2,163 research outputs found
Reachability Analysis of Innermost Rewriting
We consider the problem of inferring a grammar describing the output of a functional program given a grammar describing its input. Solutions to this problem are helpful for detecting bugs or proving safety properties of functional programs and, several rewriting tools exist for solving this problem. However, known grammar inference techniques are not able to take evaluation strategies of the program into account. This yields very imprecise results when the evaluation strategy matters. In this work, we adapt the Tree Automata Completion algorithm to approximate accurately the set of
terms reachable by rewriting under the innermost strategy. We prove that the proposed technique is sound and precise w.r.t. innermost rewriting. The proposed algorithm has been implemented in the Timbuk reachability tool. Experiments show that it noticeably improves the accuracy of static analysis for functional programs using the call-by-value evaluation strategy
La difficile question des biens publics en agriculture : réflexions autour des outils économiques
[Paper in French] The European Union (EU) has gradually increased the importance of environmental issues in the objectives and instruments of the Common Agricultural Policy (CAP). Agro-environmental schemes, enforced within all of the Member States since the 90âs, are contracted by the farmers on a voluntary basis. Since the enforcement, in 2005, of the cross-compliance of the whole CAP direct payment, almost all farms in the EU are now subject to environmental and sanitary constraints. The efficiency of these mechanisms and their consistency with pre-existing instruments are nonetheless questionable, as shown by various research and evaluation reports. However, the provision of public goods through agriculture can be seen as a legitimate objective of the agricultural policy, even though the clear wish to propose a simplified CAP does not prima facie fit with a broad consideration of the public good issue in agriculture. This article proposes a critical review of the CAP in reference to that objective. A particular attention is paid to the provision of environmental public goods based on the assessment of past actions and recent progress. Besides, we question whether the CAP should, and could, support the farmers in meeting objectives in terms of environmental production. Our analysis intends to shed light on these issues which are currently largely debated. Finally, we present perspectives offered by economic instruments that could be mobilised in view of delineating the different options for the future CAP (post-2013). Within the next years technological progress, market forces, and the impacts of climate change will probably be the most important drivers of the evolution of agricultural structures, and therefore of the provision of environmental public goods. With its influence on the various determinants of the agricultural activities, the CAP has a key-role to play in the provision of such public goods. Hence, the future policy will have to pay greater attention to public goods if, in response to the social demand, it is decided to make them one of the backbones of the new CAP design. However, such a greening reorientation of the policy can turn thorny with respect to the maintenance of the initial objectives of the European policy: securing farmsâ viability and maintaining the competitiveness of the agricultural sector within the EU.Common Agricultural Policy, public goods, agriculture, environment, economic instruments
Stochastic Inference of Surface-Induced Effects using Brownian Motion
Brownian motion in confinement and at interfaces is a canonical situation,
encountered from fundamental biophysics to nanoscale engineering. Using the
Lorenz-Mie framework, we optically record the thermally-induced tridimensional
trajectories of individual microparticles, within salty aqueous solutions, in
the vicinity of a rigid wall, and in the presence of surface charges. We
construct the time-dependent position and displacement probability density
functions, and study the non-Gaussian character of the latter which is a direct
signature of the hindered mobility near the wall. Based on these distributions,
we implement a novel, robust and self-calibrated multifitting method, allowing
for the thermal-noise-limited inference of diffusion coefficients
spatially-resolved at the nanoscale, equilibrium potentials, and forces at the
femtoNewton resolution
GAIA: a benchmark for General AI Assistants
We introduce GAIA, a benchmark for General AI Assistants that, if solved,
would represent a milestone in AI research. GAIA proposes real-world questions
that require a set of fundamental abilities such as reasoning, multi-modality
handling, web browsing, and generally tool-use proficiency. GAIA questions are
conceptually simple for humans yet challenging for most advanced AIs: we show
that human respondents obtain 92\% vs. 15\% for GPT-4 equipped with plugins.
This notable performance disparity contrasts with the recent trend of LLMs
outperforming humans on tasks requiring professional skills in e.g. law or
chemistry. GAIA's philosophy departs from the current trend in AI benchmarks
suggesting to target tasks that are ever more difficult for humans. We posit
that the advent of Artificial General Intelligence (AGI) hinges on a system's
capability to exhibit similar robustness as the average human does on such
questions. Using GAIA's methodology, we devise 466 questions and their answer.
We release our questions while retaining answers to 300 of them to power a
leader-board available at https://huggingface.co/gaia-benchmark
Competition-based Model of Pruning: Applications to Apple Trees
International audienceno abstrac
Clathration of Volatiles in the Solar Nebula and Implications for the Origin of Titan's atmosphere
We describe a scenario of Titan's formation matching the constraints imposed
by its current atmospheric composition. Assuming that the abundances of all
elements, including oxygen, are solar in the outer nebula, we show that the icy
planetesimals were agglomerated in the feeding zone of Saturn from a mixture of
clathrates with multiple guest species, so-called stochiometric hydrates such
as ammonia hydrate, and pure condensates. We also use a statistical
thermodynamic approach to constrain the composition of multiple guest
clathrates formed in the solar nebula. We then infer that krypton and xenon,
that are expected to condense in the 20-30 K temperature range in the solar
nebula, are trapped in clathrates at higher temperatures than 50 K. Once
formed, these ices either were accreted by Saturn or remained embedded in its
surrounding subnebula until they found their way into the regular satellites
growing around Saturn. In order to explain the carbon monoxide and primordial
argon deficiencies of Titan's atmosphere, we suggest that the satellite was
formed from icy planetesimals initially produced in the solar nebula and that
were partially devolatilized at a temperature not exceeding 50 K during their
migration within Saturn's subnebula. The observed deficiencies of Titan's
atmosphere in krypton and xenon could result from other processes that may have
occurred both prior or after the completion of Titan. Thus, krypton and xenon
may have been sequestrated in the form of XH3+ complexes in the solar nebula
gas phase, causing the formation of noble gas-poor planetesimals ultimately
accreted by Titan. Alternatively, krypton and xenon may have also been trapped
efficiently in clathrates located on the satellite's surface or in its
atmospheric haze.Comment: Accepted for publication in The Astrophysical Journa
Disaster Operations Management: an Empirical Study from Thailand
Disasters have unpredictable and deleterious impacts on modern societies. While recent operations management research has increasingly focused on disaster operations, only a few studies have examined the recovery phase of post-disaster operations. This research presents an overview of Disaster Operations Management as well as an empirical study using econometrics analysis to examine the recovery phase of post-disaster operations. The results suggest that when resources are scarce, at a strategic level we need to understand where to begin when planning the recovery process. This study is an exploratory analysis of the question of how flooding affects per capita income in areas with different levels of industrialization. We developed multiple regression models using panel data from Thailand to examine this effect, finding that flooding in a previous year has a positive effect on areas with a low level of industrialization, but a negative one on highly industrialized areas, meaning the residents of the latter are affected differently. Our results suggest the level of industrialization impacts the effectiveness of the recovery process. Finally, we discuss the implications of the study as well as suggestions for future research
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