A finite logical disjunction of atomic first-order formulas or their negations, normally understood to have all its free variables universally quantified. An empty logical disjunction is false. A Horn clause has at most one positive atom.
A first-order clause containing no variables. Its first-order terms are ground terms, so resolution between such first-order clauses reduces to propositional logic on the ground atoms.
A representation by a set of first-order clauses, interpreted as their logical conjunction. General first-order formulas can be transformed by Skolemization and conversion to conjunctive normal form, preserving satisfiability in an expanded first-order signature.
In an expanded signature, Skolemization preserves equisatisfiability rather than equivalence under arbitrary interpretations of the new function symbols.
Articles by others on the same topic
There are currently no matching articles.