Anna Creti (Université Paris-Dauphine)    Titre: How Environmental Policies Spread ? A Network Approach to Diffusion in the U.S (A joint work with Côme Billard and Antoine Mandel) Résumé:  We reconstruct the network of environmental policies diffusion across American states from 1974 to 2018. Our results highlight an inefficient structure, suggesting lags in policy spreading. We identify Minnesota, California and Florida to be the main "facilitators" of the dynamics. Targeting them ensures the maximum likelihood of policy diffusion across the country. We then evaluate the determinants of the inferred network. Our results emphasize the role of contiguity and wealth in policy transmission. We also find sustainable economic systems as well as state’s expected economic losses due to climate change as critical factors of environmental policy flows. Download slides

  Speaker: Yves Achdou (LJLL, Université Paris-Diderot) Titre: A short-term model for the oil industry addressing commercial storage A joint work with C.Bertucci (CNRS), J.-M. Lasry (U. Dauphine), P.-L. Lions (Collège de France), A. Rostand (Kayrros), J. Scheinkman (Columbia U.) Résumé: We propose a mechanism for the short term dynamics of the oil market based on the interactions of several agents, namely a major agent (a monopolistic cartel), a fringe of competitive producers and a crowd of physical arbitrageurs who store the resource. The model leads to a system of two coupled non linear partial differential equations, with a new type of boundary conditions linked to constraints on the storage capacity. These boundary conditions play a key role and translate the fact that when storage is either full or empty, the cartel has an enhanced strategic power, and may tune the price of the resource. The model will be discussed in details. Numerical simulations based on a finite difference scheme will be reported. The latter result in apparently surprising facts: 1) the optimal control of the cartel (i.e. its level of production) is a discontinuous function of the state variables; 2) there is a cycle, which takes place around the shock line. These phenomena will be discussed, and it will be shown that they may explain what happened in 2015 and 2020. Download slides

Zhenjie Ren (CEREMADE, Université Paris-Dauphine)    Titre: Entropic Fictitious Play Résumé: The classical fictitious play is a common algorithm for solving games. However, once the cost functions of the players are non-convex, the method becomes hard to implement. In our study we add the entropic regulariser, a common strategy for non-convex optimisation, to the cost functions, andlook into the analog of fictitious play in this context. We shall further see that the entropic fictitious play not only helps to solve non-convex game, butalso can be used to solve optimisations on the space of probability measures, and thus can be applied to train neural networks.   Download slides

Miquel Oliu Barton (CEREMADE, Université Paris-Dauphine & Bruegel) Titre: Green zoning: An effective policy tool to tackle the Covid-19 pandemic Résumé: Green zoning has emerged as a widely used policy response to tackle the Covid-19 pandemic. ‘Green zones’—areas where the virus is under control based on a uniform set of conditions—can progressively return to normal economic and social activity levels, and mobility between them is permitted. By contrast, stricter public health measures are in place in ‘red zones’, and mobility between red and green zones is restricted. France and Spain were among the first countries to introduce green zoning in April 2020. Subsequently, more and more countries followed suit and the European Commission advocated for the implementation of a European green zoning strategy, which has been supported by the EU member states. While there remain coordination problems, green zoning has proven to be an effective strategy for containing the spread of the virus and limiting its negative economic and social impact. This strategy should provide important lessons and prove useful in future outbreaks. Research in epidemiology indicates that thoroughly implemented and operationalised green zoning can prevent the spread of a transmittable disease that is poorly understood, highly virulent, and potentially highly lethal. Finally, there is strong evidence that green zoning can reduce economic and societal damage as it avoids worst-in-class measures. A Joint work with Bary Pradelski. Download slides  

Panagiotis Andrianesis (Boston University) Computation of Convex Hull Prices in Electricity Markets with Non-Convexities using Dantzig-Wolfe Decomposition Résumé: The presence of non-convexities in electricity markets has been an active research area for about two decades. The — inevitable under current marginal cost pricing — problem of guaran- teeing that no market participant incurs losses in the day-ahead market is addressed in current practice through make-whole payments a.k.a. uplift. Alternative pricing rules have been studied to deal with this problem. Among them, Convex Hull (CH) prices associated with minimum up- lift have attracted significant attention. Several US Independent System Operators (ISOs) have considered CH prices but resorted to approximations, mainly because determining exact CH prices is computationally challenging, while providing little intuition about the price formation rationale. In this work, we describe the CH price estimation problem by relying on Dantzig-Wolfe decomposition and Column Generation, as a tractable, highly paralellizable, and exact method — i.e., yielding exact, not approximate, CH prices — with guaranteed finite convergence. More- over, the approach provides intuition on the underlying price formation rationale. A test bed of stylized examples provide an exposition of the intuition in the CH price formation. In addition, a realistic ISO dataset is used to support scalability and validate the proof-of-concept. A Joint work with Dimitris Bertsimas, Michael Caramanis & William W. Hogan Download slides