Continuing his epic voyage to explain why various old fuseki patterns have disappeared in the AI age, Meijin Shibano Toramaru has turned his attention to the dangerously endangered species - the pincer. I think Bill was the first to alert us to this side effect of digital warming, but I don't think he - or Shibano or anyone else - has satisfactorily explained why pincers have gone to the brink of extinction.

Oddly enough, I think I may have discovered the reason, though quite accidentally. I will leave the details to another post, but (if I'm right) it's connected with another AI feature that Bill is currently forcing us to re-examine - the press. My own clue, however, was the concept of the barmkin.

Shibano, at least for the time being, dodges the reason for pincer endangerment and focuses instead on the survival of one particular pincer.



Shibano notes that for a long time the teiban (定番) joseki against the high approach was A. A teiban (short for 定番商品) is a plain standard product that sells consistently well. We might call it the plain vanilla cornet that mature adults prefer. Kiddies may be tempted by extra hundreds and thousands and monkey's blood, and (judging by adverts I've seen on tv under enforced lockdown) ice-cream vendors may try to seduce the grown-ups with flavours such as ruby cocoa beans - I think they mean chocolate but organolepsis may prove otherwise - but plain vanilla never fails the true aficionado.

But the go board is a cruel place, and it seems that tastes have changed. Plain vanilla still exists but comes in fancy new packaging - a safe tub instead of a wobbly, melting cornet!

The new variety here is the low two-space pincer.

This pincer itself is not new - in fact this year is the 200th anniversary of its appearance. It has, however, been especially popular in recent years, though it cannot claim to be a child of the AI revolution. It is rather a child of the naughty noughties. A millennial. What is special about it is that it has apparently survived the AI onslaught.

AI killed off the Magic Sword, which had previously been assessed by humans as good for the sword holder (Black here. The reason was that Black typically got magnificent thickness in return for White profit in the corner. But in gote. It is now well known that AI has shown that thickness may appear as terrifying as a chimera but it is often just as much a phantasm. In the case of the Magic Sword, according to Shibano, AI rates sente as more than enough compensation for the awe-invoking chimera.

The low pincer apparently does not suffer from this defect. Shibano only gives a hint as to why, but one aspect appears to be that the low stone is easy to sacrifice - to treat lightly - and as a result Black is the one that can usually get sente. He does not then get an advantage - just parity. But that's enough to keep it in the armoury, especially for formations such as the one on the right, which is the one Shibano shows.

It appears that White's favoured response now is the odd-looking move at B (which I think I now understand as a result of my accidental discovery). I only have nine examples of that in the GoGoD database, It is an AlphaGo innovation, but FineArt has also played it. In fact, the three AI examples are all against other bots. But Shibano gives a couple of examples that don't appear in the database, so it would seem that most activity in this area is in trial internet games.

I hope Shibano will come back to this topic next week, but in the interim it would be interesting to hear opinions as to why this low pincer may have found a way to survive against the odds.

As I wrote a decade ago, the pincer is possible with strong support ftom the LR corner, the players must avoid some traps, and White's next move can be a tenuki or some jump outwards fitting the global context.

Shibano has announced he is ending his Fuseki Revolution series after 74 episodes, having planned to end it several times before, only to be dissuaded by the clamour from fans for more.

He signed off with this position:



The high central pincer is one of the few that AI seems happy to include in its "Arsenal of Immortals' Devices" and the usual responses by White have been A, B, C and D. But F has become popular recently. I had not noticed that, no doubt because - as Shibano notes - it is not a new move. But it turns out I already have a dozen or so examples for this truncated year, and the move had already been gaining traction in late 2019.

What makes this move stand out is that White is trying to settle himself. If Black goes along with that (e.g. exchanging C for F), his pincer stone ends up as neither fish nor fowl. Or to put it another, this creates a Go Seigen group for White and so the entire SW quadrant is likely to end up as no man's land, which is not good for Black as he will have played an extra stone there.

Black has therefore been tempted to keep White unsettled by checking at F, or even attaching one point to the right. Playing thereafter in the ordinary way seems unsatisfactory for White, but White has apparently come up with a strong continuation (against F) at the 5-5 point.

One puzzle, though, not mentioned by Shibano, is that the White slide is being used by a wave of AI-influenced human pros but, in this position at least, it doesn't seem even to show up on Lizzie's radar.