The Spectrum of Strong Behavioral Equivalences for Nondeterministic and Probabilistic Processes

We present a spectrum of trace-based, testing, and bisimulation equivalences for nondeterministic and probabilistic processes whose activities are all observable. For every equivalence under study, we examine the discriminating power of three variants stemming from three approaches that differ for the way probabilities of events are compared when nondeterministic choices are resolved via deterministic schedulers. We show that the first approach - which compares two resolutions relatively to the probability distributions of all considered events - results in a fragment of the spectrum compatible with the spectrum of behavioral equivalences for fully probabilistic processes. In contrast, the second approach - which compares the probabilities of the events of a resolution with the probabilities of the same events in possibly different resolutions - gives rise to another fragment composed of coarser equivalences that exhibits several analogies with the spectrum of behavioral equivalences for fully nondeterministic processes. Finally, the third approach - which only compares the extremal probabilities of each event stemming from the different resolutions - yields even coarser equivalences that, however, give rise to a hierarchy similar to that stemming from the second approach.Comment: In Proceedings QAPL 2013, arXiv:1306.241

Uniform Labeled Transition Systems for Nondeterministic, Probabilistic, and Stochastic Process Calculi

Labeled transition systems are typically used to represent the behavior of nondeterministic processes, with labeled transitions defining a one-step state to-state reachability relation. This model has been recently made more general by modifying the transition relation in such a way that it associates with any source state and transition label a reachability distribution, i.e., a function mapping each possible target state to a value of some domain that expresses the degree of one-step reachability of that target state. In this extended abstract, we show how the resulting model, called ULTraS from Uniform Labeled Transition System, can be naturally used to give semantics to a fully nondeterministic, a fully probabilistic, and a fully stochastic variant of a CSP-like process language.Comment: In Proceedings PACO 2011, arXiv:1108.145

A uniform framework for modelling nondeterministic, probabilistic, stochastic, or mixed processes and their behavioral equivalences

Labeled transition systems are typically used as behavioral models of concurrent processes, and the labeled transitions define the a one-step state-to-state reachability relation. This model can be made generalized by modifying the transition relation to associate a state reachability distribution, rather than a single target state, with any pair of source state and transition label. The state reachability distribution becomes a function mapping each possible target state to a value that expresses the degree of one-step reachability of that state. Values are taken from a preordered set equipped with a minimum that denotes unreachability. By selecting suitable preordered sets, the resulting model, called ULTraS from Uniform Labeled Transition System, can be specialized to capture well-known models of fully nondeterministic processes (LTS), fully probabilistic processes (ADTMC), fully stochastic processes (ACTMC), and of nondeterministic and probabilistic (MDP) or nondeterministic and stochastic (CTMDP) processes. This uniform treatment of different behavioral models extends to behavioral equivalences. These can be defined on ULTraS by relying on appropriate measure functions that expresses the degree of reachability of a set of states when performing single-step or multi-step computations. It is shown that the specializations of bisimulation, trace, and testing equivalences for the different classes of ULTraS coincide with the behavioral equivalences defined in the literature over traditional models

Revisiting bisimilarity and its modal logic for nondeterministic and probabilistic processes

We consider PML, the probabilistic version of Hennessy-Milner logic introduced by Larsen and Skou to characterize bisimilarity over probabilistic processes without internal nondeterminism.We provide two different interpretations for PML by considering nondeterministic and probabilistic processes as models, and we exhibit two new bisimulation-based equivalences that are in full agreement with those interpretations. Our new equivalences include as coarsest congruences the two bisimilarities for nondeterministic and probabilistic processes proposed by Segala and Lynch. The latter equivalences are instead in agreement with two versions of Hennessy-Milner logic extended with an additional probabilistic operator interpreted over state distributions rather than over individual states. Thus, our new interpretations of PML and the corresponding new bisimilarities offer a uniform framework for reasoning on processes that are purely nondeterministic or reactive probabilistic or are mixing nondeterminism and probability in an alternating/non-alternating way

