Recent Publications

Santiago RHN, Bedregal B{\'ı}nRC, Madeira A, Martins MA.  2016.  On Interval Dynamic Logic. Formal Methods: Foundations and Applications - 19th Brazilian Symposium, {SBMF} 2016, Natal, Brazil, November 23-25, 2016, Proceedings. :129–144. Abstract
Madeira A, Martins MA, Barbosa LS.  2016.  A logic for n-dimensional hierarchical refinement. Proceedings 17th International Workshop on Refinement, Refine@FM 2015, Oslo, Norway, 22nd June 2015. 209:40–56.2.pdf
Madeira A, Barbosa LS, Hennicker R, Martins MA.  2016.  Dynamic Logic with Binders and Its Application to the Development of Reactive Systems. Theoretical Aspects of Computing - ICTAC 2016 - 13th International Colloquium, Taipei, Taiwan, ROC, October 24-31, 2016, Proceedings. 9965:422–440. Abstractmbhm16.pdf

This paper introduces a logic to support the specification and development of reactive systems on various levels of abstraction, from property specifications, concerning e.g. safety and liveness requirements, to constructive specifications representing concrete processes. This is achieved by combining binders of hybrid logic with regular modalities of dynamic logics in the same formalism, which we call D↓-logic. The semantics of our logic focuses on effective processes and is therefore given in terms of reachable transition systems with initial states. The second part of the paper resorts to this logic to frame stepwise development of reactive systems within the software development methodology proposed by Sannella and Tarlecki. In particular, we instantiate the generic concepts of constructor and abstractor implementations by using standard operators on reactive components, like relabelling and parallel composition, as constructors, and bisimulation for abstraction. We also study vertical composition of implementations which relies on the preservation of bisimularity by the constructions on labeleld transition systems.

Neves R, Barbosa LS.  2016.  Hybrid Automata as Coalgebras. Theoretical Aspects of Computing - ICTAC 2016 - 13th International Colloquium, Taipei, Taiwan, ROC, October 24-31, 2016, Proceedings. 9965:385–402. Abstractnb16.pdf

Able to simultaneously encode discrete transitions and continuous behaviour, hybrid automata are the de facto framework for the formal specification and analysis of hybrid systems. The current paper revisits hybrid automata from a coalgebraic point of view. This allows to interpret them as state-based components, and provides a uniform theory to address variability in their definition, as well as the corresponding notions of behaviour, bisimulation, and observational semantics.

Fernandes S, Barbosa LS.  2016.  Applying the 3C Model to FLOSS Communities. Collaboration and Technology - 22nd International Conference, CRIWG 2016, Kanazawa, Japan, September 14-16, 2016, Proceedings. 9848:139–150. Abstractfb16a.pdf

How learning occurs within Free/Libre Open Source (FLOSS) communities and what is the dynamics such projects (e.g. the life cycle of such projects) are very relevant questions when considering the use of FLOSS projects in a formal education setting. This paper introduces an approach based on the 3C collaboration model (communication, coordination and cooperation) to represent the collaborative learning dynamics within FLOSS communities. To explore the collaborative learning potential of FLOSS communities a number of questionnaires and interviews to selected FLOSS contributors were run. From this study a 3C collaborative model applicable to FLOSS communities was designed and discussed.

Fernandes S, Barbosa LS.  2016.  Electronic governance in Portugal: a silent pioneer. Proceedings of the International Conference on Electronic Governance and Open Society - Challenges in Eurasia, {EGOSE} 2016, St. Petersburg, Russia, November 22-23, 2016. :77–82. Abstractfb2016b.pdf

This paper sums up the Portuguese experience on launching and implementing a number of successful EGOV policies at different levels. Such a success was based on a holistic understanding of EGOV, in the confluence of technology, administrative reform and innovation processes, and enforced through a number of well-defined, consistent policies carried out over time. The role of national agencies, independent from local political instances and private interests, in the implementation of an effective EGOV strategy is also stressed.

Veiga L, Janowski T, Barbosa LS.  2016.  Digital Government and Administrative Burden Reduction. Proceedings of the 9th International Conference on Theory and Practice of Electronic Governance, ICEGOV 2016, Montevideo, Uruguay, March 1-3, 2016. :323–326. Abstractvjb16.pdf

Administrative burden represents the costs to businesses, citizens and the administration itself of complying with government regulations and procedures. The burden tends to increase with new forms of public governance that rely less on direct decisions and actions undertaken by traditional government bureaucracies, and more on government creating and regulating the environment for other, non-state actors to jointly address public needs. Based on the reviews of research and policy literature, this paper explores administrative burden as a policy problem, presents how Digital Government (DG) could be applied to address this problem, and identifies societal adoption, organizational readiness and other conditions under which DG can be an effective tool for Administrative Burden Reduction (ABR). Finally, the paper tracks ABR to the latest Contextualization stage in the DG evolution, and discusses possible development approaches and technological potential of pursuing ABR through DG.

