Automatically Deriving Schematic Theorems for Dynamic Contexts

International audienceHypothetical judgments go hand-in-hand with higher-order abstract syntax for meta-theoretic reasoning. Such judgments have two kinds of assumptions: those that are statically known from the specification, and the dynamic assumptions that result from building derivations out of the specification clauses. These dynamic assumptions often have a simple regular structure of repetitions of blocks of related assumptions, with each block generally involving one or several variables and their properties, that are added to the context in a single backchaining step. Reflecting on this regular structure can let us derive a number of structural properties about the elements of the context. We present an extension of the Abella theorem prover, which is based on a simply typed intuitionistic reasoning logic supporting (co-)inductive definitions and generic quantification. Dynamic contexts are repre-sented in Abella using lists of formulas for the assumptions and quantifier nesting for the variables, together with an inductively defined context relation that specifies their structure. We add a new mechanism for defining particular kinds of regular context relations, called schemas, and tacticals to derive theorems from these schemas as needed. Importantly, our extension leaves the trusted kernel of Abella unchanged. We show that these tacticals can eliminate many commonly encountered kinds of administrative lemmas that would otherwise have to be proven manually, which is a common source of complaints from Abella users

La notion de désir dans la philosophie de Gilles Deleuze

Mémoire numérisé par la Division de la gestion de documents et des archives de l'Université de Montréal

Pour une esthétique de la non-réconciliation Montage, histoire et politique dans le film Nicht Versöhnt de Jean- Marie Straub et Danièle Huillet

L’œuvre de Jean-Marie Straub et Danièle Huillet est souvent considérée comme l’une des plus radicales de l’histoire du cinéma européen. Nous avons tenté ici d’interroger le caractère politique de leur cinéma en nous concentrant sur leur premier film, Nicht Versöhnt Oder es hilft nur Gewalt wo Gewalt herrscht, qui présente ce que nous décrirons ici comme une esthétique de la non-réconciliation, une esthétique du cinéma qui s’émancipe des codes généralement utilisés par l’industrie pour tenter de se rapprocher d’une vision moins corrompue du réel. La forme de cinéma qui en résulte leur permet d’offrir un regard différent sur les lectures de l’histoire puisque ce film a d’abord été réalisé en réaction au fait que le peuple allemand prétendait être réconcilié avec son histoire. Nous montrerons que pour le couple de cinéastes, un cinéma réellement politique doit faire ressurgir les traces du passé réprimées sous la surface d’un présent lissé par les classes dirigeantes.The work of Jean-Marie Straub and Danièle Huillet is often considered one of the most radical in the history of European cinema. We have tried here to question the political character of their cinema, focusing on their first film, Nicht Versöhnt Oder es hilft nur Gewalt wo Gewalt herrscht, which presents what we will describe here as an aesthetic of non-reconciliation. A cinematographic aesthetic that emancipates from the codes generally used by the film industry to try to get closer to a less corrupted vision of reality. The resulting form of cinema will allow them to offer a different perspective on our reading of history. This film was first made in response to the fact that the German people claim to be reconciled with its history, whereas for our filmmakers it was not at all the case at the time. We will show that a really political cinema for our filmmakers must bring back traces of the past repressed under the surface of a present smoothed by the ruling classes

Long-term cycling behavior of asymmetric activated carbon/MnO2 aqueous electrochemical supercapacitor

Activated carbon–MnO2 hybrid electrochemical supercapacitor cells have been assembled and characterized in K2SO4 aqueous media. A laboratory cell achieved 195,000 cycles with stable performance. The maximal cell voltage was 2V associated with 21±2Fg−1 of total composite electrode materials (including activated carbon andMnO2, binder and conductive additive) and an equivalent serie resistance (ESR) below1.3cm2. Long-life cycling was achieved by removing dissolved oxygen from the electrolyte, which limits the corrosion of current collectors. Scaling up has been realized by assembling several electrodes in parallel to build a prismatic cell. A stable capacity of 380 F and a cell voltage of 2V were maintained over 600 cycles. These encouraging results show the interest of developing such devices, including non-toxic and safer components as compared to the current organic-based devices

L’analyse de contenu, une voie d’or pour l’analyse des politiques éducatives ? Étude de cas du programme d’Histoire et éducation à la citoyenneté et de sa controverse

Cet article propose une analyse de l’influence des médias dans le cycle d’élaboration des politiques éducatives en s’appuyant sur une étude de cas portant sur la controverse de 2006 entourant le programme d’Histoire et éducation à la citoyenneté de deuxième cycle du secondaire au Québec. Nous y soulignons l’importance des médias dans l’émergence du débat au sein de la sphère publique, l’alimentation et l’amplification de ce dernier, ainsi que son incidence directe sur la décision de révision du programme par le gouvernement du Québec. Pour ce faire, nous procédons à une conceptualisation de la controverse, laquelle est décomposée en cinq grands enjeux se trouvant chacun au centre d’une confrontation entre deux dimensions. C’est à partir de cette conceptualisation que nous établissons notre grille d’analyse, puis procédons à une analyse de contenu de la version préliminaire du programme, de sa seconde version et d’une trentaine d’articles de journaux publiés entre le début de la controverse et la présentation de cette seconde version. Cette analyse nous permet d’observer que sur le plan quantitatif, la controverse a eu peu d’effet, alors que sur le plan qualitatif, nous pouvons observer quelques changements subtils, mais importants

