
Antonio Bucciarelli, Adolfo Piperno, and Ivano Salvo. "Intersection types and λdefinability." Mathematical Structures in Computer Science 13, no. 1 (2003): 15–53. Cambridge University Press. ISSN: 09601295. DOI: 10.1017/S0960129502003833.
Abstract: This paper presents a novel method for comparing computational properties of λterms that are typeable with intersection types, with respect to terms that are typeable with Curry types. We introduce a translation from intersection typing derivations to Curry typeable terms that is preserved by βreduction: this allows the simulation of a computation starting from a term typeable in the intersection discipline by means of a computation starting from a simply typeable term. Our approach proves strong normalisation for the intersection system naturally by means of purely syntactical techniques. The paper extends the results presented in Bucciarelli et al. (1999) to the whole intersection type system of Barendregt, Coppo and Dezani, thus providing a complete proof of the conjecture, proposed in Leivant (1990), that all functions uniformly definable using intersection types are already definable using Curry types.



Antonio Bucciarelli, and Ivano Salvo. "Totality, Definability and Boolean Circuits." 1443 (1998): 808–819. Springer. DOI: 10.1007/BFb0055104.
Abstract: In the type frame originating from the flat domain of boolean values, we single out elements which are hereditarily total. We show that these elements can be defined, up to total equivalence, by sequential programs. The elements of an equivalence class of the totality equivalence relation (totality class) can be seen as different algorithms for computing a given settheoretic boolean function. We show that the bottom element of a totality class, which is sequential, corresponds to the most eager algorithm, and the top to the laziest one. Finally we suggest a link between size of totality classes and a well known measure of complexity of boolean functions, namely their sensitivity.



Antonio Bucciarelli, Silvia de Lorenzis, Adolfo Piperno, and Ivano Salvo. "Some Computational Properties of Intersection Types (Extended Abstract)." (1999): 109–118. IEEE Computer Society. DOI: 10.1109/LICS.1999.782598.
Abstract: This paper presents a new method for comparing computationproperties of λterms typeable with intersection types with respect to terms typeable with Curry types. In particular, strong normalization and λdefinability are investigated. A translation is introduced from intersection typing derivations to Curry typeable terms; the main feature of the proposed technique is that the translation is preserved by βreduction. This allows to simulate a computation starting from a term typeable in the intersection discipline by means of a computation starting from a simply typeable term. Our approach naturally leads to prove strong normalization in the intersection system by means of purely syntactical techniques. In addition, the presented method enables us to give a proof of a conjecture proposed by Leivant in 1990, namely that all functions uniformly definable using intersection types are already definable using Curry types.
Keywords: lambda calculusCurry types, intersection types, lambdadefinability, lambdaterms, strong normalization



V. Bono, and I. Salvo. "A CuCh Interpretation of an ObjectOriented Language." Electronic Notes in Theoretical Computer Science 50, no. 2 (2001): 159–177. Elsevier. Notes: BOTH 2001, Bohmâ€™s theorem: applications to Computer Science Theory (Satellite Workshop of ICALP 2001). DOI: 10.1016/S15710661(04)001719.
Abstract: CuCh machine extends pure lambdaÃâcalculus with algebraic data types and provides a the possibility of defining functions over the disjoint sum of algebras. We exploit such natural form of overloading to define a functional interpretation of a simple, but significant fragment of a typical objectoriented language.



Franco Barbanera, Mariangiola DezaniCiancaglini, Ivano Salvo, and Vladimiro Sassone. "A Type Inference Algorithm for Secure Ambients." Electronic Notes in Theoretical Computer Science 62 (2002): 83–101. Elsevier. Notes: TOSCA 2001, Theory of Concurrency, Higher Order Languages and Types. DOI: 10.1016/S15710661(04)003214.
Abstract: We consider a type discipline for the Ambient Calculus that associates ambients with security levels and constrains them to be traversed by or opened in ambients of higher security clearance only. We present a bottomup algorithm that, given an untyped process P, computes a minimal set of constraints on security levels such that all actions during runs of P are performed without violating the security level priorities. Such an algorithm appears to be a prerequisite to use type systems to ensure security properties in the web scenario.



Mario Coppo, Mariangiola DezaniCiancaglini, Elio Giovannetti, and Ivano Salvo. "Mobility Types for Mobile Processes in Mobile Ambients." Electr. Notes Theor. Comput. Sci. 78 (2003). DOI: 10.1016/S15710661(04)810119.
Abstract: We present an ambientlike calculus in which the open capability is dropped, and a new form of Ã¢â¬ÅlightweightÃ¢â¬Â process mobility is introduced. The calculus comes equipped with a type system that allows the kind of values exchanged in communications and the access and mobility properties of processes to be controlled. A type inference procedure determines the Ã¢â¬ÅminimalÃ¢â¬Â requirements to accept a system or a component as well typed. This gives a kind of principal typing. As an expressiveness test, we show that some well known calculi of concurrency and mobility can be encoded in our calculus in a natural way.



