Set Constraints on Regular Terms
نویسندگان
چکیده
Set constraints are a useful formalism for verifying properties of programs. Usually, they are interpreted over the universe of finite terms. However, some logic languages allow infinite regular terms, so it seems natural to consider set constraints over this domain. In the paper we show that the satisfiability problem of set constraints over regular terms is undecidable. We also show that, if each function symbol has the arity at most 1, then this problem is EXPSPACE-complete.
منابع مشابه
Sorted Unification Using Set Constraints
This paper describes a new representation for sortal constraints and a uniication algorithm for the corresponding constrained terms. Variables range over sets of terms described by systems of set constraints that can express limited inter-variable dependencies. These sets of terms are more general than regular tree languages, but are still closed under intersection. The new uniication algorithm...
متن کاملDeciding Regularity of the Set of Instances of a Set of Terms with Regular Constraints is EXPTIME-Complete
Finite-state tree automata are a well studied formalism for representing term languages. This paper studies the problem of determining the regularity of the set of instances of a finite set of terms with variables, where each variable is restricted to instantiations of a regular set given by a tree automaton. The problem was recently proved decidable, but with an unknown complexity. Here, the e...
متن کاملCLP(H): Constraint logic programming for hedges
CLP(H) is an instantiation of the general constraint logic programming scheme with the constraint domain of hedges. Hedges are finite sequences of unranked terms, built over variadic function symbols and three kinds of variables: for terms, for hedges, and for function symbols. Constraints involve equations between unranked terms and atoms for regular hedge language membership. We study algebra...
متن کاملRegular expression order-sorted unification and matching
We extend order-sorted unification by permitting regular expression sorts for variables and in the domains of function symbols. The obtained signature corresponds to a finite bottom-up unranked tree automaton. We prove that regular expression order-sorted (REOS) unification is of type infinitary and decidable. The unification problem presented by us generalizes some known problems, such as, e.g...
متن کاملRational Spaces and Set Constraints
Set constraints are inclusions between expressions denoting sets of ground terms They have been used extensively in program analysis and type inference In this paper we investigate the topological structure of the spaces of solutions to systems of set constraints We identify a family of topological spaces called rational spaces which formalize the notion of a topological space with a regular or...
متن کامل