11,547 research outputs found
Application of Decomposition and Generic Instantiation
It is believed that reusability in formal development should reduce the time and cost of formal modelling within a production environment. Event-B is a formal method that allows modelling and refinement of systems. Generic instantiation and decomposition are techniques that simplify formal developments by reusing existing models and avoiding re-proofs. We apply these techniques in Event-B for the development of a metro system case study based on safety properties. This work aims to be give some guidelines of a practical way to develop large systems by instantiation of generic models and (shared event) decompose components into smaller sub-components
Event-B model decomposition
Two methods have been identified in the DEPLOY project for Event-B model decomposition: the shared variable decomposition (called A-style decomposition), and the shared event decomposition (or B-style decomposition). Both allow the decomposition of a (concrete) model into several independent sub-models which may then be refined separately. The purpose of this paper is to introduce the Event-B model decomposition, from theory (A-style vs. B-style, differences and similarities) to practice (decomposition plug-in of the Rodin [1] platform)
Shared Event Composition/Decomposition in Event-B
The construction of specifications is often a combination of smaller sub-components. Composition and decomposition are techniques that support reuse and allow us to formally combine sub-components through refinement steps while reusing their properties. Sub-components can result from a design or architectural goal and a refinement framework should allow further parallel development over the sub-components. We propose the definition of composition and decomposition in the Event-B formalism following a shared event approach where sub-components interact via synchronisation over shared events and shared states are not allow. We define the necessary proof obligations to ensure a valid composition or decomposition. We also show that shared event composition preserves refinement proofs for sub-components, that is, in order to maintain refinement of compositions, it is sufficient to prove refinement between corresponding subcomponents. A case study applying these two techniques is illustrated using Rodin, the Event-B toolset
Hybrid Petri net model of a traffic intersection in an urban network
Control in urban traffic networks constitutes an important and challenging research topic nowadays. In the literature, a lot of work can be found devoted to improving the performance of the traffic flow in such systems, by means of controlling the red-to-green switching times of traffic signals. Different techniques have been proposed and commercially implemented, ranging from heuristic methods to model-based optimization. However, given the complexity of the dynamics and the scale of urban traffic networks, there is still a lot of scope for improvement. In this work, a new hybrid model for the traffic behavior at an intersection is introduced. It captures important aspects of the flow dynamics in urban networks. It is shown how this model can be used in order to obtain control strategies that improve the flow of traffic at intersections, leading to the future possibility of controlling several connected intersections in a distributed way
Messianisme et image dialectique au cinéma
[RĂ©sumĂ©] Messianisme et Image Dialectique au CinĂ©ma Le caractĂšre Ă©minemment historique de lâimage, oĂč lâexpĂ©rience historique se fait par des images qui sont Ă son tour chargĂ©es dâhistoire nous amĂšne Ă une vision messianique de lâimage cinĂ©matographique de Guy Debord Ă Godard (Agamben, 1998). Ce cinĂ©ma sâoriente vers une rĂ©vĂ©lation finale quâest la RĂ©volution, la transformation sociale. Glauber Rocha autre cinĂ©aste de lâimage dialectique, partage Ă©galement cette perpective messianique, ses films sont rĂ©vĂšlateurs Ă la fois de lâoscillation entre le marxisme existentiel, le messianisme vĂ©cu et la perte de la vision rĂ©demptrice. On dĂ©veloppera autour de ce thĂ©me, Ă lâaide de la sĂ©miotique, quelques considĂ©rations sur la crĂ©ation des signes par le cinĂ©ma et Ă partir de la question de lâintelligibilitĂ© dialectique de lâhomme chez Sartre, pour que lâagir de lâhomme, sa praxis, sâinscrit dans un but, tenter ainsi de comprendre lâimage dialectique. DâaprĂšs Sartre, lâhomme est crĂ©ateur des signes quâon ne peut saisir quâĂ partir de la comprĂ©hension du « dĂ©passement », car toute action humaine est chargĂ©e et de prĂ©sent et dâavenir (Theodor Schwarz,1990). Quel est donc le statut de lâimage dans la crĂ©ation de ce dĂ©passement? Lâimage dialectique rend-il visible lâinvisible Salut RĂ©volutionaire? On mettra en examen le caractĂ©re messianique de lâimage cinematographiqu
Southwest airlines Co.: consistency for the future
This Work Project consists of an Equity Research report of Southwest Airlines Co., forecasting the future companyâs performance. Currently, the company is one of the market leaders and has a higher operating margin than the industry. However, the arising of low-cost and ultra-low-cost airlines will increase the industryâs price pressure. Moreover, the company will face operating costs management challenges in the future, mainly related to labor and fuel, which will affect its operating margin, enhancing the companyâs concerns regarding increasing operational measures. Hence, it was issued a âHoldâ recommendation, estimating a price target of $58.76, as of December 2020
âEvery human action is anthropophagicâ: Oswald's Cultural Anthropophagy and Theoretical Psychology
The Freudian theory and the era of acceleration announced by the Futurist Manifesto arrived in Brazil in 1899 and 1909, respectively. Afterwards the concrete reception of these two significant events became more than the symptomatic revelation of the shocks provoked by industrial modernity and its powerful undercurrent of anxieties. The poet, âclownâ, writer and major figure of the Brazilian modernist avant-garde, Oswald de Andrade (1890-1954) absorbed Freud and the Futurist Manifesto at once, re-pragmatized and re-semantized them. Oswald's concept of Cultural Anthropophagy (1928) as a central interpretative strategy, to be exact, an hermeneutic approach is defined by Haroldo de Campos aptly: âOswald's âAnthropophagyâ [...] is the thought of critical devoration of the universal cultural heritageâ (Campos,1986). The introduction of the anthropophagic trope inspired by Native Americansâ metaphysics leads the poet to a subversion of the Gestalt/Behavior psychological theories: âThe anthropophagic function of the psychological behavior is reduced to two parts: 1) totemiser the external taboos; 2) create a new taboo in exogamic functionâ (Andrade,1929). From 1928 to 1950 the Anthropophagy approach on the interaction between the individual and the environment gained philosophical consistency. Oswald's thesis is a conceptual alternative that attempted to bring answers through the amplification of our ethical becoming. As an epistemological perspective attentive to the different modes of existence, the proposition of Oswald is a field of transformative practices having the power to overcome the techno-industrial paradigms. I will examine the contribution of Oswald de Andrade to theoretical psychology and to the issues that arise in an âEra of Accelerationâ where the symbolic field is replaced by a cybernetic field
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