Refinement in hybridised institutions

Hybrid logics, which add to the modal description of transition structures the ability to refer to specific states, offer a generic framework to approach the specification and design of reconfigurable systems, i.e., systems with reconfiguration mechanisms governing the dynamic evolution of their execution configurations in response to both external stimuli or internal performance measures. A formal representation of such systems is through transition structures whose states correspond to the different configurations they may adopt. Therefore, each node is endowed with, for example, an algebra, or a first-order structure, to precisely characterise the semantics of the services provided in the corresponding configuration. This paper characterises equivalence and refinement for these sorts of models in a way which is independent of (or parametric on) whatever logic (propositional, equational, fuzzy, etc) is found appropriate to describe the local configurations. A Hennessy–Milner like theorem is proved for hybridised logics.This work is funded by ERDF-European Regional Development Fund, through the COMPETE Programme, and by National Funds through FCT within project FCOMP-01-0124-FEDER-028923 and by project NORTE-07-0124-FEDER-000060, co-financed by the North Portugal Regional Operational Programme (ON.2), under the National Strategic Reference Framework (NSRF), through the European Regional Development Fund (ERDF). The work had also partial financial assistance by the project PEst-OE/MAT/UI4106/2014 at CIDMA, FCOMP-01-0124-FEDER-037281 at INESC TEC and the Marie Curie project FP7-PEOPLE-2012-IRSES (GetFun)

Bisimilarity and refinement for hybrid(ised) logics

The complexity of modern software systems entails the need for reconfiguration mechanisms governing the dynamic evolution of their execution configurations in response to both external stimulus or internal performance measures. Formally, such systems may be represented by transition systems whose nodes correspond to the different configurations they may assume. Therefore, each node is endowed with, for example, an algebra, or a first-order structure, to precisely characterise the semantics of the services provided in the corresponding configuration. Hybrid logics, which add to the modal description of transition structures the ability to refer to specific states, offer a generic framework to approach the specification and design of this sort of systems. Therefore, the quest for suitable notions of equivalence and refinement between models of hybrid logic specifications becomes fundamental to any design discipline adopting this perspective. This paper contributes to this effort from a distinctive point of view: instead of focussing on a specific hybrid logic, the paper introduces notions of bisimilarity and refinement for hybridised logics, i.e. standard specification logics (e.g. propositional, equational, fuzzy, etc) to which modal and hybrid features were added in a systematic way.FC

A logic for n-dimensional hierarchical refinement

Hierarchical transition systems provide a popular mathematical structure to represent state-based software applications in which different layers of abstraction are represented by inter-related state machines. The decomposition of high level states into inner sub-states, and of their transitions into inner sub-transitions is common refinement procedure adopted in a number of specification formalisms. This paper introduces a hybrid modal logic for k-layered transition systems, its first-order standard translation, a notion of bisimulation, and a modal invariance result. Layered and hierarchical notions of refinement are also discussed in this setting.Comment: In Proceedings Refine'15, arXiv:1606.0134

From partnership to firm:Hybridity as source of routine change

Strategic partnerships have recently gained foothold in the Danish construction industry as a novel collaborative interorganisational relationship. Strategic partnerships have so far been used in major construction programmes and can be seen as a hybridised organisational form that draws on multiple existing organisational forms in creating new interorganisational routines and developing collective knowledge. The objective of the paper is to explore how a strategic partnership creates new routines by developing collective knowledge, and how these routines are transferred to the constituent organisations as firm-specific routines. Empirically, we draw on data from a strategic partnership between the City of Copenhagen\u27s client unit, ByK, and a group of six AEC firms that constitutes the consortium named TRUST. Data is collected in the period 2017-2019 and consists of 22 interviews describing developments in the strategic partnership and in the constituent firms. In the analysis, we apply an institutional theory perspective in a parallel analysis of developments in the strategic partnership and in two of the constituent firms (the client and the contractor). We show that the strategic partnership creates new interorganisational routines in pursuit of collective knowledge and that the constituent firms learn from their engagement in the strategic partnership, which leads to creation of new routines and changes in existing routines. As such, the paper contributes to an understanding of how new intraorganisational routines created in a strategic partnership ramify to firm-specific routines in the constituent firms

