my impression about bot style in general vs. human style in general is that the bots play more flexibly than humans. They may play more efficiently because they play better, but I think that's a different question. And if you are trying to win, well, good enough is good enough. It may be better in some sense to offer a possible furikawari where the results are unclear than to nail down territory, but if nailing down territory nails down a 5 pt. win, why not? Remember bots are trained on self play, where both players may be drawn to the furikawari, so they may not have learned to play against opponents who nail things down. (To be clear, I actually think that human play is not flexible enough, but I also would have more confidence in bots' play if they trained against a variety of styles. )



Indeed.



How strong is their preference? 7% or more? How many playouts? At least 100k for each of these two plays?



If you mean 0.3% points winrate difference, I agree that the bots should pick the best play they can, but I would not claim that the higher rated play is more efficient. There is too much uncertainty for that. But it's a good enough play.

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

Visualize whirled peas.

Everything with love. Stay safe.

With 100k playouts, KataGo thinks that a has a winrate of 43.7% and an estimated score of -1.8 (with komi at 7.5, I think), while has a winrate of 40.0% and an estimated score of -2.9.

Interesting. Thanks.

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

Visualize whirled peas.

Everything with love. Stay safe.

I'm not sure it is correct to generalize from this one position. I saw many cases of the opposite as well, where bots happily traded (in open games) a few point of immediate profit for less aji (thus future flexibility). IMO it's just that in this particular case they see the risk smaller than the gain (not the extra points only I guess but more central control maybe).

jann, yes that's a fair point: sometimes bots play the tighter move for less profit but better aji, because they evaluate the bad aji in those cases as being too much of a negative. If I could (facetiously) put words into Kageyama's mouth: he is saying "because 1 leaves bad aji and it is too difficult / I am too lazy to read out possibly downsides of that aji which may come far in the future of many different possibilities, and evaluate the pros and cons of that vs the aji/forcing moves left by the net which surely captures the cutting stones, I am not even going to think about it, and be proud in my ignorance (and because I'm a pro you should trust me)".

Bill, here's a screenshot of Lizzie with LZ #234 after ~100k playouts. You can see the distribution of playouts is very sharp: 100k at 48.8% for 'bad' 1, under 1k for every other move considered and just 9 for a. So the error on its 42.3% (-6%) is large, playing that move and giving 100k playouts gets a winrate of 37.9% (-11%).

Here's my commentary/interpretation of LZ 234's opinion on some continuations, to help understand why it thinks net is bad.

Following Kageyama's net. LZ's instinct (low playouts) wants to peep from the outside, and this remains strong 1st choice at 100k playouts, though the expected continuation does change. The early idea was for 4 to be h17 (mine too), but then it changes to j16, a move closer to the top right corner and thus helping a bit more there. To start with it thought black should immediately answer 4 at h16 (36.9% with 30k) giving white the h17 atari, but after several 10ks playouts it decides that black is slightly better to resist and attack on the left side first with 5 (37.9% at 56k) because that's more sente. That white needs to take gote with 8-10 is indeed rather painful (the 'need' is not 100%, but pulling out the 3 stones for 8 is -10% and black gets e12 seal in sente so e14 get strong so cutting is less useful anyway).

Click Here To Show Diagram Code

[go]$$Bc LZ punishing Kageyama's net
$$ +---------------------------------------+
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . X X X . 1 . . . . . . . . . O . . |
$$ | . . O X O O . . 4 , . . . . O , X . . |
$$ | . . O O X O 3 2 . . . . . . . . . . . |
$$ | . . O X X X X . . . . . . . . . . . . |
$$ | . . O X . . . . . . . . . . . . . . . |
$$ | . . . O . . . . . . . . . . . . . . . |
$$ | . 0 6 . . . . . . . . . . . . . . . . |
$$ | . 8 5 7 . . . . . , . . . . . , . . . |
$$ | . 9 . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . X . . . . . , . . . . . , . . . |
$$ | . . . . . . . . . . . . . . . O . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ +---------------------------------------+[/go]

Black's fix at h17 avoids giving white the atari there, and white then take the big opening move of a shimari (62.5% at 20k). Continuing in top right with q16 is not bad either (62.2 at 1.5k). Black continues there, white extends on the top and we can appreciate the h15 and j16 stones as useful moves bolstering this group, cover fire. They also served a purpose in that white was confident to play 12 as tenuki to shimari and not being scared of a black pincer at m16 instead of s17, as they provide some support in a fight that could follow.

