Characterising Deadlines in Temporal Modal Defeasible Logic

We provide a conceptual analysis of several kinds of deadlines, represented in Temporal Modal Defeasible Logic. The paper presents a typology of deadlines, based on the following parameters: deontic operator, maintenance or achievement, presence or absence of sanctions, and persistence after the deadline. The deadline types are illustrated by a set of examples

Extending rely-guarantee thinking to handle real-time scheduling

The reference point for developing any artefact is its specification; to develop software for- mally, a formal specification is required. For sequential programs, pre and post conditions (together with abstract objects) suffice; rely and guarantee conditions extend the scope of formal development approaches to tackle concurrency. In addition, real-time systems need ways of both requiring progress and relating that progress to some notion of time. This paper extends rely-guarantee ideas to cope with specifications of—and assumptions about— real-time schedulers. Furthermore it shows how the approach helps identify and specify fault-tolerance aspects of such schedulers by systematically challenging the assumption

Extending Event-B with discrete timing properties

Event-B is a formal language for systems modelling, based on set theory and predicate logic. It has the advantage of mechanized proof, and it is possible to model a system in several levels of abstraction by using refinement. Discrete timing properties are important in many critical systems. However, modelling of timing properties is not directly supported in Event-B. In this work, we identify three main categories of discrete timing properties for trigger response patterns, deadline, delay and expiry. We introduce language constructs for each of these timing properties that augment the Event-B language. We describe how these constructs have been given a semantics in terms of the standard Event-B constructs. To ease the process of using timing properties in a refinement-based development, we introduce patterns for refining the timing constructs that allow timing properties on abstract models to be replaced by timing properties on refined models. The language constructs and refinement patterns are illustrated through some generic examples.We have developed a tool to support our approach. Our tool is a plug-in to the Rodin tool-set for Event-B and automates the translation of timing properties to Event-B as well as the generation of gluing invariants, required to verify the consistency of timing properties refinement. In the end, we demonstrate the practicality of our approach, by going through the modelling and verifying process of two real-time case studies. The main focus will be the usefulness of the timing refinement patterns in a step-wise modelling and verification process of a real-time system

Electronic institutions with normative environments for agent-based E-contracting

Tese de doutoramento. Engenharia Informática. Faculdade de Engenharia. Universidade do Porto. 201

A Rewriting Framework for Activities Subject to Regulations

Activities such as clinical investigations or financial processes are subject to regulations to ensure quality of results and avoid negative consequences. Regulations may be imposed by multiple governmental agencies as well as by institutional policies and protocols. Due to the complexity of both regulations and activities there is great potential for violation due to human error, misunderstanding, or even intent. Executable formal models of regulations, protocols, and activities can form the foundation for automated assistants to aid planning, monitoring, and compliance checking. We propose a model based on multiset rewriting where time is discrete and is specified by timestamps attached to facts. Actions, as well as initial, goal and critical states may be constrained by means of relative time constraints. Moreover, actions may have non-deterministic effects, that is, they may have different outcomes whenever applied. We demonstrate how specifications in our model can be straightforwardly mapped to the rewriting logic language Maude, and how one can use existing techniques to improve performance. Finally, we also determine the complexity of the plan compliance problem, that is, finding a plan that leads from an initial state to a desired goal state without reaching any undesired critical state. We consider all actions to be balanced, that is, their pre and post-conditions have the same number of facts. Under this assumption on actions, we show that the plan compliance problem is PSPACE-complete when all actions have only deterministic effects and is EXPTIME-complete when actions may have non-deterministic effects

State Capacity and Non-state Service Provision in Fragile and Conflict-affected States

