After The Hague, Bonn and Marrakech : the future international market for emissions permits and the issue of hot air

The main objective of this paper is to assess the Bonn-Marrakech agreement, in terms of abatement cost and emission trading as compared with the initial agreement reached in Kyoto (the Kyoto Protocol).CLIMATE CHANGE ; EMISSIONS TRADING ; INTERNATIONAL AGREEMENT

Teaching About the « Economic Crisis » Today. The Example of French « Economic and Social Sciences »

Purpose: In France at the high school the subject matter “Sciences Économiques et Sociales” (economic and social sciences) deals with the present economic crisis. We study the ways it is taught about: words, and explanatory patterns. Design/methodology/approach: We use a specific approach, that we call “semantic holism”, conceiving subject contents as the product of a dual process of didactization and of axiologization of reference knowledge. That implies relating these contents to the social value system and, especially, to the lexicon, set of keywords through which people must think and talk at some point. The analysis starts from the examination of economic and social sciences syllabuses and teaching resources, and leads us to highlight the predominance of the references to standard economics, but this predominance cannot be justified by the state of scientific knowledge.Findings: We show on the contrary a lexicon effect: the subject key notions have been selected in accordance to the lexicon keywords. Therefore the proposed contents seem far from the objective to understanding the major issues at stake today. Research limitations/implications: Then further researches must focus on the ways of teaching about the crisis in spite of the present lexicon

Additional Results and Extensions for the paper "Probabilistic bounds on the k−k-Traveling Salesman Problem and the Traveling Repairman Problem''

This technical report provides additional results for the main paper ``Probabilistic bounds on the $k-$Traveling Salesman Problem ($k-$TSP) and the Traveling Repairman Problem (TRP)''. For the $k-$TSP, we extend the probabilistic bounds derived in the main paper to the case of distributions with general densities. For the TRP, we propose a utility-based notion of fairness and derive constant-factor probabilistic bounds for this objective, thus extending the TRP bounds from the main paper to non-linear utilities

Probabilistic bounds on the k−k-Traveling Salesman Problem and the Traveling Repairman Problem

The $k-$traveling salesman problem ($k$-TSP) seeks a tour of minimal length that visits a subset of $k\leq n$ points. The traveling repairman problem (TRP) seeks a complete tour with minimal latency. This paper provides constant-factor probabilistic approximations of both problems. We first show that the optimal length of the $k$-TSP path grows at a rate of $\Theta\left(k/n^{\frac{1}{2}\left(1+\frac{1}{k-1}\right)}\right)$. The proof provides a constant-factor approximation scheme, which solves a TSP in a high-concentration zone -- leveraging large deviations of local concentrations. Then, we show that the optimal TRP latency grows at a rate of $\Theta(n\sqrt n)$. This result extends the classical Beardwood-Halton-Hammersley theorem to the TRP. Again, the proof provides a constant-factor approximation scheme, which visits zones by decreasing order of probability density. We discuss practical implications of this result in the design of transportation and logistics systems. Finally, we propose dedicated notions of fairness -- randomized population-based fairness for the $k$-TSP and geographical fairness for the TRP -- and give algorithms to balance efficiency and fairness

Memory-Constrained Algorithms for Convex Optimization via Recursive Cutting-Planes