Oliveira N, Barbosa LS.  2016.  An Enhanced Model for Stochastic Coordination. Proceedings of the First International Workshop on Formal Methods for and on the Cloud, iFMCloud@IFM 2016, Reykjavik, Iceland, 4th June 2016.. 228:35–45. Abstractob16.pdf

Applications developed over the cloud coordinate several, often anonymous, computational resources, distributed over different execution nodes, within flexible architectures. Coordination models able to represent quantitative data provide a powerful basis for their analysis and validation. This paper extends IMCreo, a semantic model for Stochastic reo based on interactive Markov chains, to enhance its scalability, by regarding each channel and node, as well as interface components, as independent stochastic processes that may (or may not) synchronise with the rest of the coordination circuit.

Silva JMC, Carvalho P, Bispo KA, Lima SR.  2016.  Lightweight Multivariate Sensing in WSNs. Ubiquitous Computing and Ambient Intelligence: 10th International Conference, UCAmI 2016, San Bartolomé de Tirajana, Gran Canaria, Spain, November 29 – December 2, 2016, Part II. :205–211. Abstract


Pereira R, Couto M, Saraiva J, Cunha J, Fernandes JP.  2016.  The Influence of the Java Collection Framework on Overall Energy Consumption. Proceedings of the 5th International Workshop on Green and Sustainable Software. :15–21. Abstract
Pereira R, Saraiva J, Cunha J, Fernandes JP.  2016.  User-friendly Spreadsheet Querying: An Empirical Study. Proceedings of the 31st Annual ACM Symposium on Applied Computing. :202–204. Abstract
Pontes R, Maia F, Paulo J, Vilaça RMP.  2016.  SafeRegions: Performance Evaluation of Multi-party Protocols on HBase. 35th {IEEE} Symposium on Reliable Distributed Systems Workshops, {SRDS} 2016 Workshop, Budapest, Hungary, September 26, 2016. :31–36. Abstract
Burihabwa D, Pontes R, Felber P, Maia F, Mercier H, Oliveira R, Paulo J, Schiavoni V.  2016.  On the Cost of Safe Storage for Public Clouds: An Experimental Evaluation. 35th {IEEE} Symposium on Reliable Distributed Systems, {SRDS} 2016, Budapest, Hungary, September 26-29, 2016. :157–166. Abstract
Couto R, Ribeiro AN, Campos JC.  2016.  Validating an Approach to Formalize Use Cases with Ontologies. Proceedings of the 13th International Workshop on Formal Engineering Approaches to Software Components and Architectures, FESCA@ETAPS 2016, Eindhoven, The Netherlands, 3rd April 2016.. :1–15. Abstract1603.08632.pdf


Santo JE, Frade MJ, Pinto L.  2016.  Permutability in Proof Terms for Intuitionistic Sequent Calculus with Cuts. 22nd International Conference on Types for Proofs and Programs, {TYPES} 2016, May 23-26, 2016, Novi Sad, Serbia. 97:10:1–10:27. Abstractlipics-types-2016-10thepublishedversion.pdf

This paper gives a comprehensive and coherent view on permutability in the intuitionistic sequent calculus with cuts. Specifically we show that, once permutability is packaged into appropriate global reduction procedures, it organizes the internal structure of the system and determines fragments with computational interest, both for the computation-as-proof-normalization and the computation-as-proof-search paradigms. The vehicle of the study is a λ-calculus of multiary proof terms with generalized application, previously developed by the authors (the paper argues this system represents the simplest fragment of ordinary sequent calculus that does not fall into mere natural deduction). We start by adapting to our setting the concept of normal proof, developed by Mints, Dyckhoff, and Pinto, and by defining natural proofs, so that a proof is normal iff it is natural and cut-free. Natural proofs form a subsystem with a transparent Curry- Howard interpretation (a kind of formal vector notation for λ-terms with vectors consisting of lists of lists of arguments), while searching for normal proofs corresponds to a slight relaxation of focusing (in the sense of LJT). Next, we define a process of permutative conversion to natural form, and show that its combination with cut elimination gives a concept of normalization for the sequent calculus. We derive a systematic picture of the full system comprehending a rich set of reduction procedures (cut elimination, flattening, permutative conversion, normalization, focalization), organizing the relevant subsystems and the important subclasses of cut-free, normal, and focused proofs.