43,160 research outputs found
Exploiting path parallelism in logic programming
This paper presents a novel parallel implementation of Prolog. The system is based on Multipath, a novel execution model for Prolog that implements a partial breadth-first search of the SLD-tree. The paper focusses on the type of parallelism inherent to the execution model, which is called path parallelism. This is a particular case of data parallelism that can be efficiently exploited in a SPMD architecture. A SPMD architecture oriented to the Multipath execution model is presented. A simulator of such system has been developed and used to assess the performance of path parallelism. Performance figures show that path parallelism is effective for non-deterministic programs.Peer ReviewedPostprint (published version
D-branes and the Standard Model
We perform a systematic study of the Standard Model embedding in a D-brane
configuration of type I string theory at the TeV scale. We end up with an
attractive model and we study several phenomenological questions, such as gauge
coupling unification, proton stability, fermion masses and neutrino
oscillations. At the string scale, the gauge group is U(3)_color x U(2)_weak x
U(1)_1 x U(1)_bulk. The corresponding gauge bosons are localized on three
collections of branes; two of them describe the strong and weak interactions,
while the last abelian factor lives on a brane which is extended in two large
extra dimensions with a size of afew microns. The hypercharge is a linear
combination of the first three U(1)s. All remaining U(1)s get masses at the TeV
scale due to anomalies, leaving the baryon and lepton numbers as
(perturbatively) unbroken global symmetries at low energies. The conservation
of baryon number assures proton stability, while lepton number symmetry
guarantees light neutrino masses that involve a right-handed neutrino in the
bulk. The model predicts the value of the weak angle which is compatible with
the experiment when the string scale is in the TeV region. It also contains two
Higgs doublets that provide tree-level masses to all fermions of the heaviest
generation, with calculable Yukawa couplings; one obtains a naturally heavy top
and the correct ratio m_b/m_tau. We also study neutrino masses and mixings in
relation to recent solar and atmospheric neutrino data.Comment: 42 pages, Latex2e, 6 figures, final version to be published in Nucl.
Phys.
Finitary Deduction Systems
Cryptographic protocols are the cornerstone of security in distributed
systems. The formal analysis of their properties is accordingly one of the
focus points of the security community, and is usually split among two groups.
In the first group, one focuses on trace-based security properties such as
confidentiality and authentication, and provides decision procedures for the
existence of attacks for an on-line attackers. In the second group, one focuses
on equivalence properties such as privacy and guessing attacks, and provides
decision procedures for the existence of attacks for an offline attacker. In
all cases the attacker is modeled by a deduction system in which his possible
actions are expressed. We present in this paper a notion of finitary deduction
systems that aims at relating both approaches. We prove that for such deduction
systems, deciding equivalence properties for on-line attackers can be reduced
to deciding reachability properties in the same setting.Comment: 30 pages. Work begun while in the CASSIS Project, INRIA Nancy Grand
Es
A Practical View on Renaming
We revisit variable renaming from a practitioner's point of view, presenting
concepts we found useful in dealing with operational semantics of pure Prolog.
A concept of relaxed core representation is introduced, upon which a concept of
prenaming is built. Prenaming formalizes the intuitive practice of renaming
terms by just considering the necessary bindings, where now some passive
"bindings" x/x may be necessary as well. As an application, a constructive
version of variant lemma for implemented Horn clause logic has been obtained.
There, prenamings made it possible to incrementally handle new (local)
variables.Comment: In Proceedings WLP'15/'16/WFLP'16, arXiv:1701.0014
Compiling and securing cryptographic protocols
Protocol narrations are widely used in security as semi-formal notations to
specify conversations between roles. We define a translation from a protocol
narration to the sequences of operations to be performed by each role. Unlike
previous works, we reduce this compilation process to well-known decision
problems in formal protocol analysis. This allows one to define a natural
notion of prudent translation and to reuse many known results from the
literature in order to cover more crypto-primitives. In particular this work is
the first one to show how to compile protocols parameterised by the properties
of the available operations.Comment: A short version was submitted to IP
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