César Barilla

I am an economic theorist. I am broadly interested in strategic behaviour and interactions in complex, often dynamically changing environments; how information is acquired and processed; and how this interacts with the design of economic institutions. I received my PhD from Columbia in 2025.

Research

Working Papers

• When and what to learn in a changing world
  Short abstract | working paper Extended abstract in EC'25
  When learning repeatedly about evolving circumstances, how do the choices of frequency and content interact? I propose a general and tractable model to tackle this question, encompassing both the extreme cases of pure timing friction, pure informational cost, and their mixture.
• Ancestral origins of environmental (in)attention with Palaash Bhargava
  Short abstract | working paper
  How does the climatic experience of previous generations affect today's attention to environmental questions? Combining multiple contemporary surveys and ethnic group-level cultural records with a model of cultural selection on costly attention, we show that ancestral climate anomalies have a lasting U-shaped effect on environmental concern.
• coming soon The fiscal limits of efficient trade with Toàn Lê and Saara Hämäläinen
  Short abstract
  If a designer is willing to subsidize efficient trade, but only up to a point, what minimal worst-case deficit can they guarantee and what mechanism achieves it?
• coming soon Dynamic market design in large economies with Charlotte Martres and Olivier Tercieux
  Short abstract
  How can we model markets where centralized assignments take place repeatedly, and priorities and payoffs may depend on assignments? How can priorities, which shape dynamic incentives, be used as a design instrument to address distributional concerns in such markets?

Publications

• The dynamics of instability with Duarte Gonçalves
  Theoretical Economics, 2024
  Short abstract | published version | working paper
  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
  Short abstract | published version | working paper | additional figures
  We propose a 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.

Teaching

Instructor

• Further Mathematical Methods Economics MPhil, University of Oxford — 2026
• Game Theory Undergraduate Elective, Columbia University — 2022, 2023
• MA Math Camp Economics MA, Columbia University — 2021

Teaching Assistant

• MA Microeconomics Economics MA, Columbia University — 2023, 2025
• PhD Microeconomic Analysis II Economics PhD, Columbia University — 2022
• Math Methods for Economists Economics MA, Columbia University — 2020, 2021