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- Raffaella Gentilini, Carla Piazza, Alberto Policriti
- J. Autom. Reasoning
- 2003

The notions of bisimulation and simulation are used for graph reduction and are widely employed in many areas: modal logic, concurrency theory, set theory, formal verification, and so forth. In particular, in the context of formal verification they are used to tackle the so-called state-explosion problem. The faster algorithms to compute the maximum… (More)

- Agostino Dovier, Carla Piazza
- IEEE Trans. Knowl. Data Eng.
- 2003

We study the complexity of the Subgraph Bisimulation Problem, which stands to Graph Bisim-ulation as Subgraph Isomorphism stands to Graph Isomorphism and we prove its NP-Completeness. Our analysis is motivated by its applications to Semistructured Databases.

- Agostino Dovier, Carla Piazza, Alberto Policriti
- FroCoS
- 1999

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 quantiied formulae. In order to prove our results, canonical forms for set-theoretic and multiset-theoretic… (More)

- Raffaella Gentilini, Carla Piazza, Alberto Policriti
- SODA
- 2003

We present an algorithm that computes in a linear number of symbolic steps (<i>O</i>(|<i>V</i>|)) the strongly connected components (sccs) of a graph <i>G</i> = ⟨<i>V, E</i>⟩ represented by an Ordered Binary Decision Diagram (OBDD). This result matches the complexity of the (celebrated) Tarjan's algorithm operating on explicit data… (More)

- Agostino Dovier, Carla Piazza, Enrico Pontelli, Gianfranco Rossi
- ACM Trans. Program. Lang. Syst.
- 2000

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)

- Agostino Dovier, Carla Piazza, Alberto Policriti
- CAV
- 2001

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)

- Annalisa Bossi, Carla Piazza, Sabina Rossi
- Proceedings. 17th IEEE Computer Security…
- 2004

Information flow security properties such as noninterference ensure the protection of confidential data by strongly limiting the flow of sensitive information. However, to deal with real applications, it is often necessary to admit mechanisms for downgrading or declassifying information. In this paper, we propose a general unwinding framework for… (More)

- Annalisa Bossi, Riccardo Focardi, Carla Piazza, Sabina Rossi
- LOPSTR
- 2002

- Carla Piazza, Alberto Policriti
- TPLP
- 2004

We propose an alternative way to represent graphs via OBDDs based on the observation that a partition of the graph nodes allows sharing among the employed OBDDs. In the second part of the paper we present a method to compute at the same time the quotient w.r.t. the maximum bisimulation and the OBDD representation of a given graph. The proposed computation… (More)

- Agostino Dovier, Carla Piazza, Alberto Policriti
- Theor. Comput. Sci.
- 2004

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)