Click Here To Show Diagram Code

[go]$$Bcm11 LZ punishing Kageyama's net contd.
$$ +---------------------------------------+
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . X X X . X 1 . . 6 . . . . 4 O 3 . |
$$ | . . O X O O . . O , . . . . O , X . . |
$$ | . . O O X O X O . . . . . . . . . . . |
$$ | . . O X X X X . . . . . . . . . . . . |
$$ | . . O X . . . . . . . . . . . . 5 . . |
$$ | . . . O . . . . . . . . . . . . . . . |
$$ | . O O . . . . . . . . . . . . . . . . |
$$ | . O X X . . . . . , . . . . . , . . . |
$$ | . X . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . 2 . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . X . . . . . , . . . . . , . . . |
$$ | . . . . . 7 . . . . . . . . . O . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ +---------------------------------------+[/go]

Given that LZ thought black could interpose the attack on the left with 5, I had a look what LZ thinks of black not immediately peeping the net but defending there. Here's LZ's view showing that it has a strong preference for immediate peep, but the extension and tiger mouth on the left there are the 2nd and 3rd choice moves, though a long way behind at 2k to 112k for the peep (and tiger mouth can amusingly revert with black d10, white h15).


So if extend (-3.4%), LZ wants to immediately clamp, taking advantage of the fact white extended further trying to be more efficient that tiger mouth to get a good exchange (white resist with e12 extend out is not unplayable, -3%) and then pincers on top. White now tries to get the same peep, but we get a clue why LZ wanted to peep immediately: with m16 in place already black can now reasonably resist with h14 instead of g15. Timing is so important in being able to make beneficial exchanges without the opponent reasonably resisting, and is probably behind bots tending to like exchanging early because, like here, they judge that they can't get it later. As black didn't defend, white attaches at 8 and then 10, and we have ourselves a complicated fight.

Click Here To Show Diagram Code

[go]$$Bc What if extend on left?
$$ +---------------------------------------+
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . X X X . 1 0 . . . . . . . . O . . |
$$ | . . O X O O . . . , 8 5 . . O , X . . |
$$ | . . O O X O . 6 . . . 9 . . . . . . . |
$$ | . . O X X X X 7 . . . . . . . . . . . |
$$ | . . O X . . . . . . . . . . . . . . . |
$$ | . . 4 O . . . . . . . . . . . . . . . |
$$ | . . . 3 . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . , . . . . . , . . . |
$$ | . . 2 . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . X . . . . . , . . . . . , . . . |
$$ | . . . . . . . . . . . . . . . O . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ +---------------------------------------+[/go]

Further insight can be gained from asking what LZ would do if white simply tenukid to shimari after the net (-17%). Now black doesn't just attack with c12 checking extension, but b11 2nd line base attack! Such a move would have been overplay following white h15 peep, because in that case after black steals the base on the left white saves the 3 cutting stones so black f14 group is floating, so white left group being weak has a black weak group to pressure too in exchange.

Click Here To Show Diagram Code

[go]$$Bc What if tenuki?
$$ +---------------------------------------+
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . X X X . 1 . . . . . . . . . O . . |
$$ | . . O X O O . . . , . . . . O , X . . |
$$ | . . O O X O . . . . . . . . . . . . . |
$$ | . . O X X X X . . . . . . . . . . . . |
$$ | . . O X . . . . . . . . . . . . . . . |
$$ | . 5 6 O . . . . . . . . . . . . . . . |
$$ | . 3 4 . . . . . . . . . . . . . . . . |
$$ | . . 7 8 . . . . . , . . . . . , . . . |
$$ | . . 9 0 . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . a . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . 2 . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . X . . . . . , . . . . . , . . . |
$$ | . . . . . . . . . . . . . . . O . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ +---------------------------------------+[/go]

