Causal Consistency for Reversible Multiparty Protocols

In programming models with a reversible semantics, computational steps can be undone. This paper addresses the integration of reversible semantics into process languages for communication-centric systems equipped with behavioral types. In prior work, we introduced a monitors-as-memories approach to seamlessly integrate reversible semantics into a process model in which concurrency is governed by session types (a class of behavioral types), covering binary (two-party) protocols with synchronous communication. The applicability and expressiveness of the binary setting, however, is limited. Here we extend our approach, and use it to define reversible semantics for an expressive process model that accounts for multiparty (n-party) protocols, asynchronous communication, decoupled rollbacks, and abstraction passing. As main result, we prove that our reversible semantics for multiparty protocols is causally-consistent. A key technical ingredient in our developments is an alternative reversible semantics with atomic rollbacks, which is conceptually simple and is shown to characterize decoupled rollbacks.Comment: Extended, revised version of a PPDP'17 paper (https://doi.org/10.1145/3131851.3131864

Cyberbullying, K-12 Public Schools, and the 1st Amendment

The first amendment protected students’ first amendment rights in K-12 public schools; however, state antibullying legislation required school officials to discipline students for bullying and, in most states, cyberbullying as well. An increasing number of students had access to mobile devices at home and during the school day. School officials had the responsibility to protect students from instances of bullying and cyberbullying; however, school officials did not fully understand the extent of their authority to discipline students for acts of bullying that occurred online, off school grounds. Despite the existence of state antibullying laws in all fifty states, contradictory appellate court decisions in cases involving cyberbullying and K-12 public schools made it difficult for school administrators to understand their authority. Appellate courts utilized a Tinker test when determining the outcomes of cases involving cyberbullying and K-12 public schools. The Tinker test was derived from the Supreme Court decision in Tinker vs. Des Moines Independent Community School District (1969), in which the Supreme Court overturned the suspension of students that wore armbands to protest the Vietnam War. There were two prongs of the Tinker test: (1) whether the instance of cyberbullying caused a substantial interference in the school, and (2) whether or not a substantial interference could be reasonably forecasted. The purpose of this public policy dissertation was to provide state legislators and school administrators with an in-depth review of state antibullying laws as well as greater insight into how the appellate courts interpreted the extent and limitations of First Amendment in K-12 public schools. This public policy dissertation compared state antibullying legislation in all 50 states in the United States and reviews all appellate court decisions involving K-12 public schools and cyberbullying. Each state’s legislation was reviewed between October 31, 2016, and December 31, 2016, to determine (1) if there was an antibullying law in effect, (2) if cyberbullying was included in the legislation, (3) if bullying was defined as a one-time event, (4) if school officials were given the authority to discipline students for off-campus behavior, (5) if schools were required to implement an antibullying policy, (6) if the substantial interference or substantial disruption language from Tinker was included in the antibullying legislation, (7) if there was a school sanction for bullying, (8) if there was a criminal sanction for face-to-face bullying, and (9) if there was a criminal sanction for cyberbullying. Each appellate court decision involving K-12 public schools and cyberbullying was reviewed to determine how the Tinker test was applied in each case

Wearable Platform for Automatic Recognition of Parkinson Disease by Muscular Implication Monitoring

The need for diagnostic tools for the characterization of progressive movement disorders - as the Parkinson Disease (PD) - aiming to early detect and monitor the pathology is getting more and more impelling. The parallel request of wearable and wireless solutions, for the real-time monitoring in a non-controlled environment, has led to the implementation of a Quantitative Gait Analysis platform for the extraction of muscular implications features in ordinary motor action, such as gait. The here proposed platform is used for the quantification of PD symptoms. Addressing the wearable trend, the proposed architecture is able to define the real-time modulation of the muscular indexes by using 8 EMG wireless nodes positioned on lower limbs. The implemented system “translates” the acquisition in a 1-bit signal, exploiting a dynamic thresholding algorithm. The resulting 1-bit signals are used both to define muscular indexes both to drastically reduce the amount of data to be analyzed, preserving at the same time the muscular information. The overall architecture has been fully implemented on Altera Cyclone V FPGA. The system has been tested on 4 subjects: 2 affected by PD and 2 healthy subjects (control group). The experimental results highlight the validity of the proposed solution in Disease recognition and the outcomes match the clinical literature results

Reversibility in session-based concurrency: A fresh look

Much research has studied foundations for correct and reliable communication-centric software systems. A salient approach to correctness uses verification based on session types to enforce structured communications; a recent approach to reliability uses reversible actions as a way of reacting to unanticipated events or failures. In this paper, we develop a simple observation: the semantic machinery required to define asynchronous (queue-based), monitored communications can also support reversible protocols. We propose a framework of session communication in which monitors support reversibility of (untyped) processes. Main novelty in our approach are session types with present and past, which allow us to streamline the semantics of reversible actions. We prove that reversibility in our framework is causally consistent, and define ways of using monitors to control reversible actions. Keyword

Bridging Causal Reversibility and Time Reversibility: A Stochastic Process Algebraic Approach

