We propose a transformation system for Constraint Logic Programming (CLP) programs and modules. The framework is inspired by the one of Tamaki and Sato (1984) for pure logic programs. However, the use of CLP allows us to introduce some new operations such as splitting and constraint replacement. We provide two sets of applicability conditions. The first one guarantees that the original and the transformed programs have the same computational behaviour, in terms of answer constraints. The second set contains more restrictive conditions that ensure compositional#y: we prove that under these conditions the original and the transformed modules have the same answer constraints also when they are composed with other modules. This result is proved by first introducing a new formulation, in terms of trees, of a resultants semantics for CLP. As corollaries we obtain the correctness of both the modular and the nonmodular system w.r.t, the least model semantics.

. LKHW : a directed diffusionbased secure multicast scheme for wireless sensor networks. In 32nd International Conference on Parallel Processing Workshops (Proceedings ICPP 2003 Workshops, Kaohsiung, Taiwan, October 6-9, 2003. IEEE Computer Society. DOI: 10.1109/ICPPW.2003 General rights Copyright and moral rights for the publications made accessible in the public portal are retained by the authors and/or other copyright owners and it is a condition of accessing publications that users recognise and abide by the legal requirements associated with these rights.• Users may download and print one copy of any publication from the public portal for the purpose of private study or research.• You may not further distribute the material or use it for any profit-making activity or commercial gain • You may freely distribute the URL identifying the publication in the public portal ? Take down policyIf you believe that this document breaches copyright please contact us providing details, and we will remove access to the work immediately and investigate your claim.

We study the termination properties of well-moded programs, and we show thz, t. under suitable conditions, for these programs there exists an algebraic characteriza zion-in the style of Apt and Pedreschi, Studies in pure prolog: termination, in: J.W. Lloyd ted.), Proceedings of the Simposium in Computational Logic, Springer. Berlin. 1990. pp. 150-176-of the property of being terminating. This characterization enjoys the prorberties of being compositional and. to some extent, of being easy to check.

We propose a constraint-based system for the verification of security protocols that improves upon the one developed by Millen and Shmatikov [30]. Our system features (1) a significantly more efficient implementation, (2) a monotonic behavior, which also allows to detect flaws associated to partial runs and (3) a more expressive syntax, in which a principal may also perform explicit checks. In this paper we also show why these improvements yield a more effective and practical system.