So that's how LZ as white (and then black) would punish Kageyama's net. How about what happens with the bad aji with 'greedy' (or efficient) outside move? LZ does immediately want to turn. My first idea was for black to jump down to 2nd line h18, but LZ thinks j17 better (48.7% at 71k vs 44% at 60 for h18). So why is jump worse? Because even though it captures the white stones white gets a nice kikashi at j17. Actually 5 here is slack, black can play f18, white wedges at g18, black then connects and it's complicated, but for the sake of making a simple settled position to compare black ends this at 42%, compared to 38% for the net. White getting b17 in sente is some nice extra eyespace for that group and j17 peep is some use, but not as useful as the h15 and j16 forcing moves against the net. Plus remember this is black playing my bad move of h18 instead of LZ's favoured j17, though I imagine Kageyama might have glance-read this kind of line as an example of the 'bad aji not working yet' even if he professes to have not given it a second thought.

Click Here To Show Diagram Code

[go]$$Bc Greedy then jump
$$ +---------------------------------------+
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . 7 . . . 9 . 3 . . . . . . . . . . . |
$$ | . 6 X X X 2 . 5 4 . . . . . . . O . . |
$$ | 8 . O X O O . 1 . , . . . . O , X . . |
$$ | . . O O X O . . . . . . . . . . . . . |
$$ | . . O X X X X . . . . . . . . . . . . |
$$ | . . O X . . . . . . . . . . . . . . . |
$$ | . . . O . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . , . . . . . , . . . . . , . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . X . . . . . , . . . . . , . . . |
$$ | . . . . . . . . . . . . . . . O . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ +---------------------------------------+[/go]

So how is LZ's kosumi better than my jump? If white still dies then you got more points and stopped white getting j17 peep, so that would obviously be better. But white isn't dead now, but ko-ish. This is disquieting: a complicated sequence that is hard to judge and the kind of thing soba go tris to avoid, but bots relish.

Click Here To Show Diagram Code

[go]$$Bc Greedy then kosumi?
$$ +---------------------------------------+
$$ | . . . . 9 0 . . . . . . . . . . . . . |
$$ | . . . 5 4 . 6 . . . . . . . . . . . . |
$$ | . . X X X 2 . . 3 . . . . . . . O . . |
$$ | . 7 O X O O . 1 . , . . . . O , X . . |
$$ | . . O O X O . . . . . . . . . . . . . |
$$ | . . O X X X X . . . . . . . . . . . . |
$$ | . . O X . . . . . . . . . . . . . . . |
$$ | . . . O . . . . . . . . . . . . . . . |
$$ | . . 8 . . . . . . . . . . . . . . . . |
$$ | . . . , . . . . . , . . . . . , . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . X . . . . . , . . . . . , . . . |
$$ | . . . . . . . . . . . . . . . O . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ +---------------------------------------+[/go]

Here's how LZ sees the ko fight could continue. Ignoring 12 is -20%, it's almost a picnic ko for white. 13 extend instead of corner hane seems to be minimizing white's big threats because black can't afford to lose the ko, but hane is <1% worse in winrate and might revert anyway. Black concedes the ko with connect, so white gets some profit on left side and the top group isn't dead yet.

Click Here To Show Diagram Code

[go]$$Bcm11 Don't play go if you are scared of ko (14 retakes)
$$ +---------------------------------------+
$$ | . . . 5 X O . . . . . . . . . . . . . |
$$ | . . . X O 1 O . . . . . . . . . . . . |
$$ | . 7 X X X O . . X . . . . . . . O . . |
$$ | . X O X O O . X . , . . . . O , X . . |
$$ | . 6 O O X O . . . . . . . . . . . . . |
$$ | . . O X X X X . . . . . . . . . . . . |
$$ | . . O X . . . . . . . . . . . . . . . |
$$ | . . . O . . . . . . . . . . . . . . . |
$$ | . . O . . . . . . . . . . . . . . . . |
$$ | . . . , . . . . . , . . . . . , . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . 0 . . . . . . . . . . . . . . . . |
$$ | . . 8 3 . . . . . . . . . . . . . . . |
$$ | . . 2 X . . . . . , . . . . . , . . . |
$$ | . . 9 . . . . . . . . . . . . O . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ +---------------------------------------+[/go]

The lower left resolves, and white j18 h17 to settle top group could be coming soon. Black is keeping the best win% he can get of 48-49% in these lines.

