Proof theory for hybrid(ised) logics

Hybridisation is a systematic process along which the characteristic features of hybrid logic, both at the syntactic and the semantic levels, are developed on top of an arbitrary logic framed as an institution. In a series of papers this process has been detailed and taken as a basis for a specification methodology for reconfigurable systems. The present paper extends this work by showing how a proof calculus (in both a Hilbert and a tableau based format) for the hybridised version of a logic can be systematically generated from a proof calculus for the latter. Such developments provide the basis for a complete proof theory for hybrid(ised) logics, and thus pave the way to the development of (dedicated) proof support.The authors are grateful to Torben Bräuner for helpful, inspiring discussions, and to the anonymous referees for their detailed comments. This work is funded by ERDF—European Regional Development Fund, through the COMPETE Programme, and by National Funds through Fundação para a Ciência e a Tecnologia(FCT) within project PTDC/EEI-CTP/4836/2014. Moreover, the first and the second authors are sponsored by FCT grants SFRH/BD/52234/2013 and SFRH/BPD/103004/2014, respectively. M. Mar-tins is also supported by the EU FP7 Marie Curie PIRSES-GA-2012-318986 project GeTFun: Generalizing Truth-Functionality and FCT project UID/MAT/04106/2013 through CIDMA. L.Barbosa is further supported by FCT in the context of SFRH/B-SAB/113890/2015

A Logic for robotics?

This paper introduces HHL, a hierarchical variant of hybrid logic. First-order correspondence and a Hennessy-Milner like theorem relating (hierarchical) bisimulation and logical equivalence for HHLare presented. Combining hierarchical transition structures with the ability to refer to specific states at any level of description, this logic seems suitable to express and verify properties of hierarchical transition systems, a pervasive semantic structure in Computer Science.Dynamic logic combines logic with programs, which at a certain level of abstraction, can be regarded as behaviours changing the system state and, therefore, the truth value of formulas. This paper suggests a method for generating such logics for the domain of robot controllers and illustrates it with a logic for handling resource consumption

Introducing hierarquical hybrid logic

This paper introduces HHL, a hierarchical variant of hybrid logic. First-order correspondence and a Hennessy-Milner like theorem relating (hierarchical) bisimulation and logical equivalence for HHL are presented. Combining hierarchical transition structures with the ability to refer to specific states at any level of description, this logic seems suitable to express and verify properties of hierarchical transition systems, a pervasive semantic structure in Computer Science

An institution for Alloy and its translation to second-order logic

Publicado em "Integration of reusable systems". ISBN 978-3-319-04716-4Lightweight formal methods, of which Alloy is a prime example, combine the rigour of mathematics without compromising simplicity of use and suitable tool support. In some cases, however, the verification of safety or mission critical software entails the need for more sophisticated technologies, typically based on theorem provers. This explains a number of attempts to connect Alloy to specific theorem provers documented in the literature. This chapter, however, takes a different perspective: instead of focusing on one more combination of Alloy with still another prover, it lays out the foundations to fully integrate this system in the Hets platform which supports a huge network of logics, logic translators and provers. This makes possible for Alloy specifications to “borrow” the power of several, non dedicated proof systems. The chapter extends the authors’ previous work on this subject by developing in full detail the semantical foundations for this integration, including a formalisation of Alloy as an institution, and introducing a new, more general translation of the latter to second-order logic.(undefined

Giving ALLOY a family

Lightweight formal methods ought to provide to the end user the rigorousness of mathematics, without compromising simplicity and intuitiveness. ALLOY is a powerful tool, particularly successful on this mission. Limitations on the verification side, however, are known to prevent its wider use in the development of safety or mission critical applications. A number of researchers proposed ways to connect Alloy to other tools in order to meet such challenges. This paper’s proposal, however, is not establishing a link from ALLOY to another single tool, but rather to “plunge” it into the HETS network of logics, logic translators and provers. This makes possible for Alloy specifications to “borrow” the power of several, non dedicated proof systems. Semantical foundations for this integration are discussed in detail.FC

When even the interface evolves ...

This paper extends the authors’ previous work on a formal approach to the specification of reconfigurable systems in which configurations are taken as local states in a suitable transition structure. The novelty is the explicit consideration that not only the realisation of a service may change from a configuration to another, but also the set of services provided and even their functionality, may themselves vary. In other words, interfaces may evolve, as well.FC

Littré’s hernia – a case of a Meckel’s diverticulum in a strangulated femoral hernia and literature review