Evolution of High Throughput Satellite Systems: Vision, Requirements, and Key Technologies

High throughput satellites (HTS), with their digital payload technology, are expected to play a key role as enablers of the upcoming 6G networks. HTS are mainly designed to provide higher data rates and capacities. Fueled by technological advancements including beamforming, advanced modulation techniques, reconfigurable phased array technologies, and electronically steerable antennas, HTS have emerged as a fundamental component for future network generation. This paper offers a comprehensive state-of-the-art of HTS systems, with a focus on standardization, patents, channel multiple access techniques, routing, load balancing, and the role of software-defined networking (SDN). In addition, we provide a vision for next-satellite systems that we named as extremely-HTS (EHTS) toward autonomous satellites supported by the main requirements and key technologies expected for these systems. The EHTS system will be designed such that it maximizes spectrum reuse and data rates, and flexibly steers the capacity to satisfy user demand. We introduce a novel architecture for future regenerative payloads while summarizing the challenges imposed by this architecture

Procès et environnement : quelles actions en justice pour l’environnement ?

Les travaux publiés dans cet ouvrage sont le fruit de recherches collectives menées en France, à travers l’ensemble des ordres juridiques (constitutionnel, administratif, judiciaire) mais aussi au Japon et au Québec. Il s’agit de porter un regard comparatiste sur les actions en justice en matière de protection de l’environnement, sous le prisme de la stratégie contentieuse. Sont appréhendés tout à la fois les spécificités de tel ou tel type d’action, les difficultés juridiques propres aux actions formées par des associations, les stratégies que celles-ci doivent privilégier ainsi que les risques auxquels elles s’exposent en agissant en justice, les potentialités de l’action de groupe, mais aussi celle de l’octroi de droits à la nature elle-même

The Agrodiversity Experiment: three years of data from a multisite study in intensively managed grasslands

Intensively managed grasslands are globally prominent ecosystems. We investigated whether experimental increases in plant diversity in intensively managed grassland communities can increase their resource use efficiency. This work consisted of a coordinated, continental-scale 33-site experiment. The core design was 30 plots, representing 15 grassland communities at two seeding densities. The 15 communities were comprised of four monocultures (two grasses and two legumes) and 11 four-species mixtures that varied in the relative abundance of the four species at sowing. There were 1028 plots in the core experiment, with another 572 plots sown for additional treatments. Sites agreed a protocol and employed the same experimental methods with certain plot management factors, such as seeding rates and number of cuts, determined by local practice. The four species used at a site depended on geographical location, but the species were chosen according to four functional traits: a fast-establishing grass, a slow-establishing persistent grass, a fast-establishing legume, and a slow-establishing persistent legume. As the objective was to maximize yield for intensive grassland production, the species chosen were all high-yielding agronomic species. The data set contains species-specific biomass measurements (yield per species and of weeds) for all harvests for up to four years at 33 sites. Samples of harvested vegetation were also analyzed for forage quality at 26 sites. Analyses showed that the yield of the mixtures exceeded that of the average monoculture in >97% of comparisons. Mixture biomass also exceeded that of the best monoculture (transgressive overyielding) at about 60% of sites. There was also a positive relationship between the diversity of the communities and aboveground biomass that was consistent across sites and persisted for three years. Weed invasion in mixtures was very much less than that in monocultures. These data should be of interest to ecologists studying relationships between diversity and ecosystem function and to agronomists interested in sustainable intensification. The large spatial scale of the sites provides opportunity for analyses across spatial (and temporal) scales. The database can also complement existing databases and meta-analyses on biodiversity–ecosystem function relationships in natural communities by focusing on those same relationships within intensively managed agricultural grasslands

Applications of power to gas technologies in emerging electrical systems

Abstract The energy sector is undergoing substantial changes in order to promote better efficiency, increase the use of renewable energy, reduce emissions and effectively deploy technologies to trade off costs and benefits One emerging solution is the application of the Power-to-Gas technology, which can be used for different purposes. In recent years, Power-to-Gas has been studied to understand the role it could play in the electrical system. This paper has the aims of analysing the existing literature about the Power-to-Gas technology in detail, by considering some solutions that have a direct impact on the electrical system (in particular electrolyser and CO2 production) and applications in the different sectors of the electricity value chain (i.e., generation, transmission, distribution and utilisation). This paper sets out the conceptual aspects that are necessary to include Power-to-Gas facilities in a more comprehensive analysis framework of the operation of the electrical system in various sectors. Some perspectives concerning new Power-to-Gas applications are also presented for each sector, and some promising aspects that are expected to play a relevant role in the future technical and economic evolution of electrical systems are discussed