A Model of Layered Architectures

Architectural styles and patterns play an important role in software engineering. One of the most known ones is the layered architecture style. However, this style is usually only stated informally, which may cause problems such as ambiguity, wrong conclusions, and difficulty when checking the conformance of a system to the style. We address these problems by providing a formal, denotational semantics of the layered architecture style. Mainly, we present a sufficiently abstract and rigorous description of layered architectures. Loosely speaking, a layered architecture consists of a hierarchy of layers, in which services communicate via ports. A layer is modeled as a relation between used and provided services, and layer composition is defined by means of relational composition. Furthermore, we provide a formal definition for the notions of syntactic and semantic dependency between the layers. We show that these dependencies are not comparable in general. Moreover, we identify sufficient conditions under which, in an intuitive sense which we make precise in our treatment, the semantic dependency implies, is implied by, or even coincides with the reflexive-transitive closure of the syntactic dependency. Our results provide a technology-independent characterization of the layered architecture style, which may be used by software architects to ensure that a system is indeed built according to that style.Comment: In Proceedings FESCA 2015, arXiv:1503.0437

Self-Reference, Biologic and the Structure of Reproduction

This paper concentrates on relationships of formal systems with biology. The paper is based on previous papers by the author. We have freely used texts of those papers where the formulations are of use, and we have extended the concepts and discussions herein considerably beyond the earlier work. We concentrate on formal systems not only for the sake of showing how there is a fundamental mathematical structure to biology, but also to consider and reconsider philosophical and phenomenological points of view in relation to natural science and mathematics. The relationship with phenomenology comes about in the questions that arise about the nature of the observer in relation to the observed that arise in philosophy, but also in science in the very act of determining the context and models upon which it shall be based.We examine the schema behind the reproduction of DNA. The DNA molecule consists of two interwound strands, the Watson Strand (W) and the Crick Strand (C). The two strands are bonded to each other via a backbone of base-pairings and these bonds can be broken by certain enzymes present in the cell. In reproduction of DNA the bonds between the two strands are broken and the two strands then acquire the needed complementary base molecules from the cellular environment to reconstitute each a separate copy of the DNA. At this level the situation can be described by a symbolism like this. DNA = -------> --------> = = DNA DNA. Here E stands for the environment of the cell. The first arrow denotes the separation of the DNA into the two strands. The second arrow denotes the action between the bare strands and the environment that leads to the production of the two DNA molecules. The paper considers and compares many formalisms for self-replication, including aspects of quantum formalism and the Temperley-Lieb algebra.Comment: LaTeX document, 71 pages, 33 figures. arXiv admin note: substantial text overlap with arXiv:quant-ph/020400

Semantics of trace relations in requirements models for consistency checking and inferencing

Requirements traceability is the ability to relate requirements back to stakeholders and forward to corresponding design artifacts, code, and test cases. Although considerable research has been devoted to relating requirements in both forward and backward directions, less attention has been paid to relating requirements with other requirements. Relations between requirements influence a number of activities during software development such as consistency checking and change management. In most approaches and tools, there is a lack of precise definition of requirements relations. In this respect, deficient results may be produced. In this paper, we aim at formal definitions of the relation types in order to enable reasoning about requirements relations. We give a requirements metamodel with commonly used relation types. The semantics of the relations is provided with a formalization in first-order logic. We use the formalization for consistency checking of relations and for inferring new relations. A tool has been built to support both reasoning activities. We illustrate our approach in an example which shows that the formal semantics of relation types enables new relations to be inferred and contradicting relations in requirements documents to be determined. The application of requirements reasoning based on formal semantics resolves many of the deficiencies observed in other approaches. Our tool supports better understanding of dependencies between requirements

Action Research : the first steps to start up a pilot experiment in heritage education

