Seki Kotaro has recently made news through becoming the fast ever Japanese pro to progress from qualifying as 1-dan to winning a BIg 7 title (4 years 8 months; the 47th Tengen in Dec 2021, shortly after his 20th birthday).
Comments on games in the Japanese press do not often allude to AI (and graphs are almost totally absent), but comments on Seki's games do have a little more AI seasoning than most. Indeed, he has been described as what me might, in English, call the poster boy for AI. The Japanese phrase for this is 申し子 or moushigo. 申す is an honorific verb for speaking, and might be used for addressing the gods. So a moushigo is a child heaven-sent to a childless couple in response to their prayers. I suspect there is a hidden pun here, too, because the foreign player who is talked about in AI terms in Japan is Sin Chin-seo. It has been suggested that Sin is the human whose play most matches AI play. By coincidence, Sin's surname is 申.
Seki's play is likewise noted as following the AI tramlines, not quite to the terminus, but certainly for a long ride. In Game 4 of the Tengen title match, he as driver with Ichiriki Ryo as conductor, managed a trip of 40 stops before the first glitch appeared. Even then it was a small one, but highly instructive.
Since I am presenting this in my own way, a little bit of background is needed. The position after move 40 was the one below (White has just played L17). Seki made the comment that there was a severe move here according to AI, and as Black (Seki) missed it he got a small disadvantage. In AI terms it was a mistake of 3-4 percentage points, which is inconsequential to us but of concern to a pro. I have shown, unranked, the moves that were considered by my AI. You may care to guess the AI move, and adduce the reasoning, which we look at below.
What I think I have discovered is that whereas traditional go theory is heavily binary (profit/thickness, invade/reduce; attack defence, miai, etc), the theory being developed in the light of AI is about nexuses. Properly, the plural of nexus is nexus (long u in Latin) but I will grit my teeth and talk about nexuses (and nexusology as the theory).
It is my assertion that if you look at a typical position with AI's policy moves marked, as above, you can/should categorise them into three main (Tier 1) nexuses: settling moves, colonising moves and overconcentrating moves. There is a Tier 2, which includes a probes/preparation nexus and a trades/sacrifice nexus, for example. And so on.
Each concept is a nexus because it does not depend on a definition but is rather a network of associations. So settling, for example, covers making bases, making prophylactic defensive moves (e.g. mamori and honte), and settling boundaries (yose). 'Overconcentrating' is a nexus that includes efficiency but also e.g. forcing moves.
Some moves can fall into more than one nexus. I won't say much about that here (I do say a little more in Go Wisdom though that is not yet definitive), but it does add a time element to nexusology in that it can make such moves more urgent. Normally nexusology is not designed to predict the best move. It is rather designed to provide a rational narrative to the commentary on a game. It tries to predict the right area for the best move and the explain the rough reasons for that move. Choice of the exact right move depends also simply on reading, along with the undercurrent of timing.
What I would claim is that people attuned to AI moves would instinctively look at certain types of moves such as those triangled above. Even weakish amateurs would now readily look for shoulder hits, contact plays and centre moves. I believe that pros do the same but on a larger scale. That larger scale is, I think, describable as nexusology. I stress that the terms and categories are my own, and could be quite off-beam, but I have based them in what I have read.
Now back to specifics. What was so interesting for me about the right play for move 41 above was that Seki did not really miss it. He actually played it, but on move 51. His mistake was more a matter of timing. The right move could be defined as coming in to the overconcentrating and settling categories, but so could Seki's move. It is my strong impression that the best young pros of today are not having much problem seeing the the candidate moves. Their problems are with timing them.
Let us now look at Seki's comments in that light. The following is the AI recommendation. Seki's actual move was M16.
Attachment:
Capture1.JPG [ 44.46 KiB | Viewed 7972 times ]
Seki's 'headline' comment on Black 1 (which he did play on move 51, I repeat, though the reasoning differed by then) was that, "It's rather difficult for a human to see it, but given the situation on the tight side, it seems to be the most urgent point." I infer from this, as I have already indicated above, that the flaw in his nexusology is not really a matter of noticing the move but a matter of timing or urgency.
Seki then goes on: If White 2 submits at 5, Black can be satisfied with then playing the jump to 'a'. That being so, I would want definitely to play the nobi for White 2, but then Black 3 and the hane 5 are severe. After White cuts at 6, Black 7 and 9 are a tesuji. They make miai of b and c [S7]. White has been suckered into this sequence. Therefore, White cannot resist Black 5 with 6 here but will have to do something like block at White 1 below." (10 at 1)
Attachment:
Capture2.JPG [ 43.71 KiB | Viewed 7972 times ]
"After Black connects at 2, White makes a prophylactic move (mamori) on the right side at 3, but Black's hane next at 4 is very punishing. White has to defend submissively [ukeru as opposed to mamoru] and ends up shapeless. When he guilelessly plays 5, Black cuts at 6 and White 7 to 11 produce shapeless mess. In contrast, Black has very nice shape on the right side. The division of spoils favours him, doesn't it? I could understand that Black's contact play 1 in the first diagram was the urgent point once the AI showed it to me, but with just a cursory look at the position I didn't really register it."
In connection with that last remark, he said elsewhere that he prefers 8-hour games to 5-hour games. THta bucks the trend a bit. I wonder whether it indicates that the new breed of pro relaises they need more game-time to get to grips with the complexities nexusology implies.
In that separate interview, Seki says some very interesting things about AI percentages. There's not enough life on L19 to justify me spending the extra time on that, but if you want to hunt it out it's in Go Monthly 2022/2.