  In this paper we present InterHorn, a solver for recursion-free Horn clauses.
The main application domain of InterHorn lies in solving interpolation problems
arising in software verification. We show how a range of interpolation
problems, including path, transition, nested, state/transition and well-founded
interpolation can be handled directly by InterHorn. By detailing these
interpolation problems and their Horn clause representations, we hope to
encourage the emergence of a common back-end interpolation interface useful for
diverse verification tools.
