Way back in 1985, the now defunct Igo Club, which used to be my favourite magazine, presented an article which asked where to play an erasing move in the following position. It was from a game by Takemiya Masaki which I either haven't got or yet done for the GoGoD database. I'm too old/lazy to climb into the loft and rummage through lots of boxes of magazines to refer to the original article (the game is apparently from 1985, but the opponent is not specified).
It may have been just a next-move problem then, but a new article now - part of a series coordinated by Hirata Tomoya - asks Takemiya and young pros how far they would dare enter White's moyo as an erasing move. Obviously the focus was quite different in 1985 - go AI wasn't even a gleam in the eye - and the article raises the interesting point whether simple "next-move" questions are always appropriate. There are plenty of positions that suggest more than move and the way to discriminate depends on the flow or the "story" of the game. (The Japanese text uses the English word "story" but "narrative" is probably better English.)
But Hirata now asked several young players where to play with a view to seeing whether there were differences between Showa and Reiwa (i.e. pre-A and AI generation players). As I say, I have declined to hunt up the original, but Takemiya's own Showa sequence was Black A, White B, Black C. We all know that this vague sort of move is the sort that gets highlighted in commentaries, so we may want to infer that Takemiya was more a than a little pleased with it. But that was then - his Showa intuition. His Reiwa intuiton has changed.
Before you read on you may wish to make your own guess, but make sure it's backed by a positional judgement first. Maybe you'd want to choose both a Showa and a Reiwa move
There may be a flaw in the methodology in that there is no mention of komi. The 1985 game would have been played with, at most, 5.5 komi. But Hirata spotted, just like Lizzie, that Black is in dire straits and so needs to wrench control of the game in some way. A quiet erasure is not enough, but one that is too deep (an invasion, really) in White's strong area is courting disaster. It seems to be taken for granted that Black's move does have to be inside this moyo, and Lizzie certainly agrees that this is the main area but she also gives close scrutiny to several moves on the left side.
Reiwa Takemiya now prefers the forceful shoulder hit at A, as does young player Fukuoka Kotaro 1-dan (aged 13). Fukuoka's view was that things are easy for Black if White answers on the third line as Black keeps pressing on the fourth line, and if White caps instead (a standard response) Black can achieve shinogi. Ah, the blithe confidence of youth! (He had his eye on F as a key move.)
Takemiya only mentioned White's third-line response, but instead of Fukuoka's forceful subsequent play, he showed only a vague jump out to the centre. He was actually somewhat surprised to be told he'd played as in the first diagram 34 years ago!
Ueno Asami 3-dan got the evaluation right - she'd prefer to be White - and suggested B for Black. Her strategic thinking seemed to be that w White surrounding move on the right side would out the game out of sight for White, so an erasing move tout court was required. But in intuition terms her first thought was the shoulder hit at A. She eschewed that because a White cap would make her too nervous, especially because of the White wall (but which wall? - answer at the end).
Onishi Ryuhei, 4-dan and rising fast (youngest ever Shinjin-O; he's 19), took a rather different strategic tack. He too obviously sensed Black was n trouble and so wanted to cause confusion, so he opted for Black C, expecting then White D, Black E. He felt this gave Black options of messing around on the upper right side while also aiming at the cut at G. But actually, his initial intuition was the same as Asami's - shoulder hit at A but spooked by a White cap.
My version of Lizzie preferred the shoulder hit. It didn't even list Takemiya's Showa move as a candidate. No surprise there. But what might surprise some is that when this Showa move was forced upon Lizzie, she didn't bat an eyelid and gave the same win rate as before!
This latter phenomenon (rating unconsidered moves highly) is too common - troubling even - to ignore. It needs a name so we can talk about it more. I think it was Bill Spight who first noticed it, and is certainly pointing it out most often, so I propose we call it Spight Analysis, or something like Spight Retrospective Analysis. When we use this tool, human pros can usually be shown to be performing very often only a whisker away from AI-bot level.
It also suggests to me that people like Taemiya may have allowed themselves to be swept along by the fashion for AI-type moves. Maybe he ought to have had more confidence in his original judgement?
