## Olaf Steinbach (TU Graz)

Combined boundary integral equations are used when the classical
boundary integral formulation is not unique solvable while the
underlying boundary value problem has a unique solution. Well
known examples are the Brakhage-Werner or Burton-Miller formulations
for exterior Helmholtz problems, or the combined boundary field
integral equation approach for the Maxwell system.
The unique solvability of combined boundary integral equations
strongly relies on the used functional setting. When considering
combined boundary integral equations in the natural energy spaces
certain regularisations are needed.

In this talk we will describe several regularized combined boundary
integral equations for exterior Helmholtz problems and we will
discuss possible extensions for the Maxwell system.