  This paper focuses on the expressive power of disjunctive and normal logic
programs under the stable model semantics over finite, infinite, or arbitrary
structures. A translation from disjunctive logic programs into normal logic
programs is proposed and then proved to be sound over infinite structures. The
equivalence of expressive power of two kinds of logic programs over arbitrary
structures is shown to coincide with that over finite structures, and coincide
with whether or not NP is closed under complement. Over finite structures, the
intranslatability from disjunctive logic programs to normal logic programs is
also proved if arities of auxiliary predicates and functions are bounded in a
certain way.
