5,602 research outputs found
Semantic Predicate Types and Approximation for Class-based Object Oriented Programming
We apply the principles of the intersection type discipline to the study of
class-based object oriented programs and; our work follows from a similar
approach (in the context of Abadi and Cardelli's Varsigma-object calculus)
taken by van Bakel and de'Liguoro. We define an extension of Featherweight
Java, FJc and present a predicate system which we show to be sound and
expressive. We also show that our system provides a semantic underpinning for
the object oriented paradigm by generalising the concept of approximant from
the Lambda Calculus and demonstrating an approximation result: all expressions
to which we can assign a predicate have an approximant that satisfies the same
predicate. Crucial to this result is the notion of predicate language, which
associates a family of predicates with a class.Comment: Proceedings of 11th Workshop on Formal Techniques for Java-like
Programs (FTfJP'09), Genova, Italy, July 6 200
Modal logics for reasoning about object-based component composition
Component-oriented development of software supports the adaptability and maintainability of large systems, in particular if requirements change over time and parts of a system have to be modified or replaced. The software architecture in such systems can be described by components
and their composition. In order to describe larger architectures, the composition concept becomes crucial. We will present a formal framework for component composition for object-based software development. The deployment of modal logics for defining components and component composition will allow us to reason about and prove properties of components and compositions
Pattern matching in compilers
In this thesis we develop tools for effective and flexible pattern matching.
We introduce a new pattern matching system called amethyst. Amethyst is not
only a generator of parsers of programming languages, but can also serve as an
alternative to tools for matching regular expressions.
Our framework also produces dynamic parsers. Its intended use is in the
context of IDE (accurate syntax highlighting and error detection on the fly).
Amethyst offers pattern matching of general data structures. This makes it a
useful tool for implementing compiler optimizations such as constant folding,
instruction scheduling, and dataflow analysis in general.
The parsers produced are essentially top-down parsers. Linear time complexity
is obtained by introducing the novel notion of structured grammars and
regularized regular expressions. Amethyst uses techniques known from compiler
optimizations to produce effective parsers.Comment: master thesi
Observation and abstract behaviour in specification and implementation of state-based systems
Classical algebraic specification is an accepted framework for specification. A criticism which applies is the
fact that it is functional, not based on a notion of state as most software development and implementation languages
are. We formalise the idea of a state-based object or abstract machine using algebraic means. In contrast to similar approaches we consider dynamic logic instead of equational logic as the framework for specification and implementation. The advantage is a more expressive language allowing us to specify safety and liveness conditions. It also allows a clearer distinction of functional and state-based parts which require different treatment in order to achieve behavioural abstraction when necessary. We shall in particular focus on abstract behaviour and observation. A behavioural notion of satisfaction for state-elements is needed in order to abstract from irrelevant details of the state realisation
Reducing the Number of Annotations in a Verification-oriented Imperative Language
Automated software verification is a very active field of research which has
made enormous progress both in theoretical and practical aspects. Recently, an
important amount of research effort has been put into applying these techniques
on top of mainstream programming languages. These languages typically provide
powerful features such as reflection, aliasing and polymorphism which are handy
for practitioners but, in contrast, make verification a real challenge. In this
work we present Pest, a simple experimental, while-style, multiprocedural,
imperative programming language which was conceived with verifiability as one
of its main goals. This language forces developers to concurrently think about
both the statements needed to implement an algorithm and the assertions
required to prove its correctness. In order to aid programmers, we propose
several techniques to reduce the number and complexity of annotations required
to successfully verify their programs. In particular, we show that high-level
iteration constructs may alleviate the need for providing complex loop
annotations.Comment: 15 pages, 8 figure
Web and Semantic Web Query Languages
A number of techniques have been developed to facilitate
powerful data retrieval on the Web and Semantic Web. Three categories
of Web query languages can be distinguished, according to the format
of the data they can retrieve: XML, RDF and Topic Maps. This article
introduces the spectrum of languages falling into these categories
and summarises their salient aspects. The languages are introduced using
common sample data and query types. Key aspects of the query
languages considered are stressed in a conclusion
Knowledge Representation Concepts for Automated SLA Management
Outsourcing of complex IT infrastructure to IT service providers has
increased substantially during the past years. IT service providers must be
able to fulfil their service-quality commitments based upon predefined Service
Level Agreements (SLAs) with the service customer. They need to manage, execute
and maintain thousands of SLAs for different customers and different types of
services, which needs new levels of flexibility and automation not available
with the current technology. The complexity of contractual logic in SLAs
requires new forms of knowledge representation to automatically draw inferences
and execute contractual agreements. A logic-based approach provides several
advantages including automated rule chaining allowing for compact knowledge
representation as well as flexibility to adapt to rapidly changing business
requirements. We suggest adequate logical formalisms for representation and
enforcement of SLA rules and describe a proof-of-concept implementation. The
article describes selected formalisms of the ContractLog KR and their adequacy
for automated SLA management and presents results of experiments to demonstrate
flexibility and scalability of the approach.Comment: Paschke, A. and Bichler, M.: Knowledge Representation Concepts for
Automated SLA Management, Int. Journal of Decision Support Systems (DSS),
submitted 19th March 200
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