Causal reversibility blends reversibility and causality for concurrent systems. It indicates that an action can be undone provided that all of its consequences have been undone already, thus making it possible to bring the system back to a past consistent state. Time reversibility is instead considered in the field of stochastic processes, mostly for efficient analysis purposes. A performance model based on a continuous-time Markov chain is time reversible if its stochastic behavior remains the same when the direction of time is reversed. We bridge these two theories of reversibility by showing the conditions under which causal reversibility and time reversibility are both ensured by construction. This is done in the setting of a stochastic process calculus, which is then equipped with a variant of stochastic bisimilarity accounting for both forward and backward directions

Formulazione semplificata per il calcolo in forma chiusa del diagramma Momento-Curvatura di una sezione circolare cava in CA (in Italian)

Per un’analisi di vulnerabilità di un ponte a travata è possibile assumere che la curva di capacità della struttura sia approssimabile con la curva di capacità della pila critica. Il comportamento della pila critica può essere, in generale, influenzato da vari meccanismi quali la flessione, il taglio, gli effetti del second’ordine, lo sfilamento delle barre longitudinali o la loro instabilizzazione. Il comportamento flessionale è noto se si conosce il diagramma MomentoCurvatura della sezione d’incastro e la lunghezza di cerniera plastica. Considerando che gli altri meccanismi possono essere valutati con formulazioni approssimate l’aspetto chiave del problema è il diagramma MomentoCurvatura. Dopo aver valutato la sezione circolare piena in lavori precedenti, nella presente memoria si propone una procedura per valutare il diagramma Momento-Curvatura di una sezione circolare cava in C.A. definendo la posizione di alcuni suoi punti caratteristici. Per ognuno di questi si propone una soluzione adimensionale in forma chiusa che dipende da quattro parametri anch’essi adimensionali: rapporto tra raggio del foro e raggio esterno, rapporto di sforzo normale, rapporto meccanico di armatura longitudinale, rapporto volumetrico di staffatura. L’idea di base è quella di avere buone indicazioni sulle prestazioni dei materiali (snervamento, salto del copriferro, collasso, etc) basandosi su pochi parametri di input

Simplified closed-form solution for the determination of the moment-curvature response of a circular RC section

A seismic vulnerability analysis of a multi-span simply supported bridge is often based on the seismic response of the most critical pier. This response is influenced by different collapse modes (flexural, shear, second order effects, lap-splice of longitudinal bars or their buckling). Among these the flexural behaviour is important and it's known if the equivalent plastic hinge length and the Moment-Curvature law of the fixed end are given. This paper provides a closed-form dimensionless solution to obtain a 5 point Moment-Curvature diagram for circular RC section. The solution is based only on three parameters: dimensionless axial force, mechanical percentage of longitudinal reinforcement, geometrical percentage of transversal reinforcement. A numerical example is presented to test the solution comparing it with a FEM analysis

Multi-model assessment of the late-winter extra-tropical response to El Niño and La Nñna

El Ni˜no-Southern Oscillation (ENSO) is a natural phenomenon in the tropical Pacific and the dominant mode of climate variability on interannual timescales. The first term, El Ni˜no, refers to a recurring warming of the tropical Pacific Ocean (every 2-7 years), while the opposite phase, an anomalous cooling, is called La Ni˜na. These variations in sea surface temperature (SST) are accompanied by changes in the tropical atmospheric circulation (Southern Oscillation), thus making ENSO a coupled phenomenon involving ocean-atmosphere interactions. Furthermore, ENSO can affect climate in regions far from the tropical Pacific, producing a cascade of global impacts through so-called ‘teleconnections’. Understanding the extra-tropical impacts of ENSO is important to improve seasonal forecasts, for which it represents the most important source of predictability. In the North Atlantic-European (NAE) sector, the ENSO teleconnection is still controversial in several aspects. A first cornerstone was set in a review by Br¨onnimann (2007) [1], who concluded that a robust, ‘canonical’ ENSO signal exists over the NAE region in late winter (January to March, JFM): a dipole in sea-level pressure (SLP) with centers over the midlatitude and high-latitude North Atlantic. While Br¨onnimann described this pattern as “close to symmetric” for El Ni˜no and La Ni˜na, recent studies deliver contradictory results, with some reporting a symmetric signal (e.g. [2] [3] [4]) and others claiming asymmetry (e.g. [5] [6] [7]). The actual linearity of the ENSO-NAE teleconnection thus remains unresolved, and addressing this issue is the primary objective of this study. We will also investigate another key aspect of the ENSONAE teleconnection that is nothing but settled: the dynamical mechanism leading to the ‘canonical’ SLP dipole. The underlying idea of this study is to use idealized experiments with atmospheric models forced by symmetric anomalous SST patterns representing El Ni˜no and La Ni˜na to diagnose symmetries and asymmetries in the extra-tropical response. A multi-model approach is used, as the experiments analyzed here are run with the same protocol using three stateof- the-art models. We aim not only at diagnosing asymmetries in the extra-tropical ENSO-related SLP signal, but also at understanding their cause by examining all the steps involved in the atmospheric response, starting from the tropical Pacific