1,720,969 research outputs found
On Unfolding Completeness for Rewriting Logic Theories
Full text linkMany transformation systems for program optimization, program synthesis, and program specialization are based on fold/unfold transformations. In this paper, we investigate the semantic properties of a narrowing-based unfolding transformation that is useful to transform rewriting logic theories. We also present a transformation methodology that is able to determine whether an unfolding transformation step would cause incompleteness and avoid this problem by completing the transformed rewrite theory with suitable extra rules. More precisely, our methodology identifies the sources of incompleteness and derives a set of rules that are added to the transformed rewrite theory in order to preserve the semantics of the original theory.Alpuente Frasnedo, M.; Baggi, M.; Ballis, D.; Falaschi, M. (2010). On Unfolding Completeness for Rewriting Logic Theories. https://riunet.upv.es/handle/10251/863
PHIL: A Lazy Implementation of a Language for Approximate Filtering of XML Documents
No full textIn this paper, we introduce a system, written in Haskell, for filtering information from XML data. Essentially,
the system implements a simple declarative language which allows one to extract relevant data as well as to exclude useless and misleading contents from an XML document by matching patterns against XML documents.
The matching mechanism employes a cost-based pattern transformation algorithm which searches for patterns in an approximate way (i.e. modulo renaming, insertion, and deletion of XML items) and ranks the results w.r.t. their cost. In order to improve efficiency, the implementation uses sophisticated indexing techniques and exploits laziness to automatically avoid the construction of unnecessary data structures. We analyzed both the expressiveness of our filtering language and the performance of the system using the well known XMark benchmark suite
Semantic Verification of Web System Contents
No full textIn this paper, we present a rule-based specification language to define and automatically check semantic as well as syntactic constraints over the informative content of a Web system. The language is inspired by the GVERDI language and significantly extends it by integrating ontology reasoning into the specification rules and by adding new syntactic constructs. The resulting language increases the expressiveness of the original one and enables a more sophisticated treatment of the semantic information related to the contents of the Web system
Quantitative Pathway Logic for Computational Biology
No full textThis paper presents an extension of Pathway Logic, called Quantitative Pathway Logic (QPL), which allows one to reason about quantitative aspects of biological processes, such as element concentrations and reactions kinetics. Besides, it supports the modeling of inhibitors, that is, chemicals which may block a given reaction whenever their concentration exceeds a certain threshold. QPL models can be specified and directly simulated using rewriting logic or can be translated into Discrete Functional Petri Nets (DFPN) which are a subclass of Hybrid Functional Petri Nets in which only discrete transitions are allowed. Under some constraints over the anonymous variables appearing in the QPL models, the transformation between the two computational models is shown to preserve computations. By using the DFPN representation our models can be graphically visualized and simulated by means of well known tools (e.g. Cell Illustrator); moreover standard Petri net analyses (e.g. topological analysis, forward/backward reachability, etc.) may be performed on the net model. An executable framework for QPL and for the translation of QPL models into DFPNs has been implemented using the rewriting-based language Maude. We have tested this system on several examples
A fold/unfold transformation framework for rewrite theories extended to CCT
No full textMany transformation systems for program optimization, program synthesis, and program specialization are based on fold/unfold transformations. In this paper, we present a fold/unfold-based transformation framework for rewriting logic theories which is based on narrowing. For the best of our knowledge, this is the first fold/unfold transformation framework which allows one to deal with functions, rules, equations, sorts, and algebraic laws (such as commutativity and associativity).
We provide correctness results for the transformation system w.r.t.
the semantics of ground reducts.
Moreover, we show how our transformation technique can be naturally
applied to implement a Code Carrying Theory (CCT) system.
CCT is an approach for securing delivery of code from a producer to a consumer
where only a certificate (usually in the form of assertions and proofs)
is transmitted from the producer to the consumer who can check its validity and
then extract executable code from it. Within our framework, the certificate
consists of a sequence of transformation steps which can be applied to
a given consumer specification in order to automatically synthesize safe
code in agreement with the original requirements.
We also provide an implementation of the program transformation framework
in the high--performance, rewriting logic language Maude
which, by means of
an experimental evaluation of the system,
highlights the potentiality of our approach
An Access Control Language based on Term Rewriting and Description Logic
No full textThis paper presents a rule-based, domain specific language for modeling access control policies which is particularly suitable for managing security in the semantic web, since (i) it allows one to evaluate authorization requests according to semantic information retrieved from remote knowledge bases; (ii) it supports semantic-based policy composition, delegation and closure via flexible operators which can be defined by security administrators in a pure declarative way with little effort. The operational engine of the language smoothly integrates description logic into standard term rewriting giving support to reasoning capabilities which are particularly useful in this context, since they allow one to naturally combine and reuse data extracted from multiple knowledge bases. Such a rewrite engine can be used to evaluate authorization requests w.r.t. a policy specification as well as to formally check properties regarding the security domain to be protected. The language we propose has been implemented in a prototypical system, which is written in Haskell. Some case studies have been analyzed to highlight the potentiality of our approach
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
- …
