Edit:
More specifically I am considering this position after this follow up sequence (not good for black). I made an overgeneralization with the proposed starter position of this thread probably.
I don't always big wedge, but when I do, I'd hit the 3rd line (for this board), like (b). And yes, there are cases that called for a 5th line or higher wedge.
What does the engine say about (c) instead ?
Does the engine rate this OK for ?
I will add some variations later. But here are some examples I am thinking about.
The exchange (not good for black) black N3, white O3, black O4 makes R11 the especially interesting invasion point. (I also had some boards with the exact start position of this thread, but I cant recreate them for now, perhaps it is an over generalization by me and I have to change the start position accordingly later.)
invhot1.jpg (168.27 KiB) Viewed 9985 times
invhot2.jpg (170.86 KiB) Viewed 9985 times
Re: Looking for the invasion hotspot
Posted: Tue Sep 25, 2018 9:48 pm
by Gomoto
@EdLee:
what about the symmetrical (on the right) position?
invhot3.jpg (171.52 KiB) Viewed 9985 times
Re: Looking for the invasion hotspot
Posted: Wed Sep 26, 2018 12:46 am
by John Fairbairn
If you allow for minor joseki variation in the bottom three lines of your diagram, Chinese pros have faced this position and played your R11 five times (all in 2017). Twice they played, for Black, from above and twice from below, and once ignored the move.
But my main reason for posting is to ask why you call it an invasion. It would normally be called a wariuchi. An invasion implies things like specific and obvious weak points (often just one) or the last move before a moyo is completed. It leads to tactics. A wariuchi is about strategy - it is about dividing the board up into competing spheres of influence. Using each term correctly gives us access to a range of advice, in the form of proverbs and other shared past experiences.
But, as I mentioned in a separate thread (with nil response), AI appears to have given us reasons to re-think our definitions of (and so the meanings behind) extensions. Others, Bill especially, have remarked on the very different way AI treats pincer opportunities (perhaps, if AlphaGo could learn to talk by itself, it wouldn't even invent a term for pincer?). And perhaps the first thing we all gleaned from AI was that what was traditionally considered thickness (the Black shape emerging from the continuations in the lower right) was not thickness at all.
It seems reasonable, therefore, to posit that AI may be guiding us towards re-appraising what an invasion and a wariuchi is. The split Black response in the five games I mentioned here may be a sign that pros are still not quite sure whether the Black shape(s) in the lower right are fish or fowl and that in turn affects how they view the possibilities on the right side.
So what is your view of what is going on on the right side? I suppose one obvious question is that although Elf is highlighting R11 in this area, is it actually also highlighting this area for the very next move, or is it favouring tenuki, as in one of the five games above (there the tenuki was a 3-3 invasion)?
Re: Looking for the invasion hotspot
Posted: Wed Sep 26, 2018 4:37 am
by Elom
In my interpretation of the double wall diagram, white is perfectly placed near black's thickness. I think black would like to extend up to R10 from each group, but any of the four moves from Q10 to R11 prevent that.
The same seems true in the diagram where white plays R11 with black having a star-point stone in the upper right, but here white also seems to be perfectly placed to approach or attach in the upper right. Attaching and creating a crosscut seems better because if white approaches, black can kick and then cramp white in a similar way white did to black.
Re: Looking for the invasion hotspot
Posted: Wed Sep 26, 2018 5:36 am
by Gomoto
Thanks John for pointing out the games by Chinese pros, I will have a look at them.
I understand that the term wariuchi (perhaps: dividing move?) is more appropriate than the term invasion for this move.
(But on the otherhand I think it is quite funny, that I try to think about the move more as an invasion than a dividing move. My goal is to not play just a move to divide, but to aim for the perceived "weaknesses" in the black position and ground my decision on the specific follow up variations.)
Posted: Wed Sep 26, 2018 5:40 am
by EdLee
Hi Gomoto,
I don't know who came up with the term big wedge, but I like and use it.
Re: Looking for the invasion hotspot
Posted: Wed Sep 26, 2018 5:51 am
by Gomoto
some variations
Re: Looking for the invasion hotspot
Posted: Wed Sep 26, 2018 5:55 am
by Gomoto
3-3 is definitly a possible too. But I have a special interest in the option to play the big wedge on the right side and the possible follow up variations, just because I am curious. Especially I am interested in the tactical relations that causes the AI to prefer R11 over Q10.
(I am also interested in which positions the AI thinks the attachment to 4-4 is an option to the 3-3 invasion.)
And yes, there are cases that called for a 5th line or higher wedge.
(c) instead ?