Giuseppe Della Penna, Benedetto Intrigila, Igor Melatti, Enrico Tronci, and Marisa Venturini Zilli. "Finite horizon analysis of Markov Chains with the Mur$\varphi$ verifier." Int. J. Softw. Tools Technol. Transf. 8, no. 4 (2006): 397–409. SpringerVerlag. ISSN: 14332779. DOI: 10.1007/s1000900502167.
Abstract: In this paper we present an explicit diskbased verification algorithm for Probabilistic Systems defining discrete time/finite state Markov Chains. Given a Markov Chain and an integer k (horizon), our algorithm checks whether the probability of reaching an error state in at most k steps is below a given threshold. We present an implementation of our algorithm within a suitable extension of the Mur$\varphi$ verifier. We call the resulting probabilistic model checker FHPMur$\varphi$ (Finite Horizon Probabilistic Mur$\varphi$). We present experimental results comparing FHPMur$\varphi$ with (a finite horizon subset of) PRISM, a stateoftheart symbolic model checker for Markov Chains. Our experimental results show that FHPMur$\varphi$ can handle systems that are out of reach for PRISM, namely those involving arithmetic operations on the state variables (e.g. hybrid systems).



Giuseppe Della Penna, Benedetto Intrigila, Igor Melatti, Enrico Tronci, and Marisa Venturini Zilli. "Bounded Probabilistic Model Checking with the Mur$\varphi$ Verifier." In Formal Methods in ComputerAided Design, 5th International Conference, FMCAD 2004, Austin, Texas, USA, November 1517, 2004, Proceedings, edited by A. J. Hu and A. K. Martin, 214–229. Lecture Notes in Computer Science 3312. Springer, 2004. ISSN: 3540237380. DOI: 10.1007/9783540304944_16.
Abstract: In this paper we present an explicit verification algorithm for Probabilistic Systems defining discrete time/finite state Markov Chains. We restrict ourselves to verification of Bounded PCTL formulas (BPCTL), that is, PCTL formulas in which all Until operators are bounded, possibly with different bounds. This means that we consider only paths (system runs) of bounded length. Given a Markov Chain $\cal M$ and a BPCTL formula Φ, our algorithm checks if Φ is satisfied in $\cal M$. This allows to verify important properties, such as reliability in Discrete Time Hybrid Systems. We present an implementation of our algorithm within a suitable extension of the Mur$\varphi$ verifier. We call FHPMur$\varphi$ (Finite Horizon Probabilistic Mur$\varphi$) such extension of the Mur$\varphi$ verifier. We give experimental results comparing FHPMur$\varphi$ with (a finite horizon subset of) PRISM, a stateoftheart symbolic model checker for Markov Chains. Our experimental results show that FHPMur$\varphi$ can effectively handle verification of BPCTL formulas for systems that are out of reach for PRISM, namely those involving arithmetic operations on the state variables (e.g. hybrid systems).



Giuseppe Della Penna, Benedetto Intrigila, Igor Melatti, Michele Minichino, Ester Ciancamerla, Andrea Parisse, Enrico Tronci, and Marisa Venturini Zilli. "Automatic Verification of a Turbogas Control System with the Mur$\varphi$ Verifier." In Hybrid Systems: Computation and Control, 6th International Workshop, HSCC 2003 Prague, Czech Republic, April 35, 2003, Proceedings, edited by O. Maler and A. Pnueli, 141–155. Lecture Notes in Computer Science 2623. Springer, 2003. ISSN: 3540009132. DOI: 10.1007/354036580X.
Abstract: Automatic analysis of Hybrid Systems poses formidable challenges both from a modeling as well as from a verification point of view. We present a case study on automatic verification of a Turbogas Control System (TCS) using an extended version of the Mur$\varphi$ verifier. TCS is the heart of ICARO, a 2MW Cogenerative Electric Power Plant. For large hybrid systems, as TCS is, the modeling effort accounts for a significant part of the whole verification activity. In order to ease our modeling effort we extended the Mur$\varphi$ verifier by importing the C language long double type (finite precision real numbers) into it. We give experimental results on running our extended Mur$\varphi$ on our TCS model. For example using Mur$\varphi$ we were able to compute an admissible range of values for the variation speed of the user demand of electric power to the turbogas.



Giuseppe Della Penna, Benedetto Intrigila, Igor Melatti, Enrico Tronci, and Marisa Venturini Zilli. "Finite Horizon Analysis of Stochastic Systems with the Mur$\varphi$ Verifier." In Theoretical Computer Science, 8th Italian Conference, ICTCS 2003, Bertinoro, Italy, October 1315, 2003, Proceedings, edited by C. Blundo and C. Laneve, 58–71. Lecture Notes in Computer Science 2841. Springer, 2003. ISSN: 3540202161. DOI: 10.1007/9783540452089_6.
Abstract: Many reactive systems are actually Stochastic Processes. Automatic analysis of such systems is usually very difficult thus typically one simplifies the analysis task by using simulation or by working on a simplified model (e.g. a Markov Chain). We present a Finite Horizon Probabilistic Model Checking approach which essentially can handle the same class of stochastic processes of a typical simulator. This yields easy modeling of the system to be analyzed together with formal verification capabilities. Our approach is based on a suitable disk based extension of the Mur$\varphi$ verifier. Moreover we present experimental results showing effectiveness of our approach.

