Suppose White has the corner sealed off, as in this diagram. Clearly, Black can't live invading at the 3-3 point. The points a and b are miai after the moves to .
Even if the white stones are set as far away as the seventh or eighth line, I found it impossible to create a living group. At ten lines, I lived and at nine I didn't, but of course here my limited skill became a factor.
What does the SL visitor think about this ? What is the cutting edge for White's stones to be away from the corner, before Black can live ?
I seem to remember this being something professionals had investigated, with the agreement being Black cannot live even with white stones on the tenth line. Or maybe tenth line made it ko or seki? I think we should investigate. :)
Was this based on assuming an invasion at sansan only? I would imagine that at a 10x10 enclosure, starting at the 3-4 point makes miai out of an enclosure or an extension to the 3-7 point and it might be possible to scrape out a measly living ... ?