Peer-reviewedLes relacions entre els museus i les escoles canvien amb l'ús d'internet. Volem analitzar com aquestes noves relacions tenen lloc a una escala nacional. És important analitzar aquestes noves relacions possibles, que són producte de canvis socials i tecnològics, ja que permeten noves interaccions i participació, al mateix temps que demanen canvis en les formes d'organització, la gestió de recursos web i els models d'ensenyament i aprenentatge. Concretament, les xarxes d'aprenentatge poden establir una nova forma de relació entre els museus i les escoles, i els recursos educatius en línia amb contingut sobre patrimoni cultural poden oferir oportunitats d'aprenentatge i recursos de coneixement més enllà dels límits de l'ensenyament formal. Tanmateix, calen projectes experimentals per a efectuar proves i veure com aquests tipus de pràctiques d'ensenyament i aprenentatge funcionaran en un context social i cultural concret. Així, doncs, la recerca activa pot contribuir al desenvolupament d'una experiència d'aprenentatge, basat en la reflexió i l'acció. L'objectiu d'aquesta experimentació és obtenir un model de treball i millors pràctiques per a aprendre i ensenyar en xarxes d'aprenentatge formades per gestors, professors i estudiants de patrimoni en què els membres produeixin i utilitzin recursos educatius en línia amb contingut de patrimoni cultural. Els resultats d'aquest projecte empíric seran comprovats amb resultats de la primera part metodològica de la tesi doctoral per a obtenir un model que es pugui exportar a altres contextos.Las relaciones entre los museos y las escuelas cambian con el uso de internet. Queremos analizar cómo estas nuevas relaciones tienen lugar a una escala nacional. Es importante analizar estas posibles nuevas relaciones, que son producto de cambios sociales y tecnológicos, ya que permiten nuevas interacciones y participación, a la vez que requieren cambios en las formas de organización, la gestión de recursos web y los modelos de enseñanza y aprendizaje. Concretamente, las redes de aprendizaje pueden establecer una nueva forma de relación entre los museos y las escuelas, y los recursos educativos en línea con contenido de patrimonio cultural pueden ofrecer oportunidades de aprendizaje y recursos de conocimiento más allá de los límites de la enseñanza formal. No obstante, existe una necesidad de proyectos experimentales para realizar pruebas para ver cómo estos tipos de prácticas de enseñanza y aprendizaje funcionarán en un contexto social y cultural concreto. Así pues, la investigación-acción puede contribuir al desarrollo de una experiencia de aprendizaje, basado en la reflexión y las acciones. El objetivo de esta experimentación es obtener un modelo de trabajo y mejores prácticas para el aprendizaje y la enseñanza en redes de aprendizaje formadas por gestores, profesores y estudiantes del patrimonio en las que los miembros produzcan y utilicen recursos en línea con contenido de patrimonio cultural. Los resultados de este proyecto de investigación empírico serán comparados con los resultados de la primera parte metodológica de la tesis doctoral para obtener un modelo que pueda ser exportado a otros contextos.The relationships between museums and schools are changing through the use of internet. We want to analyse how these new relationships occur at a national level. It is important to analyse these possible new relationships, which are the product of social and technological changes. They allow for new interactions and participation whilst requiring changes in the forms of organisation, web resource management, and teaching and learning models. Specifically, learning networks can establish a new form of relationship between museums and schools and educational online resources with cultural heritage content can offer learning opportunities and knowledge resources beyond the boundaries of formal education. However, there is a need for experimental projects to test the evidence and to see how these kinds of teaching and learning practices will work within a concrete social and cultural context. Thus, Action Research can contribute to the development of a learning experience, based on reflection and actions. The aim of this experimentation is to obtain a working model and best practices for learning and teaching in learning networks shaped by heritage managers, teachers and students where the members produce and use educational online resources with cultural heritage content. The results of this empirical research project will be compared with results from the first methodological part of the PhD thesis to obtain a model that can be exported to other contexts

Chinese Wall Security Policy

This project establishes a Chinese wall security policy model in the environment of cloud computing. In 1988 Brewer and Nash proposed a very nice commercial security policy in British financial world. Though the policy was well accepted, but the model was incorrect. A decade later, Dr. Lin provided a model in 2003 that meets Brewer & Nash’s Policy. One of the important components in Cloud computing is data center. In order for any company to store data in the center, a trustable security policy model is a must; Chinese wall security policy model will provide this assurance. The heart of the Chinese Wall Security Policy Model is the concept of Conflict of Interest (COI). The concept can be modeled by an anti-reflexive, symmetric and transitive binary relation. In this project, by extending Dr. Lin’s Model, we explore the security issues in the environment of cloud computing and develop a small system of the Chinese Wall Security Model

What do we need to add to a social network to get a society? answer: something like what we have to add to a spatial network to get a city

Recent years have seen great advances in social network analysis. Yet, with a few exceptions, the field of network analysis remains remote from social theory. As a result, much social network research, while technically accomplished and theoretically suggestive, is essentially descriptive. How then can social networks be linked to social theory ? Here we pose the question in its simplest form: what must we add to a social network to get a society ? We begin by showing that one reason for the disconnection between network theory and society theory is that because it exists in spacetime, the concept of social network raises the issue of space in a way that is problematical for social theory. Here we turn the problem on its head and make the problem of space in social network theory explicit by proposing a surprising analogy with the question: what do you have to add to an urban space network to get a city. We show first that by treating a city as a naïve spatial network in the first instance and allowing it to acquire two formal properties we call reflexivity and nonlocality, both mediated through a mechanism we call description retrieval, we can build a picture of the dynamics processes by which collections of the buildings become living cities. We then show that by describing societies initially as social networks in space-time and adding similar properties, we can construct a plausible ontology of a simple human society

Socionic Multi-Agent Systems Based on Reflexive Petri Nets and Theories of Social Self-Organisation

This contribution summarises the core results of the transdisciplinary ASKO project, part of the German DFG's programme Sozionik, which combines sociologists' and computer scientists' skills in order to create improved theories and models of artificial societies. Our research group has (a) formulated a social theory, which is able to explain fundamental mechanisms of self-organisation in both natural and artificial societies, (b) modelled this in a mathematical way using a visual formalism, and (c) developed a novel multi-agent system architecture which is conceptually coherent, recursively structured (hence non-eclectic) and based on our social theory. The article presents an outline of both a sociological middle-range theory of social self-organisation in educational institutions, its formal, Petri net based model, including a simulation of one of its main mechanisms, and the multi-agent system architecture SONAR. It describes how the theory was created by a re-analysis of some grand social theories, by grounding it empirically, and finally how the theory was evaluated by modelling its concepts and statements.Multi-Agents Systems, Petri Nets, Self-Organisation, Social Theories

Extending the Calculus of Constructions with Tarski's fix-point theorem

We propose to use Tarski's least fixpoint theorem as a basis to define recursive functions in the calculus of inductive constructions. This widens the class of functions that can be modeled in type-theory based theorem proving tool to potentially non-terminating functions. This is only possible if we extend the logical framework by adding the axioms that correspond to classical logic. We claim that the extended framework makes it possible to reason about terminating and non-terminating computations and we show that common facilities of the calculus of inductive construction, like program extraction can be extended to also handle the new functions