# CES Economic Theory Seminar

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The Economic Theory workshop is a weekly seminar taking place on fridays 12-13h at the Maison des Sciences Economiques (106-110 Boulverd de l'Hopital). This seminar is a venue for theoretical work in Economics and for work drawing on quantitative methods in Economics. Defined by an approach rather than by a specific theme, the topics of the seminar can concern a variety of areas in Economics, such as (non exhaustively), micro economics, game theory, mathematical economics, decisions theory, finance or macro economics. The seminar functions as an internal workshop but also regularly greets speakers from other institutions.

Organizers: Emily Tanimura, Stéphane Zuber, Anna Bogomolnaia and Hervé Moulin,

If you want to be added to the seminar mailing list, or for any other query about the Economic Theory seminar, please feel free to contact Emily Tanimura (emily(dot)tanimura(at)univ-paris1(dot)fr).

You can add the calendar to your google calendar with the following link:

https://calendar.google.com/calendar?cid=bnNpYXFkdHFncmFiYTV1bWhqcGE0c2VrbDBAZ3JvdXAuY2FsZW5kYXIuZ29vZ2xlLmNvbQ

It is supported by the Centre d'économie de la Sorbonne, CNRS and Université Paris 1 Panthéon-Sorbonne.

Friday, March 17th, Rim Lahmandi-Ayed (CUT, Rennes School of Business and University of Carthage)

Location and time: Maison des Sciences Economiques, Room 115 , 12-13h

Title : More Competition to Alleviate Poverty? A General Equilibrium Model and An Empirical Study

Summary: In this paper, we theoretically and empirically analyze the impact of competition on poverty. We consider a general equilibrium framework with vertical preferences and compare poverty in a Monopoly setting versus a Duopoly setting considering explicitly the ownership structure. Poverty is measured by the size of the population living below an absolute poverty line. Theoretical results show that the impact of competition on poverty is contingent to the ownership structure, the poverty line and the relative dispersion of the individuals with respect to their intensity of preference for quality and sensitivity to effort: competition can improve or worsen poverty depending on the model's parameters. Empirical findings for the three poverty lines are consistent to some extent with our theoretical results.

Friday, March 24th, Stéphane Zuber (Centre d'Economie de la Sorbonne)

Location and time: Maison des Sciences Economiques, Room 115 , 12-13h

Title : Expected total utilitarianism is implied by individual and social dominance (with J. Gustafsson and D. Spears)

Summary: We provide a new axiomatic path to expected total utilitarianism, which is a core economic framework for evaluating policies and social welfare under variable population and social risk. Our innovation is a previously unrecognized combination of weak assumptions that yields expected total utilitarianism. We show that two dimensions of weak dominance (over risk and individuals) characterize a social welfare function with two dimensions of additive separability. So, social expected utility emerges merely from social statewise dominance (given other axioms). Moreover, total utilitarianism arises merely from individual stochastic dominance, which is assumed only for lives certain to exist (so this axiom does not compare life against non-existence). Further, without assuming individual preferences, we derive that the social order respects individual-level expected utility. We additionally apply our result to time-separable macroeconomic growth accounting and to individual risky choice. Our result provides an important foundation for evaluating climate change, growth, and global depopulation.

Friday, March 31st, Michel de Lara (CERMICS, Ecole des Ponts ParisTech)

Location and time: Maison des Sciences Economiques, Room 115 , 12-13h

Title : Games in Product Form and Kuhn's Equivalence Theorem (joint work with Benjamin Heymann and Jean-Philippe Chancelier)

Summary: In this talk, we introduce games in product form (GPF, based on Witsenhausen intrinsic model) as an alternative to games in extensive form (GEF, based on Kuhn's tree model). We advocate the relevance of GPF for game theory by:

providing a case of game form that is playable, but that cannot be written on a tree,

illustrating with examples the easiness and flexibility of GPF to model games with information,

discussing how to represent stochastic and Bayesian games inside the GPF formalism.

We illustrate its theoretical interest by providing a classification of information structures, a definition of perfect recall, a definition of behavioral strategies "à la Aumann" and by proving a Kuhn's Equivalence Theorem for GPF.

Friday, April 7th, Cuong Tran Viet (CES, Université Paris 1 )

Location and time: Maison des Sciences Economiques, S17 , 12-13h

Title : Incomplete Markets with a Countable Number of States: Equilibrium and No-Arbitrage

Summary: In this paper, we prove that the two-period model $\grave{a}$ la Hart with an incomplete market has an equilibrium when the number of states of nature is infinitely countable. Moreover, under some restrictions on the returns matrix, an equilibrium asset price is a no-arbitrage price. Conversely, we consider a sequence of equilibria corresponding to an increasing number of states associated with a given no-arbitrage asset price. If the limit, for the product topology, of the sequence of commodity prices is different from zero, then the limits of these prices and of the allocations (assets, commodities) constitute, together with the given asset price, an equilibrium with an infinitely countable number of states.

Friday, April 21st , Sébastian Bervoets (Aix-Marseille School of Economics )

Location and time: Maison des Sciences Economiques, S17 , 12-13h

Title :TBA

Summary: TBA

Friday, June 9th, Eric Danan (Université de Cergy)

Location and time: Maison des Sciences Économiques, S17 , 12-13h

Title :TBA

Summary: TBA

Friday, June 16th, Morgan Patty (CEPS, École normale supérieure Paris-Saclay)

Location and time: Maison des Sciences Économiques, S17 , 12-13h

Title :TBA

Summary: TBA