Being a fan of novelties and fun items like in GoGoD's New In Go, I thought I'd mention a new position I looked into. I'd be happy to hear more thoughts on this.

In game 5 of the 46th Kisei, challenger Ichiriki Ryo (W) played an interesting set of moves (W18 and W20) against Iyama Yuta (B). I thought this the pincer and keima were a neat follow up to the press in the upper right corner but I assumed that this position was just new to me until I read the Yomiuri commentary by Mutsuura Yuta 7 dan which said that W20 was White's kufuu (invention/game plan).

As background, it took the game 25 minutes to get to B17 and then Ichiriki spent 15 minutes on W18. Iyama spent less than a minute on B19. Then Ichiriki respectfully waited 2 seconds before dropping W20, bowing, and quietly leaving the room. The AI score on stream stayed even with no change in percentage.
Nihon Kiin live stream
Yomiuri commentary

Click Here To Show Diagram Code

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

I looked for similar positions and found some games with a different order of moves and only a single game where this sequence was played in a game between Fujita Akihiko and Yoda Norimoto, but with a dissimilar board. Interestingly, Ichiriki and Iyama had a different game with a similar position in a different sequence.

Here is how the actual game progressed:

Click Here To Show Diagram Code

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

During the game, the newspaper commentator thought it might playout like this instead. I think White would be happy with this. I wonder why this would not have worked. This is how I would play White or Black myself, though 5 would be the simpler 1 space jump.

Click Here To Show Diagram Code

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

In the post game newspaper commentary this variation was shown. Enclosing and building a moyo seems too good.

Click Here To Show Diagram Code

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

The Nihon Kiin net commentators (Hane Naoki and Motoki Katsuya) showed this other variation. This seems a bit passive. I'd be happy with White.

Click Here To Show Diagram Code

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

From what I read, the player's did not discuss this move themselves. They focused instead on the cut in the bottom right and the bigger fight that followed. The game got wild and difficult for me to follow so it was nice to have the net commentary.

I'm looking forward to the next game in this title match.

18 and 20 are not new, just infrequent. The inverse order is relatively more frequent, IMX.

Well, I only found one game with the pincer (W18) and the keima (W20) in that order. I did see a different order in several games, as mentioned. Surely the pincer and keima have been played more than what I've seen but Ichiriki's rare order of moves seemed to be what induced the novel result in that quadrant. I found that interesting because the commentator's had different ideas that were more what I would expect to see. I wonder what result Ichiriki was hoping for.

Your assumption was essentially correct, and is not overridden by Mutsuura's comment. A kufuu is a mostly move that you have dredged up from your memory and want to try it out. Either because you think it might work well now, or because you want to try a bit of psy-ops. In other words, it has been played before. The GoGoD database has over 20 examples (from 1941, but mostly fashionable from about 2010), but with the exception of Yoda, no player has tried it twice. Precisely because it's seen as a special tool you use only in special circumstances. Or, if you like, it's a "I think I'll give this a whirl" kind of move. (Apart from that, one Japanese word that is associated with kufuu is omoimegarasu.)

It is possible, of course, to use the phrase shin-kufuu, which would indeed be a new idea, or invention. However, even there, the word associations are very much of the "let's give it a whirl" variety, and rather than 'new idea' a better English translation would typically be 'an expedient', or 'resourcefulness.'

I'm not familiar with "omoimegarasu" and my dictionary is not too helpful but is it similar to omoi mawasu (ruminating)?

As I said I found this position with a different move order several times but I have still only seen the one game with Yoda where Fujita played the same sequence (2018-05-03). By the way, that game ended up similar to the variation shown in the post game newspaper commentary (above).

Maybe I took "kufuu" as being too innovative but I have seen even rarer opening positions (below) merely called "joban sakusen." At the very least the move order in the Kisei game led to an interesting corner fight. Looking into this more it seems like this pincer and keima combination is an AI teaching. So maybe Ichiriki had seen it and decided to give it a whirl.

Click Here To Show Diagram Code

[go]$$Wc White's joban sakusen
$$ ---------------------------------------
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . O . . . . . 3 . . . . O . . . . |
$$ | . . . , O . . . . , . . . 5 . , X . . |
$$ | . . X . . . . . . . . . . . . 4 . . . |
$$ | . . . 1 . . . . . . . . . . 7 . . . . |
$$ | . . 2 . . . . . . . . . . . . 8 . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . , . . . . . , . . . . . , . . . |
$$ | . . . . . . . . . . . . . . . . 6 . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ ---------------------------------------[/go]

By the way, I found a variation of this position starting from the 6-4 point (double 6-4 fuseki in fact).

Click Here To Show Diagram Code

[go]$$ Move sequence looking only at this corner
$$ ---------------------------------------
$$ | . . . . . . . . . . .|
$$ | . . . . . . . . . . .|
$$ | . . 4 3 6 . . . . . .|
$$ | . . 9 7 8 1 . . . , .|
$$ | . . . 2 . 0 . . . . .|
$$ | . . . . . . . . . . .|
$$ | . . 5 . . . . . . . .|
$$ | . . . . . . . . . . .|
$$ | . . . . . . . . . . .|
$$ | . . . , . . . . . , .|
$$ | . . . . . . . . . . .|
$$ ---------------------------------------[/go]

Another interesting move out of the 46th Kisei title match.

Click Here To Show Diagram Code

[go]$$c
$$ ---------------------------------------
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . O O . O . . . . . . . . . . . . |
$$ | . . . , X X . . . , . . . . . X . . . |
$$ | . . X . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . , . . . . . , . . . . . , 2 . . |
$$ | . . . . . . . . . . . . . . . b . . . |
$$ | . . . . . . . . . . . . . . . 1 a 6 . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . 4 O . . |
$$ | . . O , . . . . . , . . . 5 . , 3 . . |
$$ | . . . . . . . . . . . . . . . X . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ ---------------------------------------[/go]

The Yugen no Ma commentator mentioned that he had never seen . Looking at published records I only saw one other game with this local position between Segawa Yoshio and Shumamura Toshihiro in 1954. Point a, mentioned by the Yomiuri commentary was common. According to them, is quicker in that it settles the position with this one move while A (common ) and B (I couldn't find it) require an additional move.

The Yomiuri commentary also said something that I'm not sure what to make of: 白１は「懐かしい手」と検討陣。 (白１ is )
There are only a handful of pages notes in my previously owned 2000 page Japanese dictionary and 懐かしい is one of the marked words. It means nostalgic, beloved, dear, or maybe wistful. A nostalgic move? This doesn't seem to be a Go term. I searched and only discovered nostalgia for hand (手) rolled sushi.

Anyway, I don't see that two spacer high pincer much myself so I'll file this away for later.

「懐かしい手」と検討陣

A "blast from the past" remarked he analysis team.

Or "an old(-fashioned) move" or "a move from the good old days" etc, etc.

It goes back a long way but was especially a staple in the early 50s, i.e. the time of the likes of Sakata and Takagawa. The days when people played go only on real boards and a computer was a guy who counted the cards in blackjack.

A blast from the past. It seemed like they mentioned that on-stream too but I didn't catch much of what they said. I thought it was about the 2-space high pincer and the 3-10 point played in response. Though maybe this play underneath was popular but just not played in published games. Thanks for the tip.