Click Here To Show Diagram Code

[go]$$Bcm21 ko line cont.
$$ +---------------------------------------+
$$ | . . . X X O . . . . . . . . . . . . . |
$$ | . . . X O . O . . . . . . . . . . . . |
$$ | . X X X X O . . X . . 4 . . . . O . . |
$$ | . X O X O O . X . , . . . . O , X . . |
$$ | . O O O X O . . . . . . . . . . . . . |
$$ | . . O X X X X . . . . . . . . . . . . |
$$ | . . O X . . . . . . . . . . . . . . . |
$$ | . . . O . . . . . . . . . . . . . . . |
$$ | . . O . . . . . . . . . . . . . . . . |
$$ | . . 6 5 . . . . . , . . . . . , . . . |
$$ | . . . 7 . . . . . . . . . . . . . . . |
$$ | . . 8 . . . . . . . . . . . . . . . . |
$$ | . . 2 . . . . . . . . . . . . . . . . |
$$ | . . O 1 . . . . . . . . . . . . . . . |
$$ | . . O X . . . . . . . . . . . . 9 . . |
$$ | . . O X . . . . . , . . . . . , . . . |
$$ | . . X 3 . . . . . . . . . . . O . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ +---------------------------------------+[/go]

Kageyama does say that white turn is disquieting even if doesn't work yet, so he could be afraid of tenuki and the aji biting him in the arse later. It's hard to pick a particular sequence of play to illustrate this and test if that judgement was good, but in the real game Kageyama defended on the left at c10 (which means black b16 isn't sente, so white f17 more pressure on corner in future) and then black continued in the upper right, allowing white to extend at m17. That f17 turn is definitely getting more disquieting now, so if black did play the greedy move he should play differently to handle it.

Click Here To Show Diagram Code

[go]$$Bc Playing rest of board like real game
$$ +---------------------------------------+
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . X X X . . . . . . 8 . . . 4 O 3 . |
$$ | . . O X O O . 1 . , . . . . O , X . . |
$$ | . . O O X O . . . . . . . . . 7 . 5 . |
$$ | . . O X X X X . . . . . . . . . 6 . . |
$$ | . . O X . . . . . . . . . . . . . . . |
$$ | . . . O . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . 2 , . . . . . , . . . . . , . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . 9 . . . |
$$ | . . . X . . . . . , . . . . . , . . . |
$$ | . . . . . . . . . . . . . . . O . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ +---------------------------------------+[/go]

So what's LZ's view on the above. 2 is -10%, should turn immediately as discussed above. 3 is then -13%, should be L17, allowing white s16. This obviously is concerned with nullifying the aji of f17 (black would now reply at f18). I could well imagine Kageyama and some other pros might not like the fact black spends 2 moves to fix the top here, instead of the 1 with the net. But the question is 1 move with net, and the useful forcing moves for white it leaves at h15 and j16, actually better than spending 2 moves on it for a position with more territory (l17 obviously big on its own and means after white s16 black can use it when activating r16) and leaving less useful kikashi for opponent. If black 3, white 4 obviously ok as urgent local shape. 5 is then a little bad (-3%), L17 or m17 again better. 6 should then be f17, and there's lots of choices for how black can continue. One interesting one is g18, then white e18 hane, f18 cut, b17 hane in corner and black d18: white sacrifices the 4 stones for b17 not getting blocked.

So the summary from LZ in this hypothetical future is: yes 1 on outside leaves bad aji, but net leaves too good forcing moves for opponent, so better to leave the aji, be mindful of it and potentially spend another move on it soon, than accept the slack result of net.

