A month or so ago, though, a new-ranks 4d player advised me that Black should take the R13 atari immediately, a recommendation I just remembered whilst reviewing a sanrensei game.
What do you think of this? I can see that it removes a white point in sente, makes a potential point for Black, and removes the possibility of S14 being a white eye, a fact that might be relevant in certain obscure ko situations. And it won’t be sente after Black fixes the cut with O13.
Also, regardless of whether Black makes that atari, it should be noted on the position that Black very often does play the O13 fix. In fact, it’s questionable whether the position can really be called settled with the P13 cut still on the board.
It’s not sente really though, white can, and probably would tenuki.
If Black captures, White recaptures, but it doesn’t change the fact White is alive [S16 and T15]. Black might gain one point, but white probably gets more with sente.
I think there’s a strong potential to just sacrifice one or both of the two stones at Q13 and R12, to get moves on the side for instance.
I could look up some pro games where this happens.
I guess if Black does capture the two stones, it removes some aji for an invasion in the topside in the OJE.
If it isn’t the first corner joseki played I can kind of understand why you’d answer the atari. I’m not sure I believe one has to answer that atari though immediately if there’s bigger points on the board.
Edit: On waltheri (from a quick filter), you are right that not ignore the atari isn’t very common but here’s at least two games.
Here’s what I learned about this joseki from my teachers:
Black has two cutting points, marked with triangles.
Black must protect one of them to finish the joseki. If black chooses to protect the upper cutting point as shown in the diagram, there remains an invasion point at A which threatens to connect up with the white corner. The exact method is left as an exercise to the reader - you should try it yourself and enjoy the variations.
That said, I ran 100k playouts with Leela. It seems to regard the connection as somewhat slow, preferring to play in a different corner instead:
In this position, white gets the upper side.
Alternatively, it could end up like in Cho Chikun’s game above, where white munches four stones and black retains the outside.
Let’s talk about the atari on the two stones.
I believe it is a classic example of an unnecessary exchange.
White will connect the stones and black will simply come back to protect the cutting point.
In some far-fetched scenarios, this could cost black a liberty and a ko threat.
According to the 1-2-3 principle, black should just protect.
I think this has been a pretty good discussion so far, and I’ve been fairly interested in this joseki, I kind of like playing sanrensei.
I haven’t seen this joseki in any recent video series that I remember, but one could try searching for sanrensei in various languages and see what comes up.
1 was played 1997–2017 2 was played 1997–2005 3 was played 2002-2018
So a surface analysis suggests that 3 is the most recent development of the sanrensei.
And whereas you might well want to play 2 and then 1, you don’t want to play 2 and then 3. It’s also not advisable to play 2 on its own, without following it with 1.
Observe also that White’s preference for this variation doesn’t seem to appear until the late '90s, in what I call the Late Modern Period (1990–2014). In the heyday of the sanrensei, say the '30s to '80s, it doesn’t appear to have been part of the theory of that opening system.
Here are all the atari sanrensei games I could find in Waltheri.
You can see that it was something that was briefly popular from 1997 to 1999. Note also that only Yamashiro Hiroshi liked it enough to try it twice. One more piece of data is that, barring Zhang–Yang, it was a Japanese and Korean trend.
Commentary by Takamiya Masaki.
