César Barilla

Welcome!

I am an economic theorist; my research interests include information economics and dynamic games.

I am currently a Postdoctoral Prize Research Fellow at Nuffield College, Oxford.

I completed my PhD at Columbia University in May 2025.

Research

Publications

• The Dynamics of Instability with Duarte Gonçalves
  Theoretical Economics, 2024
  published version | working paper
  
  Short abstract

  Even if pure instability does not generate any short term expected gains, players with opposed interests can leverage it to obtain long term changes. In equilibrium, the least favored player uses instability in a decreasing manner as we get closer to a stable state; long run outcome exhibit path dependency and can sustain high inequity.
• A Mean-Field Game Model for the Evolution of Cities with Guillaume Carlier and Jean-Michel Lasry
  Journal of Dynamics and Games, 2021
  published version | working paper | additional figures
  
  Short abstract

  We propose a MFG model for the evolution of residents and firms densities, coupled both by labour market equilibrium conditions and competition for land use; the former induces a new optimal transport coupling in the system of two HJB and two Fokker-Planck equations. This MFG has a convex potential which enables us to find weak solutions by a variational approach. In the case of quadratic Hamiltonians, we reformulate the problem in Lagrangian terms and develop a numerical solution method.

Working Papers

• When and what to learn in a changing world
  Extended abstract in EC'25
  
  Abstract

  A decision-maker periodically acquires information about a changing state, controlling both the timing and content of updates. I characterize optimal policies using a decomposition of the dynamic problem into optimal stopping and static information acquisition problems. Eventually, information acquisition either stops or follows a simple cycle, with updates occurring at regular intervals and leading to consistent certainty levels; this enables precise characterizations of long run information acquisition across environments. In the limit as fixed costs vanish it is optimal to trade-off quality for frequency; surprisingly, this entails that both belief and action changes become lumpier. I highlight applications to portfolio diversification and asymmetries between safe and risky choices.
• Ancestral origins of attention to environmental issues with Palaash Bhargava
  Abstract

  How does the climatic experience of previous generations affect today's attention to environmental questions? Using self-reported beliefs and environmental themes in folklore, we show empirically that the realized intensity of deviations from typical climate conditions in ancestral generations influences how much descendants care about the environment. The effect exhibits a U-shape where more stable and more unstable ancestral climates lead to higher attention today, with a dip for intermediate realizations. We propose a theoretical framework where the value of costly attention to environmental conditions depends on the perceived stability of the environment, prior beliefs about which are shaped through cultural transmission by the experience of ethnic ancestors. The U-shape is rationalized by a double purpose of learning about the environment: optimal utilization of typical conditions and protection against extreme events.

Older & inactive work

• Dynamic information acquisition with memory loss with Arslan Ali
  Abstract

  Does memory loss lead to more or less information acquisition? When information may be forgotten before it can be used to make decisions, the marginal value of an individual signal is subject to two opposite forces: it decreases since it is less likely to improve decisions and improves since having more information may improve overall retention. This leads to asymmetric distortions in sequential optimal information acquisition: memory loss leads to lower standards for information that confirms the status quo but over-confirmation for information that contradicts it.
• Stability with complementarities in decentralized many-to-one matching markets
  Masters Thesis, Paris School of Economics, 2019
  
• Optimal transport coupling in multi-population mean field games
  Masters Thesis, UPMC Jussieu, 2018
  

Teaching

Instructor

• Game Theory (Summer 2022, Summer 2023)
  Undergraduate Elective, Columbia University

• MA Math Camp (Summer 2021)
  Economics MA, Columbia University
  Course Page

Teaching Assistant

• MA Microeconomics (Spring 2023, Spring 2025)
  Economics MA, Columbia University
  Teaching Assistant for Professor Guillaume Haeringer

• PhD Microeconomic Analysis II (Spring 2022)
  Economics PhD, Columbia University
  Teaching Assistant for Professors Yeon-Koo Che and Elliot Lipnowski

• Math Methods for Economists (Fall 2020, Fall 2021)
  Economics MA, Columbia University
  Teaching Assistant for Professor Evan Sadler (2021) and Professor Ceyhun Elgin (2020)