Introdução: O divertículo de Meckel é a anomalia gastrointestinal congénita mais comum e resulta da obliteração incompleta do ducto vitelino. A hérnia de Littré define-se pela presença de um divertículo de Meckel no saco herniário. O estrangulamento do divertículo de Meckel numa hérnia femoral é uma entidade extremamente rara que requer correção cirúrgica imediata. Caso Clínico: Reportamos o caso clínico de uma mulher de 18 anos que recorreu ao serviço de urgência por uma hérnia femoral dolorosa e encarcerada à esquerda, sem sinais ou sintomas de obstrução intestinal associados. Durante a intervenção cirúrgica, aquando da abertura do saco herniário, foi identificado um divertículo de Meckel, procedendo-se então a diverticulectomia. A ansa de intestino delgado não se encontrava herniada nem tinha sinais de isquemia, pelo que não foi necessário realizar uma enterectomia. O defeito herniário foi subsequentemente corrigido através da técnica de Lichtenstein modificada. Discussão: A sintomatologia de um divertículo de Meckel complicado é inespecífica e dependente do tipo de complicação. O diagnóstico de hérnia de Littré é exigente e difícil de estabelecer durante o pré-operatório, uma vez que a sua apresentação clínica é ambígua e a imagiologia tem um papel limitado. Quando a obstrução do intestino delgado é provocada por um divertículo de Meckel complicado, a intervenção cirúrgica tem como objetivo principal remover o divertículo e corrigir a patologia associada, independentemente da abordagem utilizada ser laparoscópica ou cirurgia aberta. Conclusão: No caso de uma hérnia de Littré estrangulada o tratamento é baseado na condição clínica do doente e na experiência do cirurgião. Não obstante, o tratamento requer, pelo menos, uma ressecção completa do divertículo para evitar complicações futuras.Introduction: Meckel’s diverticulum is the most common gastrointestinal congenital anomaly and it results from an incomplete obliteration of the vitelline duct. Littré’s hernia is defined by the presence of a Meckel’s diverticulum in a hernia sac. A strangulated Meckel’s diverticulum in a femoral hernia is an extremely rare entity and its management requires prompt surgery. Case Report: We describe a case of a 18-year-old woman that presented with a painful incarcerated femoral hernia in her left groin. She did not have any signs or symptoms of bowel obstruction. During surgery, a Meckel’s diverticulum was identified in the hernia sac. The  small bowel was not herniated and did not show signs of ischaemia, thus, an enterectomy was not required. A diverticulectomy was performed and the hernia defect was subsequently repaired with a modified Lichtenstein technique. Discussion: The symptomatology of a complicated Meckel’s diverticulum is non-specific and dependent on the type of complication. The diagnosis of Littré’s hernia is challenging and difficult to establish preoperatively since its presentation is ambiguous and imaging has a limited role. When small bowel obstruction is caused by a complicated Meckel’s diverticulum, the main aim of surgery is to remove the diverticulum and to correct the associated pathology, either by laparoscopy or by an open surgical approach. Conclusion: A patient’s condition and surgeon based management is generally adopted in case of a strangulated Littré’s hernia. Nevertheless, it requires complete resection of the diverticulum to avoid future complications

Joint Carrier-Phase Estimation for Digital Subcarrier Multiplexing Systems With Symbol-Rate Optimization

Digital subcarrier multiplexing (SCM) has recently emerged as a promising solution for next-generation ultra-high-baudrate coherent optical communication systems. Among its distinctive advantages over traditional single-carrier modulation, SCM enables the exploitation of symbol-rate optimization (SRO), which has been shown to enable the passive mitigation of the nonlinear interference noise (NLIN) that is generated during propagation over dispersion-unmanaged optical fiber systems. However, the full exploitation of SRO-based NLIN mitigation is severely hindered by the uncompensated distortion caused by laser phase noise (LPN) and non-linear phase noise (NLPN), whose impact is magnified by the use of low-baudrate subcarriers. Resorting to low-complexity carrier phase estimation (CPE) algorithms, in this paper we experimentally demonstrate that it is possible to overcome the hurdles posed by LPN and NLPN in SCM systems, provided that adequate joint-subcarrier CPE processing is employed. A dual-stage joint-processing approach composed of a pilot-based CPE optionally followed by a blind phase search (BPS)-based estimator is implemented and experimentally assessed, enabling to effectively optimize the symbol-rate per subcarrier down to 3 GBaud, in accordance with the theoretical SRO predictions for the system under test. In addition, we demonstrate that signal-to-noise ratio (SNR) gains of more than 1 dB can be achieved through joint-subcarrier CPE processing in shorter-reach links, while this gain tends to progressively reduce with increasing propagation distance, down to about 0.5 dB gain after 3000 km propagation

A method for rigorous design of reconfigurable systems

Reconfigurability, understood as the ability of a system to behave differently in different modes of operation and commute between them along its lifetime, is a cross-cutting concern in modern Software Engineering. This paper introduces a specification method for reconfigurable software based on a global transition structure to capture the system's reconfiguration space, and a local specification of each operation mode in whatever logic (equational, first-order, partial, fuzzy, probabilistic, etc.) is found expressive enough for handling its requirements. In the method these two levels are not only made explicit and juxtaposed, but formally interrelated. The key to achieve such a goal is a systematic process of hybridisation of logics through which the relationship between the local and global levels of a specification becomes internalised in the logic itself.This work is financed by the ERDF – European Regional Development Fund through the Operational Programme for Competitiveness and Internationalisation – COMPETE 2020 Programme and by National Funds through the Portuguese funding agency, FCT – Fundação para a Ciência e a Tecnologia within projects POCI-01-0145-FEDER-016692 and UID/MAT/04106/2013. The first author is further supported by the BPD FCT Grant SFRH/BPD/103004/2014, and R. Neves is sponsored by FCT Grant SFRH/BD/52234/2013. M.A. Martins is also funded by the EU FP7 Marie Curie PIRSESGA-2012-318986 project GeTFun: Generalizing Truth-Functionality