How can governments effectively engage with non-state providers (NSPs) of basic services where capacity is weak? This paper examines whether and how fragile and conflict affected states can co-ordinate, finance, and set and apply standards for the provision of basic services by NSPs. It explores ways of incrementally engaging the state, beginning with activities that are least likely to do harm to non-state provision. Through the ‘indirect’ roles of setting the policy environment and engaging in policy dialogue, regulating and facilitating, contracting, and entering into mutual and informal agreements with NSPs, the state can in principle assume responsibility for the provision of basic services without necessarily being involved in direct provision. But government capacity to perform these roles is constrained by the state’s weak legitimacy, coverage and competence, lack of basic information about the non-state sector, and lack of basic organisational capacity to form and maintain relationships with NSPs. The experience of the exercise of the indirect roles in fragile settings suggests: * Governments may be more willing to engage with NSPs where there is recognition that government cannot alone deliver all services, where public and private services are not in competition, and where there is evidence that successful collaboration is possible (demonstrated through small-scale pilots). * The extent to which engagements are ‘pro-service’may be influenced by government motives for engagement and the extent to which the providers that are most important to poor people are engaged. * Formal policy dialogue between government and NSPs may be imperfect, unrepresentative and at times unhelpful in fragile settings. Informal dialogue - at the operational level - could more likely be where synergies can be found. * Regulation is more likely to be ‘pro-service’ where it offers incentives for compliance, and where it focuses on standards in terms of outputs and outcomes rather than inputs and entry controls. * Wide scale, performance-based contracting has been successful in delivering services in some cases, but the sustainability of this approach is often questioned. Some successful contractual agreements have a strong informal, relational element and grow out of earlier informal connections. * Informal and mutual agreements can avoid the capacity problems and tensions implicit in formal contracting but may present problems of non-transparency and exclusion of competition. Paradoxically, the need for large-scale approaches and quick co-ordination of services in fragile and conflict-affected settings may require ‘prematurely high’ levels of state-NSP engagement, before the development of the underlying institutional structures that would support them. When considering strategies to support the capacity of government to engagement with NSPs, donors should: * Recognise non-state service provision and adopt the ‘do no harm’ principle: It would be wrong to set the ambition of 'managing ‘ non-state provision in its entirety, and it can be very harmful for low-capacity states to seek to regulate all NSP or to draw it into clumsy contracts. * Beware of generalisation: Non-state provision takes many forms in response to different histories and to political and economic change. The possibilities and case for state engagement have to be assessed not assumed. The particular identities of NGOs and enterprises should be considered. * Recognise that state building can occur through any of the types of engagement with NSPs: Types of engagement should therefore be selected on the basis of their likely effectiveness in improving service delivery. * Begin with less risky/small scale forms of engagement where possible: State interventions that imply a direct controlling role for the state and which impose obligations on NSPs (i.e. contracting and regulation) require greater capacity (on both sides) and present greater risk of harm if performed badly than the roles of policy dialogue and entering into mutual agreements. * Adopt mixed approaches: The choice between forms of engagement does not have to be absolute. Rather than adopting a uniform plan of engagement in a particular country, it may be better to try different approaches in different regions or sectors

How coordination trajectories influence the performance of interorganizational project networks

This study examines how the joint use of integrators and contracts either enables or hampers coordination and, in turn, the performance of interorganizational project networks. Using extensive qualitative analyses and socio-metric techniques, we investigated coordination among organizations during seven small and medium-sized building projects. Our longitudinal study reveals how integrators develop connecting functions that, together with contracts' steering functions, largely drive coordination dynamics. Further data analyses provide insight into how coordination hinges on the prevalence of connecting or steering, which may more or less fit with coordination needs in various project phases. Given these findings, we theorize the contingent nature of the interplay between the use of integrators and contracts throughout projects. Our findings are integrated into a process model of how coordination trajectories lead to different performance levels of interorganizational project networks. Our study has theoretical implications for the literature on project-based organizing and, more broadly, the literature on interorganizational coordination. (17) How Coordination Trajectories Influence the Performance of Interorganizational Project Networks. Available from: https://www.researchgate.net/publication/316692856_How_Coordination_Trajectories_Influence_the_Performance_of_Interorganizational_Project_Networks [accessed Sep 27, 2017]