Many thanks for an interesting and instructive analysis.

The procedure the bots use where there is a great disparity in playouts between candidate plays is fine for finding good enough plays. But consider that it was quite possible for Kageyama's play to gain around 4½% with 100k playouts instead of losing that much. Then it would only have been a 2% underdog, surely within any reasonable margin of error. And it is even possible for it to become top dog, isn't it? (That happened when I played around with Deep Leela, BTW. OC, Deep Leela is a weaker player.) That's why I would like someone to develop an analyst instead of a player. But there is no glory in that, eh?

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

Visualize whirled peas.

Everything with love. Stay safe.

That was just a quick look on my laptop, only a few thousand. With 100k Elfv2 agrees with LZ that Kageyama's bad move is better than the net (and with immediate peep and kosumi continuation), but decides another move is even better (52.3% vs 50.3% vs 35%). Black goes even bigger with k17, white turns f17 (j16 shoulder hit is 2nd choice, then black plays g16 and white j17 and black attacks left at d10, so k17 can basically be seen as bait to make black capture the cutting stones in sente so he can attack on left), then casts the big surround of 3. Interesting white doesn't then try to live with e18, which is possible but as he'd have to answer black b16 at c11 in that sequence anyway, and it would make black stronger on the outside with exchanges like j17 for k16, just defends there immediately, lets black kill the stones and then forces from the outside with 6, which si screening kikashi against black's extension to a aiming at b in the shape white plans to build at the top right.

Click Here To Show Diagram Code

[go]$$Bc
$$ +---------------------------------------+
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . 5 . . . 7 . . . . b . . . . |
$$ | . . X X X 2 . . . 1 6 . a . . . O 0 . |
$$ | . . O X O O . . . , . . . . O 8 X . . |
$$ | . . O O X O . . 3 . . . . . . . 9 . . |
$$ | . . O X X X X . . . . . . . . . . . . |
$$ | . . O X . . . . . . . . . . . . . . . |
$$ | . . . O . . . . . . . . . . . . . . . |
$$ | . . 4 . . . . . . . . . . . . . . . . |
$$ | . . . , . . . . . , . . . . . , . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . X . . . . . , . . . . . , . . . |
$$ | . . . . . . . . . . . . . . . O . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ +---------------------------------------+[/go]

Many thanks, Uberdude!

Fascinating stuff, eh?

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

Visualize whirled peas.

Everything with love. Stay safe.

And here is MiniGo's mainline at 200k, black around 48% throughout. So it too likes Kageyama's greedy 1 (and net bad and punished with immediate peep h15), but there is an interesting difference in that it wants to play 3 in corner before kosumi at 7. There is a reason for this, and it's the tesuji at 8. Having to fall back at 9 is annoying, but if you block at c19 then white trades with b17 atari, e19 capture, b18 extend, f18 capture: white is happy to get corner profit in sente and b16 now dumb.

Click Here To Show Diagram Code

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

This kind of 2nd line crawl to avoid death is something humans tend to assume is bad, but MiniGo says white is fine at 53%.

Click Here To Show Diagram Code

[go]$$Bcm11
$$ +---------------------------------------+
$$ | . . 3 O . . . 6 . . . . . . . . . . . |
$$ | . X . X O . O 5 4 8 . 0 . . . . . . . |
$$ | . . X X X O . 7 X . 9 . . . . . O . . |
$$ | . X O X O O . X . , . . . . O . X . . |
$$ | . . O O X O . . . . . . . . . . . . . |
$$ | . . O X X X X . . . . . . . . . . . . |
$$ | . . O X . . . . . . . . . . . . . . . |
$$ | . 1 2 O . . . . . . . . . . . . . . . |
$$ | . . O . . . . . . . . . . . . . . . . |
$$ | . . . , . . . . . , . . . . . , . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . X . . . . . , . . . . . , . . . |
$$ | . . . . . . . . . . . . . . . O . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ +---------------------------------------+[/go]