El horror de la locura en Estrella distante y Nocturno de Chile

The article examines the thematic dimension of madness present in the novels Estrella distante and Nocturno de Chile by Roberto Bolaño in order to determine the various ways by which the narrator subjectivity develops a critical consciousness of madness from the traumatic experience of the Chilean dictatorship. Also, this dimension evidences the articulation of a language of madness as literary aesthetics of artistic experience of limits: the horror. Accordingly, a preliminary analysis of contemporary history as a meeting place between violent media versus artistic media that account for the chiaroscuro of Latin American modernity is offered.El artículo estudia la dimensión mimética de la locura presente en las novelas Estrella distante y Nocturno de Chile de Roberto Bolaño con el fin de determinar los diversos modos mediante los cuales la subjetividad narrativa desarrolla una conciencia crítica de la locura a partir de la experiencia traumática de la dictadura chilena. Asimismo, esta dimensión evidencia la articulación de un lenguaje de la locura como estética literaria de la experiencia artística de los límites: el horror. En consecuencia, se ofrece un análisis preliminar sobre la historia contemporánea como espacio de encuentro entre los medios violentos versus los medios artísticos que dan cuenta de los claroscuros de la modernidad latinoamericana

Estrategias discursivas en Lo insondable de Federico Zurita Hecht

At first glance, the novel Lo insondable (2015) by the Chilean writer Federico Zurita Hecht presents a set of autonomous stories that would contribute to the resolution of its enigmatic central argument: the imminent destruction of the universe by activating a machine that would dissolve the contradictions of neoliberal capitalist logic in Latin America. Although the division of the different plots is reinforced by the deployment of multiple narrators and discursive strategies, the novel however, accounts for an interconnected universe that would allow to decipher the current ramifications of the historical dynamics derived from the Cold War and that it would promote a revolution in Latin America.A simple vista, la novela Lo insondable (2015) del escritor chileno Federico Zurita Hecht presenta un conjunto de relatos autónomos que contribuirían a la resolución de su enigmático argumento central: la inminente destrucción del universo mediante la activación de una máquina que disolvería las contradicciones de la lógica capitalista neoliberal en Latinoamérica. Si bien el fraccionamiento de las distintas tramas es reforzado por el despliegue de múltiples narradores y estrategias discursivas, la novela da cuenta no obstante, de un universo interconectado que permitiría descifrar las ramificaciones actuales de la dinámica histórica derivada de la Guerra Fría y que impulsaría una revolución en Latinoamérica

Theoretical Comparison between a Traditional Anaerobic Digestion and an Innovative One

The paper, after analyzing the technical characteristics of anaerobic digestion traditional plants of zootechnical effluents, identifies those relating to an innovative system, which divides the evolutionary stages of biodegradation of the material in hydrogenesis aerobic, hydrogenesis anaerobic, acidogenesis-acetogenesis and methanogenesis. The theoretical treatment will have to find validation in the pilot plant which will be building and from which it will be possible to determine additional technical, economic, and environmental indications

Revisiting bisimilarity and its modal logic for nondeterministic and probabilistic processes

The logic PML is a probabilistic version of Hennessy–Milner logic introduced by Larsen and Skou to characterize bisimilarity over probabilistic processes without internal nondeterminism. In this paper, two alternative interpretations of PML over nondeterministic and probabilistic processes as models are considered, and two new bisimulation-based equivalences that are in full agreement with those interpretations are provided. The new equivalences include as coarsest congruences the two bisimilarities for nondeterministic and probabilistic processes proposed by Segala and Lynch. The latter equivalences are instead known to agree with two versions of Hennessy–Milner logic extended with an additional probabilistic operator interpreted over state distributions in place of individual states. The new interpretations of PML and the corresponding new bisimilarities are thus the first ones to offer a uniform framework for reasoning on processes that are purely nondeterministic or reactive probabilistic or that mix nondeterminism and probability in an alternating/nonalternating way