从Fermat大定理看数学问题在数学发展中的作用

回顾费马大定理的解决过程,从一个侧面论述了数学问题对数学发展的推动作用.     

L’accountability à l’épreuve des incertitudes : le mandat des acheteurs d’énergie

Based on a survey of energy buyers in big industries, this article inquires into the different ways of explaining the actions they perform in situations of high, uncontrolled uncertainty. Describing energy buyers’ activities, the uncertainties and contradictions affecting them, shows how hard it is to explain them, make them visible or justify the decisions made. Energy buyers develop two forms of “accountability”: they claim to have been granted decision-making powers and ask to be evaluated on the basis of their results; or else they “socialize” their activities by involving corporate managers in decision-making. It is argued that “accountability” is stabilized in line with a collective learning process where the experience of uncertainty has a key place.     

Le marché comme rencontre d’activités de régulation : initiatives et innovations dans l’approvisionnement bio et local de la restauration collective

How to apply Jean-Daniel Reynaud's theory of social regulation to market relations? When applied to the results drawn from fieldwork on the supplying of organic and local produce to catering businesses serving public institutions in France, this grid of analysis shows that organizing this supply chain involves many activities of regulation. An explanation is provided about how hard existing regulations make it to search for local produce. Two contrasting cases show the degree to which the parties involved can skirt around existing regulations and also, use certain regulations to construct new ones. The innovative regulations that enter into application are qualified as being “joint”, since they stem from the efforts of the parties in catering and in agriculture to agree about how to organize transactions, which had previously been done through the work of market middlemen. In that case, instead of reasoning in terms of a pre-existing supply and demand, we have to understand how supply and demand gradually take shape through the process of working out regulations.     

La dynamique de la vocation : les évolutions de la rationalisation de l’engagement au travail des danseurs de ballet

The commitment to one's work, with body and soul involvement is a key issue in the study of vocation-driven occupations. In such callings, the aspirations that are socially constructed and experienced as vocations have been shown to provide meaning and direction to one's commitment. However, this study of Paris Opera ballet dancers shows that realizing one's aspirations are impossible to achieve does not necessarily result in quitting, nor retraining. Changes in the way dancers relate to their work are studied using sequential analysis, to examine which social factors may explain how this involvement's meaning is maintained. The analysis identifies some processes of vocation recomposition. Thus revealing, behind the professional careers, the “moral careers” of the vocation.     

Anticiper ou temporiser : injonctions environnementales et recompositions des identités professionnelles en céréaliculture

Questions about the modernization of farming, given its environmental impact, are leading French farmers to rework their occupational identities. This is studied by comparing cereal growers who practice “integrated protection” — a form of agriculture that saves on input — with their “conventional” colleagues. Given the high degree of uncertainty about the standards that will be imposed, cereal farmers have adopted positions that contrast with regard to: the future (anticipating vs. stalling for time), “professional excellence” (whether or not to accept lower yields) and risks (whether to adopt strategies turned toward vigilance or toward insurance). The diffusion of innovative farming practices is limited owing to their lack of legitimacy, which leads farmers to explore the possibilities for obtaining legitimation from outside the profession.     

三阶线性齐次微分方程解的Sturm比较定理

研究了一类三阶线性齐次微分方程解的Sturm比较定理的理论,在三阶线性齐次微分方程的Sturm基本定理的基础上得出了Sturm比较定理,所得结论推广了现有文献的相应结果。     

Functional Estimation of a Density Under a New Weak Dependence Condition

The purpose of this paper is to prove, through the analysis of the behaviour of a standard kernel density estimator, that the notion of weak dependence defined in a previous paper (cf. Doukhan & Louhichi, 1999) has sufficiently sharp properties to be used in various situations. More precisely we investigate the asymptotics of high order losses, asymptotic distributions and uniform almost sure behaviour of kernel density estimates. We prove that they are the same as for independent samples (with some restrictions for a.s. behaviours). Recall finally that this weak dependence condition extends on the previously defined ones such as mixing, association and it allows considerations of new classes such as weak shifts processes based on independent sequences as well as some non-mixing Markov processes.     

Boosting with Bayesian stumps

Boosting is a new, powerful method for classification. It is an iterative procedure which successively classifies a weighted version of the sample, and then reweights this sample dependent on how successful the classification was. In this paper we review some of the commonly used methods for performing boosting and show how they can be fit into a Bayesian setup at each iteration of the algorithm. We demonstrate how this formulation gives rise to a new splitting criterion when using a domain-partitioning classification method such as a decision tree. Further we can improve the predictive performance of simple decision trees, known as stumps, by using a posterior weighted average of them to classify at each step of the algorithm, rather than just a single stump. The main advantage of this approach is to reduce the number of boosting iterations required to produce a good classifier with only a minimal increase in the computational complexity of the algorithm.     

高阶拟线性时滞差分方程非振动解的存在性与渐近性

考虑一类高阶拟线性时滞差分方程给出了存在无界非振动解的充要条件。     

Combinatorial Optimization in Real-Time Scheduling: Theory and Algorithms

Real-time computer systems are essential for many applications, such as robot control, avionics, medical instrumentation, manufacturing, etc. The correctness of the system depends on the temporal correctness as well as the functional correctness of the task executions. In order to assure temporal correctness it is necessary that the resources be scheduled to meet the temporal requirements of applications. When we consider the problem of nonpreemptive scheduling of a set of tasks in a processor for which no feasible solution exists, some tasks may have to be rejected so that a schedule can be generated for the rest. In this paper, we consider the problem of generating an optimal schedule such that the number of rejected tasks is minimized, and then the finish time is minimized for the accepted tasks. We propose to use an analytic approach to solve this problem. We first discuss the super sequence based technique which was originally proposed for reducing the search space in testing the feasibility of a task set. Then we show by the Conformation theorem that the super sequence constructed from the task set also provides a valid and reduced search space for the optimization problem. While the complexity of our scheduling algorithm in the worst case remains exponential, our simulation results show that the cost is reasonable for the average case.