755 research outputs found
From nominal to higher-order rewriting and back again
We present a translation function from nominal rewriting systems (NRSs) to
combinatory reduction systems (CRSs), transforming closed nominal rules and
ground nominal terms to CRSs rules and terms, respectively, while preserving
the rewriting relation. We also provide a reduction-preserving translation in
the other direction, from CRSs to NRSs, improving over a previously defined
translation. These tools, together with existing translations between CRSs and
other higher-order rewriting formalisms, open up the path for a transfer of
results between higher-order and nominal rewriting. In particular, techniques
and properties of the rewriting relation, such as termination, can be exported
from one formalism to the other.Comment: 41 pages, journa
Labelled Lambda-calculi with Explicit Copy and Erase
We present two rewriting systems that define labelled explicit substitution
lambda-calculi. Our work is motivated by the close correspondence between
Levy's labelled lambda-calculus and paths in proof-nets, which played an
important role in the understanding of the Geometry of Interaction. The
structure of the labels in Levy's labelled lambda-calculus relates to the
multiplicative information of paths; the novelty of our work is that we design
labelled explicit substitution calculi that also keep track of exponential
information present in call-by-value and call-by-name translations of the
lambda-calculus into linear logic proof-nets
Assembling the Proofs of Ordered Model Transformations
In model-driven development, an ordered model transformation is a nested set
of transformations between source and target classes, in which each
transformation is governed by its own pre and post- conditions, but
structurally dependent on its parent. Following the
proofs-as-model-transformations approach, in this paper we consider a
formalisation in Constructive Type Theory of the concepts of model and model
transformation, and show how the correctness proofs of potentially large
ordered model transformations can be systematically assembled from the proofs
of the specifications of their parts, making them easier to derive.Comment: In Proceedings FESCA 2013, arXiv:1302.478
Higher-order port-graph rewriting
The biologically inspired framework of port-graphs has been successfully used
to specify complex systems. It is the basis of the PORGY modelling tool. To
facilitate the specification of proof normalisation procedures via graph
rewriting, in this paper we add higher-order features to the original
port-graph syntax, along with a generalised notion of graph morphism. We
provide a matching algorithm which enables to implement higher-order port-graph
rewriting in PORGY, thus one can visually study the dynamics of the systems
modelled. We illustrate the expressive power of higher-order port-graphs with
examples taken from proof-net reduction systems.Comment: In Proceedings LINEARITY 2012, arXiv:1211.348
Static Enforcement of Role-Based Access Control
We propose a new static approach to Role-Based Access Control (RBAC) policy
enforcement. The static approach we advocate includes a new design methodology,
for applications involving RBAC, which integrates the security requirements
into the system's architecture. We apply this new approach to policies
restricting calls to methods in Java applications. We present a language to
express RBAC policies on calls to methods in Java, a set of design patterns
which Java programs must adhere to for the policy to be enforced statically,
and a description of the checks made by our static verifier for static
enforcement.Comment: In Proceedings WWV 2014, arXiv:1409.229
Closed nominal rewriting and efficiently computable nominal algebra equality
We analyse the relationship between nominal algebra and nominal rewriting,
giving a new and concise presentation of equational deduction in nominal
theories. With some new results, we characterise a subclass of equational
theories for which nominal rewriting provides a complete procedure to check
nominal algebra equality. This subclass includes specifications of the
lambda-calculus and first-order logic.Comment: In Proceedings LFMTP 2010, arXiv:1009.218
Strategic Port Graph Rewriting: An Interactive Modelling and Analysis Framework
We present strategic portgraph rewriting as a basis for the implementation of
visual modelling and analysis tools. The goal is to facilitate the
specification, analysis and simulation of complex systems, using port graphs. A
system is represented by an initial graph and a collection of graph rewriting
rules, together with a user-defined strategy to control the application of
rules. The strategy language includes constructs to deal with graph traversal
and management of rewriting positions in the graph. We give a small-step
operational semantics for the language, and describe its implementation in the
graph transformation and visualisation tool PORGY.Comment: In Proceedings GRAPHITE 2014, arXiv:1407.767
Extending Context-Sensitivity in Term Rewriting
We propose a generalized version of context-sensitivity in term rewriting
based on the notion of "forbidden patterns". The basic idea is that a rewrite
step should be forbidden if the redex to be contracted has a certain shape and
appears in a certain context. This shape and context is expressed through
forbidden patterns. In particular we analyze the relationships among this novel
approach and the commonly used notion of context-sensitivity in term rewriting,
as well as the feasibility of rewriting with forbidden patterns from a
computational point of view. The latter feasibility is characterized by
demanding that restricting a rewrite relation yields an improved termination
behaviour while still being powerful enough to compute meaningful results.
Sufficient criteria for both kinds of properties in certain classes of rewrite
systems with forbidden patterns are presented
Principal Typings in a Restricted Intersection Type System for Beta Normal Forms with De Bruijn Indices
The lambda-calculus with de Bruijn indices assembles each alpha-class of
lambda-terms in a unique term, using indices instead of variable names.
Intersection types provide finitary type polymorphism and can characterise
normalisable lambda-terms through the property that a term is normalisable if
and only if it is typeable. To be closer to computations and to simplify the
formalisation of the atomic operations involved in beta-contractions, several
calculi of explicit substitution were developed mostly with de Bruijn indices.
Versions of explicit substitutions calculi without types and with simple type
systems are well investigated in contrast to versions with more elaborate type
systems such as intersection types. In previous work, we introduced a de Bruijn
version of the lambda-calculus with an intersection type system and proved that
it preserves subject reduction, a basic property of type systems. In this paper
a version with de Bruijn indices of an intersection type system originally
introduced to characterise principal typings for beta-normal forms is
presented. We present the characterisation in this new system and the
corresponding versions for the type inference and the reconstruction of normal
forms from principal typings algorithms. We briefly discuss the failure of the
subject reduction property and some possible solutions for it
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