Safe first-order formulas generalize the concept of a safe rule, which plays an important role in the design of answer set solvers. We show that any safe sentence is equivalent, in a certain sense, to the result of its grounding---to the variable-free sentence obtained from it by replacing all quantifiers with multiple conjunctions and disjunctions. It follows that a safe sentence and the result of its grounding have the same stable models, and that stable models of a safe sentence can be characterized by a formla of a simple syntactic form.

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In International Conference on Logic Programming (ICLP) 2008.

@InProceedings{lee:iclp2008, title={Safe Formulas in the General Theory of Stable Models (preliminary report)}, author={Joohyung Lee and Vladimir Lifschitz and Ravi Palla}, booktitle={International Conference on Logic Programming (ICLP)}, url="http://www.cs.utexas.edu/users/ai-lab?lee:iclp2008", year={2008} }