Regarding the scalar curvature equation or the Brezis-Nirenberg problem, the classical existence results involve either local terms (in large dimension) or global terms (in low-dimension). Conversely, the Pohozaev obstructions yield nonexistence results. Druet-Laurain proved that these obstructions are stable in low-dimension.
In this talk, we will discuss the same issue for Hardy-Sobolev equations. It turns out that when the singularity is in the domain, then a similar low-dimensional phenomenon occurs. When the singularity is on the boundary of the domain, we show that there is a universal stability independent of the dimension.
This is joint work with Nassif Ghoussoub (UBC) and Saikat Mazumdar (Bombay).