An important issue towards a broader acceptance of answer-set programming
(ASP) is the deployment of tools which support the programmer during the coding
phase. In particular, methods for debugging an answer-set program are
recognised as a crucial step in this regard. Initial work on debugging in ASP
mainly focused on propositional programs, yet practical debuggers need to
handle programs with variables as well. In this paper, we discuss a debugging
technique that is directly geared towards non-ground programs.