We propose a family of recursive cutting-plane algorithms to solve feasibility problems with constrained memory, which can also be used for first-order convex optimization. Precisely, in order to find a point within a ball of radius $\epsilon$ with a separation oracle in dimension $d$ -- or to minimize $1$-Lipschitz convex functions to accuracy $\epsilon$ over the unit ball -- our algorithms use $\mathcal O(\frac{d^2}{p}\ln \frac{1}{\epsilon})$ bits of memory, and make $\mathcal O((C\frac{d}{p}\ln \frac{1}{\epsilon})^p)$ oracle calls, for some universal constant $C \geq 1$. The family is parametrized by $p\in[d]$ and provides an oracle-complexity/memory trade-off in the sub-polynomial regime $\ln\frac{1}{\epsilon}\gg\ln d$. While several works gave lower-bound trade-offs (impossibility results) -- we explicit here their dependence with $\ln\frac{1}{\epsilon}$, showing that these also hold in any sub-polynomial regime -- to the best of our knowledge this is the first class of algorithms that provides a positive trade-off between gradient descent and cutting-plane methods in any regime with $\epsilon\leq 1/\sqrt d$. The algorithms divide the $d$ variables into $p$ blocks and optimize over blocks sequentially, with approximate separation vectors constructed using a variant of Vaidya's method. In the regime $\epsilon \leq d^{-\Omega(d)}$, our algorithm with $p=d$ achieves the information-theoretic optimal memory usage and improves the oracle-complexity of gradient descent

Non-stationary Contextual Bandits and Universal Learning

We study the fundamental limits of learning in contextual bandits, where a learner's rewards depend on their actions and a known context, which extends the canonical multi-armed bandit to the case where side-information is available. We are interested in universally consistent algorithms, which achieve sublinear regret compared to any measurable fixed policy, without any function class restriction. For stationary contextual bandits, when the underlying reward mechanism is time-invariant, [Blanchard et al.] characterized learnable context processes for which universal consistency is achievable; and further gave algorithms ensuring universal consistency whenever this is achievable, a property known as optimistic universal consistency. It is well understood, however, that reward mechanisms can evolve over time, possibly depending on the learner's actions. We show that optimistic universal learning for non-stationary contextual bandits is impossible in general, contrary to all previously studied settings in online learning -- including standard supervised learning. We also give necessary and sufficient conditions for universal learning under various non-stationarity models, including online and adversarial reward mechanisms. In particular, the set of learnable processes for non-stationary rewards is still extremely general -- larger than i.i.d., stationary or ergodic -- but in general strictly smaller than that for supervised learning or stationary contextual bandits, shedding light on new non-stationary phenomena

Après La Haye, Bonn et Marrakech : le futur marché international des permis de droits d'émissions et la question de l'air chaud

L'objectif principal de ce papier est d'évaluer quantitativement l'accord Bonn-Marrakech, en termes de coûts de réductions et de marché d'émissions, en comparaison avec l'accord initial de Kyoto.MARCHE DE PERMIS ; CHANGEMENT CLIMATIQUE ; ACCORD INTERNATIONAL

Négociation internationale sur le climat : conserver les normes du régime Rio-Kyoto

Les menaces que le changement climatique fait peser sur l'environnement global pose un problème d'action collective qui est traité dans un cadre de coopération inter étatique de type régime international, le régime climatique Rio-Kyoto.Ce papier vise à analyser les caractéristiques de ce régime, les propositions aujourd'hui discutées pour son évolution future, enfin les architectures actuellement privilégiées par deux des acteurs majeurs de la négociation internationale, les Etats-Unis et l'Union Européenne. Dans une première section nous dégagerons donc les caractéristiques principales de ce régime à travers ses éléments constitutifs qui sont en particulier un ensemble de principes et normes et de règles et procédures. Dans le cadre des règles et procédures, il est prévu de commencer de définir, à partir de 2005, de nouveaux engagements pour la suite. Les Etats doivent présenter des propositions dans ce sens. La deuxième section examinera les propositions qui sont d'ores et déjà formulées et posera la question de savoir si elles prolongent le régime de Rio-Kyoto ou s'inspirent d'autres principes et normes.Enfin la troisième section sera consacrée aux scénarios et architectures privilégiées respectivement par les Etats-Unis et par l'Europe et tentera de montrer que le respect des principes et règles du régime Rio-Kyoto est sans doute une condition de la poursuite, au plan international, d'objectifs climatiques ambitieuxchangement climatique; protocole de Kyoto; régime international; négociation