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Journals and Conferences
In this paper we propose an efficient algorithmic solution to the problem of determining a Bisimulation Relation on a finite structure. Starting from a set-theoretic point of view we propose an algorithm that optimizes the solution to the Relational coarsest Partition problem given by Paige and Tarjan in 1987 and its use in model-checking packages is… (More)
An extended logic programming language is presented, that embodies the fundamental form of set designation based on the (nesting) element insertion operator. The kind of sets to be handled is characterized both by adaptation of a suitable Herbrand universe and via axioms. Predicates 2 and = designating set membership and equality are included in the base… (More)
We propose an efficient algorithmic solution to the problem of determining a Bisimulation Relation on a finite structure working both on the explicit and on the implicit (symbolic) representation. As far as the explicit case is concerned, starting from a set-theoretic point of view we propose an algorithm that optimizes the solution to the Relational… (More)
We study the complexity of the Subgraph Bisimulation Problem, which stands to Graph Bisimulation as Subgraph Isomorphism stands to Graph Isomorphism and we prove its NP-Completeness. Our analysis is motivated by its applications to Semistructured Databases.
In this paper we consider the relative expressive power of two very common operators applicable to sets and multisets: the with and the union operators. For such operators we prove that they are not mutually expressible by means of existentially quantified formulae. In order to prove our results, canonical forms for set-theoretic and multiset-theoretic… (More)
In this paper we present a novel methodology to compute stable models in Answer Set Programming. The process is performed with a bottom-up approach that does not require the preprocessing of the typical grounding phase. The implementation is completely in Prolog and Constraint Logic Programming over finite domains.
Reduced representations of proteins have been playing a keyrole in the study of protein folding. Many such models are available, with different representation detail. Although the usefulness of many such models for structural bioinformatics applications has been demonstrated in recent years, there are few intermediate resolution models endowed with an… (More)
The protein structure prediction problem is one of the most challenging problems in biological sciences. Many approaches have been proposed using database information and/or simplified protein models. The protein structure prediction problem can be cast in the form of an optimization problem. Notwithstanding its importance, the problem has very seldom been… (More)
In this paper we present a study of the problem of handling constraints made by conjunctions of positive and negative literals based on the predicate symbols =, <inline-equation> <f> ∈,<hsp sp="0.265">∪</f> </inline-equation> and <inline-equation> <f> &dvbm0;</f> </inline-equation> (i.e., disjointness of two sets) in a (hybrid) universe of <?Pub… (More)
An extended logic programming language embodying sets is developed in successive stages, introducing at each stage simple set dictions and operations, and discussing their operational as well as declarative semantics. First, by means of special set terms added to definite Horn Clause logic, one is enabled to define enumerated sets. A new unification… (More)