I got asked what to think about an early pincer:

I let ELF answer (Have a look at the different winrates for black):

I think its because those strong bots don't value influence very much (as they probably know how to deal with it very well). Hence the high win probabilities for the early 3-3.

Hi Gomoto,

Thanks. That early pincer never felt right to me,
but of course I had no way to objectively prove it.

Thanks to DM, and these bots.

When I was in BIBA in 2013 On Sojin 7p said he didn't think pincer was good in parallel 4-4s, just back off better. Reason is the take corner joseki is locally good for black (even more obvious now if you compare it to 3-3 invasions now considered even) so pincer should only be played if pincer direction is particularly important. So if lower right is a 3-4 towards right edge then approach there is a good move for white to spend the sente afterwards which makes pincer plausible, and pincer also disrupts mini-Chinese type openings (psychological value too). I suppose Elf thinks that pincer is bad too, but not so much.

Interesting to note that after the pincer, a human would invade the lower left corner while the bot would invade the upper left corner.

Checking AlphaGo Teach (probably stronger than Elf, but sometimes I have doubts) for the Sojin argument:

With parallel 4-4s, pincer is 46.9% for black, back off is 44.9% (and best).

Click Here To Show Diagram Code

[go]$$B
$$ +---------------------------------------+
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$$ | . . . O . . . . . , . . . . . X . . . |
$$ | . . . . . 5 . b . . . . . . . . . . . |
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$$ | . . . . . . . . . . . . . . . . . . . |
$$ +---------------------------------------+[/go]

If pincer then 3-3 invade top left is best (46.6%, != 46.9 so we can see these values have a few tenths of a percent variation). Lower left 3-3 is 43.7, i.e. more of a mistake that white's pincer. With the normal human joseki, AGT says black ends with 46.5 at the end (if top right 3-3), more normal human o3 approach is similar at 46.7. So AG agrees that this end result is better for black than if white just backed off initially, and basically the same as after the pincer. Agrees with Sojin/me.

Click Here To Show Diagram Code

[go]$$Bcm7 Human joseki ends black 46.5
$$ +---------------------------------------+
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$$ | . . 9 . . . . . . . . . . . . . . . . |
$$ | . . . 4 . . . . . . . . . . . . . . . |
$$ | . . 3 O . . . . . , . . . . . X . . . |
$$ | . . 1 2 8 X . O . . . . . . . . . . . |
$$ | . . 7 5 6 . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ +---------------------------------------+[/go]

However, both players have made significant mistakes! As discussed on the boards before, white 14 should have not been solid connect but underneath for a 5% better result. So if white does this black loses a lot more than the small gain he got from white's bad pincer. This move wasn't unknown to humans before and has been played a few times, but was a fairly obscure move. My wife remembers being told off by her teachers when she wanted to play here. Also instead of 11 hane AGT says black should have played b6 knight move (2% difference), I suppose this doesn't damage f3 so much. Disagrees with Sojin/me.

Click Here To Show Diagram Code

[go]$$Bcm7 White better answer, black 40.6
$$ +---------------------------------------+
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$$ | . . 9 . . . . . . . . . . . . . . . . |
$$ | . . . 4 . . . . . . . . . . . . . . . |
$$ | . . 3 O . . . . . , . . . . . X . . . |
$$ | . . 1 2 . X . O . . . . . . . . . . . |
$$ | . . 7 5 6 8 . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ +---------------------------------------+[/go]

How about the lower right being a 3-4 point?
TBC

P.S. I don't think this belongs in Beginners forum!