Foundations and techniques for software reconfigurability

Programa de doutoramento em Informática das Universidades do Minho, de Aveiro e do PortoThe qualifier reconfigurable is used for software systems which behave differently in different modes of operation (often called configurations) and commute between them along their lifetime. Such systems, which evolve in response to external or internal stimulus, are everywhere: from e-Health or e-Government integrated services to sensor networks, from domestic appliances to complex systems distributed and collaborating over the web, from safety or mission-critical applications to massive parallel software. There are two basic approaches to formally capture requirements of this sort of systems: one emphasizes behaviour and its evolution; the other focus on data and their transformations. Within the first paradigm, reconfigurable systems are regarded as (some variant of) state-machines whose states correspond to the different configurations they may assume. On the other hand, in data-oriented approaches the system’s functionality is specified in terms of input-output relations modelling operations on data. A specification presents a theory in a suitable logic, expressed over a signature which captures its syntactic interface. Its semantics is a class of concrete algebras or relational structures, acting as models for the specified theory. The observation that whatever services a reconfigurable system may offer, at each moment, may depend on the stage of its evolution, suggests that both dimensions (data and behaviour) are interconnected and should be combined. In particular, each node in the transition system which describes a reconfiguration space, may be endowed with a local structure modelling the functionality of the respective configuration. This is the basic insight of a configurations-as-local-models specification style. These specifications are modeled by structured state-machines, states denoting complex structures, rather than sets. A specification for this sort of system should be able to make assertions both about the transition dynamics and, locally, about each particular configuration. This leads to the adoption of hybrid logic, which adds to the modal description of transition structures the ability to refer to specific states, as the lingua franca for a suitable specification method. On the other hand, specific applications may require specific logics to describe their configurations. For example, requirements expressed equationally lead to a configurations-as-algebras perspective. But depending on their nature one could also naturally end up in configurations-as-relational-structutres, or probabilistic spaces or even in configurations-as-Kripke-structutres, if first-order, fuzzy or modal logic is locally used. The aim of this thesis is to develop the foundations for a specification method based on these principles. To subsume all the possibilities above our approach builds on very general grounds. Therefore, instead of committing to a particular version of hybrid logic, we start by choosing a specific logic for expressing requirements at the configuration (static) level. This is later taken as the base logic on top of which the characteristic features of hybrid logic, both at the level of syntax (i.e. modalities, nominals, etc.) and of the semantics (i.e. possible worlds), are developed. This process is called hybridisation and is one of the main technical contributions of this thesis. To be completely general, it is framed in the context of the theory of institutions of J. Goguen and R. Burstall, each logic (base and hybridised) being treated abstractly as an institution. In this setting the thesis’ contributions are the following: A method to hybridise arbitrary institutions; this can be understood as a source of logics to support arbitrary configurations-as-local-models specifications. A method to lift encodings (technically, comorphisms) from an institution to a presentation in first-order logic, into encodings from its hybridisation to a presentation in first-order logic; this result paves the way to the introduction of suitable automatised proof support for a wide range of hybridised logics. Suitable characterisations of bisimulation and refinement for models of (generic) hybridisations, which provide canonical, satisfaction preserving relations to identify and relate models. A two-stage specification method for reconfigurable systems based on a global transition structure to capture the system’s reconfiguration space, and a local specification of configurations in whatever logic is found expressive enough for the requirements at hands. A set of additional technics to assist the process of specifying and verifying requirements for reconfigurable systems, with partial tool support.O termo reconfigurável é usado para sistemas de software que se comportam de forma diferente em diferentes modos de operação (frequentemente chamados de configurações) comutando entre eles, ao longo do seu ciclo de vida. Estes sistemas, que evoluem em resposta a estímulos externos e internos, estão por toda a parte, desde sistemas de e-Health ou sistemas integrados de e-Governement, às redes de sensores, das aplicações domésticas aos complexos sistemas distribuidos, dos sistemas críticos de missão ao software de computação paralela. Existem duas abordagens formais para captar requisitos deste tipo de sistemas: uma focada no comportamento e evolução; e outra focada nos dados e respectivas transformações. Segundo o primeiro paradigma, os sistemas reconfiguráveis são abordados por (alguma variante) de máquinas-de-estados, correspondendo, cada um dos seus estados, a uma configuração que o sistema possa assumir. A outra abordagem, orientada aos dados, especifica as funcionalidades do sistema em função de relações de input-output, que modelam operações nos dados. Uma especificação apresenta uma teoria numa lógica adequada, expressa sobre uma assinatura que capta a sua interface sintática. A sua semântica consiste na classe de álgebras, ou estruturas de primeira ordem, que modelam a teoria especificada. A observação de que, a cada momento, os serviços oferecidos por um sistema reconfigurável possam depender do estado da sua evolução, sugere-nos que ambas as dimensões (dados e comportamento) estejam interligados e devam ser combinados. Em particular, cada nó do sistema de transição, que descreve o espaço de reconfigurabilidade, pode ser dotado de uma estrutura local onde as funcionalidades do sistema, na respectiva configuração, são modeladas. Esta é a ideia base da especificação configurações-como-modeloslocais. Tecnicamente, as especificações são modeladas por máquinas de estados estruturadas, onde cada estado denota uma estrutura complexa, ao invés de um conjunto. Uma especificação para este tipo de sistemas deve ser adequada à expressão de asserções acerca da dinâmica de transições, assim como, ao nível local de cada configuração particular. Isto leva-nos à adopção de lógica híbrida, que adiciona, mecanismos para referir estados específicos à expressividade modal dos sistemas de transição, como lingua franca para um método adequado de especificação. Por outro lado, aplicações podem requerer lógicas específicas para descrever as suas configurações. Por exemplo, requisitos expressos por equações devem ser modelados numa perspectiva configurações-como-álgebras. Dependendo da sua natureza, podemos considerar configurações-como-estruturas de primeira ordem, ou configurações-como-espaços probabilísticos ou mesmo configurações-como-estruturas de Kripke quando usadas, localmente, lógica de primeira ordem, lógica fuzzy, ou lógica modal respectivamente. O objectivo da tese é desenvolver os fundamentos para um método de especificação baseado nestes princípios. Por forma a acomodar todas estas possibilidades, a abordagem é desenvolvida sob fundamentos muito genéricos. Ao invés de comprometer a abordagem com uma lógica híbrida particular, partimos da escolha da lógica específica para especificar requisitos ao nível (estáctico) local. Esta lógica é então tomada como lógica de base, sobre a qual os mecanismos da lógica híbrida, tanto ao nível sintáctico (i.e., modalidades, nominais, etc.) como ao semântico (i.e., mundos possíveis), são desenvolvidos. Este processo, que chamamos de hibridização, é uma das principais contribuições técnicas da tese. A generalidade do método resulta do seu desenvolvimento no contexto da teoria das instituições de J. Goguen e R. Burstall. As peincipais contribuições da tese são: • um método para hibridizar instituições arbitrárias; o que pode ser entendido como uma fonte de lógicas para suportar especificações configurações- como-modelos-locais arbitrárias • um método para transportar codificações de uma instituição nas apresentações de primeira ordem (tecnicamente comorfismos), em codificações da sua hibridização em apresentações em primeira ordem; este resultado abre o caminho para a introdução do suporte de prova automático para uma ampla classe de lógicas híbridas; • caracterização de relações de bissimulação e de refinamento para modelos de hibridizações genéricas. Isto oferece relações canónicas, que preservam satisfação, para identificar e relacionar modelos; • um método de especificação para sistemas reconfiguráveis com dois estágios, baseado numa estrutura de transição global, onde o espaço de reconfigurações do sistema é modelado; e numa especificação local das configurações expressa numa lógica escolhida como adequada, aos requisitos a tratar; • um conjunto de técnicas adicionais para assistir o processo de especificação e de verificação de requisitos de sistemas reconfiguráveis com suporte parcial de ferramentas.Fundação para a Ciência e Tecnologia (FCT) and Critical Software S.A., under BDE grant under the contract SFRH/BDE/33650/2009 and by the MONDRIAN Project (FCT) under the contract PTDC/EIA-CCO/108302/2008

