Abstract
Programmers and support engineers typically rely on log data to narrow down the root cause of unexpected behaviors in dependable distributed systems. Unfortunately, the inherently distributed nature and complexity of such distributed executions often leads to multiple independent logs, scattered across different physical machines, with thousands or millions entries poorly correlated in terms of event causality. This renders log-based debugging a tedious, time-consuming, and potentially inconclusive task. We present Falcon, a tool aimed at making log-based analysis of distributed systems practical and effective. Falcon's modular architecture, designed as an extensible pipeline, allows it to seamlessly combine several distinct logging sources and generate a coherent space-time diagram of distributed executions. To preserve event causality, even in the presence of logs collected from independent unsynchronized machines, Falcon introduces a novel happens-before symbolic formulation and relies on an off-the-shelf constraint solver to obtain a coherent event schedule. Our case study with the popular distributed coordination service Apache Zookeeper shows that Falcon eases the log-based analysis of complex distributed protocols and is helpful in bridging the gap between protocol design and implementation.

Abstract
The development of smart mobility initiatives requires specialized and contextualized policies addressing the needs and interests of many stakeholders involved. Since the development of such policies is challenging, there is a need to learn from the experience of many cities around the world offering efficient and successfully adopted smart mobility services. However, in practice, the information provided about such initiatives is shallow and unstructured. To address this issue, we study the state of the art in mobility services, reviewing scientific publications and 42 smart mobility services delivered by nine smart cities around the world, and we propose a taxonomy for planning and designing smart mobility services. The taxonomy provides a common vocabulary to discuss and share information about such services. It comprises eight dimensions: type of services, maturity level, users, applied technologies, delivery channels, benefits, beneficiaries, and common functionality. The contribution of the proposed taxonomy is to serve as a tool for guiding policy makers by identifying a spectrum of mobility services that can be provided, to whom, what technologies can be used to deliver them, and what is the delivered public value so to justify their implementation. In addition, the taxonomy can also assist researchers in further developing the domain. By identifying common functionality, it could also help Information Technology (IT) teams in building and maintaining smart mobility services. Finally, we further discuss usage scenarios of the taxonomy by policy makers, IT staff and researchers.

Abstract
D-down arrow is a new dynamic logic combining regular modalities with the binder constructor typical of hybrid logic, which provides a smooth framework for the stepwise development of reactive systems. Actually, the logic is able to capture system properties at different levels of abstraction, from high-level safety and liveness requirements, to constructive specifications representing concrete processes. The paper discusses its semantics, given in terms of reachable transition systems with initial states, its expressive power and a proof system. The methodological framework is in debt to the landmark work of D. Sannella and A. Tarlecki, instantiating the generic concepts of constructor and abstractor implementations by standard operators on reactive components, e.g. relabelling and parallel composition, as constructors, and bisimulation for abstraction.

Abstract
This 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. © Springer International Publishing AG 2018.

Abstract
We study hybrid automata from a coalgebraic point of view. We show that such a perspective supports a generic theory of hybrid automata with a rich palette of definitions and results. This includes, among other things, notions of bisimulation and behaviour, state minimisation techniques, and regular expression languages.

Abstract
Regulations, laws, norms, and other documents of legal nature are a relevant part of any governmental organisation. During digitisation and transformation stages towards a digital government model, information and communication technologies are explored to improve internal processes and working practices of government infrastructures. This paper introduces preliminary results on a research line devoted to developing visualisation techniques for enhancing the readability and comprehension of legal texts. The content of documents is conveyed to a well-defined model, which is enriched with semantic information extracted automatically. Then, a set of digital views are created for document exploration from both a structural and semantic point of view. Effective and easier to use digital interfaces can enable and promote citizens engagement in decision-making processes, provide information for the public, and also enhance the study and analysis of legal texts by lawmakers, legal practitioners, and assorted scholars. © 2018 Copyright is held by the owner/author(s). Publication rights licensed to ACM.