A semantic framework for preference handling in answer set programming
  We provide a semantic framework for preference handling in answer set
programming. To this end, we introduce preference preserving consequence
operators. The resulting fixpoint characterizations provide us with a uniform
semantic framework for characterizing preference handling in existing
approaches. Although our approach is extensible to other semantics by means of
an alternating fixpoint theory, we focus here on the elaboration of preferences
under answer set semantics. Alternatively, we show how these approaches can be
characterized by the concept of order preservation. These uniform semantic
characterizations provide us with new insights about interrelationships and
moreover about ways of implementation.
