Gokyo Shumyo, Section 1, Problem 75 / Varation

Variation at 2  

I believe that the / exchange is unnecessary, and that at already forces . Otherwise at seems to live or get out very quickly. So here, IMHO, is the main line.

Main line  

White 11 at a makes an eye.

Variation at 6 (ii)  

@

Continuation  

If Black a, b, or c, White d.