1,721,000 research outputs found
Supervisory control of business processes with resources, parallel and mutually exclusive branches, loops, and uncertainty
No full textA recent direction in Business Process Management studied methodologies to control the execution of Business Processes under several sources of uncertainty in order to always get to the end by satisfying all constraints. Current approaches encode business processes into temporal constraint networks or timed game automata in order to exploit their related strategy synthesis algorithms. However, the proposed encodings can only synthesize single-strategies and fail to handle loops. To overcome these limits we propose an approach based on supervisory control. We consider structured business processes with resources, parallel and mutually exclusive branches, loops, and uncertainty. We provide an encoding into finite state automata and prove that their concurrent behavior models exactly all possible executions of the process. After that, we introduce tentative commitment constraints as a new class of constraints restricting the executions of a process. We define a tree decomposition of the process that plays a central role in modular supervisory control, and we prove that this modular approach is equivalent to the monolithic one. We provide an algorithm to compute the finest tree decomposition to reduce the computational effort of synthesizing supervisors
Model Checking of Optimal LTL and ASAP Properties
No full textModel checking has long been employed as a method for the formal verification of control systems, with a focus on ensuring correctness and safety. However, in practical scenarios (e.g., robotics, aviation and aerospace), simply verifying whether a control system satisfies a given property may not suffice. There is often the requisite to optimize system behavior with respect to certain criteria, such as response time. For instance, in verifying a reachability property, one may be interested in knowing if the controller reaches the goal as soon as possible (ASAP). Despite the simplicity of such requirement, its formalization has not yet been addressed in the literature and requires to reason about the strategy of the controller and the cost of the executions in closed-loop with the given environment. More in general, this paper proposes the formalization and verification of properties for controllers that must satisfy a temporal logic specification optimally, i.e., in the best way possible given the behavior on the plant to be controlled. This relies on and is parametrized by a quantitative semantics for temporal logic. We focus on linear-time temporal logic (LTL), for which various quantitative semantics have been defined. In order to characterize the fulfillment of LTL properties as soon as possible (ASAP), we introduce a new quantitative semantics related to the length of the shortest informative prefix. Finally, we focus on ASAP co-safety properties and reduce the optimal model checking to standard qualitative reactive synthesis. We provide a proof of concept demonstration of the reduction with nuXmv
Reactivity of [Re(eta2-H2)(CO)2P3]+ cations with alkynes: preparation of vinylidene and propadienylidene complexes
No full text
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Automating Numerical Parameters Along the Evolution of a Nonlinear System
No full textWhen analysing cyber-physical systems for runtime verification purposes, reachability analysis can be used to identify whether the set of reached points stays within given safe bounds. If the system dynamics exhibits nonlinearity, approximate numerical techniques (with rigorous numerics) are often necessary when dealing with system evolution. Since the error involved in numerical approximation should be kept low to perform verification successfully, the associated processing and memory costs become relevant especially when runtime verification is considered. Given a reachability analysis tool, the issue of controlling its numerical accuracy is not trivial from the user’s perspective, due to the complex interaction between the configuration parameters of the tool. As a result, user intervention in the tuning of a specific problem is always required. This paper explores the problem of automatically choosing numerical parameters that drive the computation of the finite-time reachable set, when the configuration parameters of the tool are specified within bounds or lists of values. In particular, it is designed to be performed along evolution, in order to adapt to local properties of the dynamics and to reduce the setup overhead, essential for runtime verification
The light side of interval temporal logic: The Bernays-Schönfinkel fragment of CDT
No full textDecidability and complexity of the satisfiability problem for the logics of time intervals have been extensively studied in the recent years. Even though most interval logics turn out to be undecidable, meaningful exceptions exist, such as the logics of temporal neighborhood and (some of) the logics of the subinterval relation. In this paper, we explore a different path to decidability: instead of restricting the set of modalities or imposing severe semantic restrictions, we take the most expressive interval temporal logic studied so far, namely, Venema's CDT, and we suitably limit the negation depth of modalities. The decidability of the satisfiability problem for the resulting fragment, called CDT_BS, over the class of all linear orders, is proved by embedding it into a well-known decidable quantifier prefix class of first-order logic, namely, Bernays-Schönfinkel class. In addition, we show that CDT_BS is in fact NP-complete (Bernays-Schönfinkel class is NEXPTIME-complete), and we prove its expressive completeness with respect to a suitable fragment of Bernays-Schönfinkel class. Finally, we show that any increase in the negation depth of CDT_BS modalities immediately yields undecidability
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Full text linkWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
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