||Together with with J.-R. Kweon, I have been
been studying the interior regularity or irregularity of the equations of viscous compressible flow in a plane polygonal region.
I shall discuss 3 problems whose resolution would advance these investigations. The first problem involves the resolvant of a non-self-adjoint operator. The second problem deals with a linear first order PDE. The third problem is only partly mathematical; the non-mathematical part concerns some physics and, perhaps, experiments.