Asymmetric Combination of Logics is Functorial: A Survey

Asymmetric combination of logics is a formal process that develops the characteristic features of a specific logic on top of another one. Typical examples include the development of temporal, hybrid, and probabilistic dimensions over a given base logic. These examples are surveyed in the paper under a particular perspective—that this sort of combination of logics possesses a functorial nature. Such a view gives rise to several interesting questions. They range from the problem of combining translations (between logics), to that of ensuring property preservation along the process, and the way different asymmetric combinations can be related through appropriate natural transformations

Layered logics, coalgebraically

This short note revisits layered logics from a coalgebraic point of view, and proposes a naturality condition to express the typical hierarchical requirement under which all abstract transitions should be traceable in more specialised layers.NORTE-01-0145-FEDER-000037. ERDF - European Regional Development Fund through the Operational Programme for Competitiveness and Internationalisation through (a) COMPETE 2020 Programme and by National Funds through the Portuguese funding agency, FCT - Fundação para a Ciência e a Tecnologia, project POCI-01-0145-FEDER-016826, and (b) Norte Portugal Regional Operational Programme (NORTE 2020), under the PORTUGAL 2020 Partnership Agreement, within project NORTE-01-0145-FEDER-00003

Liberal ethnicity: beyond liberal nationalism and minority rights

This article tries to make the case for a variant of the good life based on a synthesis of liberalism and ethnicity. Liberal communitarianism's treatment of ethnicity tends to fall under the categories of either liberal culturalism or liberal nationalism. Both, it is argued, fail to come to terms with the reality of ethnic community, preferring instead to define ethnicity in an unrealistic, cosmopolitan manner. By contrast, this essay squarely confronts four practices that are central to ethnic communities: symbolic boundary-maintenance; exclusive and inflexible mythomoteurs ; the use of ancestry and race as boundary markers; and the desire among national groups to maintain their ethnic character. This article argues that none of these practices need contravene the tenets of liberalism as long as they are reconstructed so as to minimize entry criteria and decouple national ethnicity from the state. The notion of liberal ethnicity thereby constitutes an important synthesis of liberal and communitarian ends

The dynamics of managing people in the diverse cultural and institutional context of Africa

Purpose The purpose of this article is to introduce the special issue which considers some of the contemporary debates in managing people in Africa. Design/methodology/approach The papers that constitute this special issue were selected from submissions to various events hosted by the Africa Research Group, a community of scholars committed to researching Africa, and from a more general call for submissions. Findings The papers highlight the changing picture of the African organisational landscape and provide both theoretical and empirical insights about the opportunities and challenges of managing people in a culturally complex continent. Originality/value Taken together, the papers make an important contribution by engaging current debates and demonstrating potential new areas for further research