Skip to main content
About HEC About HEC Faculty & Research Faculty & Research Master’s programs Master’s programs MBA Programs MBA Programs PhD Program PhD Program Executive Education Executive Education Summer School Summer School HEC Online HEC Online About HEC Overview Overview Who
We Are Who
We Are
Egalité des chances Egalité des chances HEC Talents HEC Talents International International Campus
Life Campus
Life
Sustainability Sustainability Diversity
& Inclusion Diversity
& Inclusion
Stories Stories The HEC
Foundation The HEC
Foundation
Coronavirus Coronavirus
Faculty & Research Overview Overview Faculty Directory Faculty Directory Departments Departments Centers Centers Chairs Chairs Knowledge Knowledge Master’s programs Master in
Management Master in
Management
Master in
International Finance Master in
International Finance
Specialized
Masters Specialized
Masters
Ecole Polytechnique
-HEC programs Ecole Polytechnique
-HEC programs
Dual-Degree
programs Dual-Degree
programs
Visiting
students Visiting
students
Certificates Certificates Student
Life Student
Life
MBA Programs MBA MBA Executive MBA Executive MBA TRIUM EMBA TRIUM EMBA PhD Program Overview Overview HEC Difference HEC Difference Program details Program details Research areas Research areas HEC Community HEC Community Placement Placement Job Market Job Market Admissions Admissions Financing Financing Executive Education Executive Masters Executive Masters Executive Certificates Executive Certificates Executive short programs Executive short programs Online Online Companies Companies Executive MBA Executive MBA Infinity Pass Infinity Pass Summer School Youth Programs Youth Programs Summer programs Summer programs HEC Online Overview Overview Degree Program Degree Program Executive certificates Executive certificates MOOCs MOOCs Summer Programs Summer Programs
PhD Program

PhD Dissertation Defense, Wei Zhao, Economics and Decision Sciences

Congratulations to Dr Wei Zhao, Economics and Decision Sciences specialization, who successfully defended his Doctoral Dissertation at HEC Paris, on June 21, 2022. Dr Zhao has accepted a position at Renmin University - School of Economics (China) as Assistant Professor, starting September, 2022.

Specialization: Economics and Decision Sciences

Topic: Essays in Information Design and network theory

Supervisor: Tristan Tomala, Professor, HEC Paris 

Jury Members:

  • Bruno BIAIS, Professor, HEC Paris 
  • Vasiliki SKRETA, Professor, University of Texas at Austin (USA)
  • Eduardo PEREZ, Associate Professor, Sciences Po Paris (France) 
  • Ludovic Renou, Professor, Queen Mary University (UK)
  • Tristan TOMALA Professor, HEC Paris - supervisor

 

Abstract:
This thesis studies dynamic information design and network theory. The thesis is composed of four chapters. In the first chapter, I study informa tion design in a dynamic moral hazard environment. An agent and an expert face a common uncertainty regarding the effectiveness of a collective decision. The agent bears the cost of effort of information ac quisition and makes the final decision. The expert is the only observer of research outcomes and provides information over time to the agent. Both parties are equally affected by the decision. I show that one opti mal information policy consists in disclosing truthfully with delay. In the first periods of time, the delay is zero, then strictly increases and finally vanishes. By the time the delay decreases back to zero, the agent has taken the decision with probability one. In the second chapter, we study a dynamic principal-agent problem, where the sole instrument the principal has to incentivize the agent is the disclosure of informa tion. The principal aims at maximizing the (discoun ted) number of times the agent chooses the principal’s preferred action. We show that there exists an optimal contract, where the principal stops disclosing informa tion as soon as its most preferred action is a static best reply for the agent, or else continues disclosing information until the agent perfectly learns the princi pal’s private information. If the agent perfectly learns the state, he learns it in finite time with probability one ; the more patient the agent, the later he learns it. In the third chapter, two types of intervention are commonly implemented in networks : characteristic intervention which influences individuals’ intrinsic incentives, and structural intervention which targets at the social links among individuals. In this paper we provide a general framework to evaluate the distinct equilibrium effects of both types of interventions. We identify a hidden equivalence between a structural intervention and an endogenously determined characteristic intervention. Compared with existing approaches in the literature, the perspective from such an equivalence provides several advantages in the analysis of targeting inter ventions of the network structure. We present a wide range of applications of our theory, including deter mining whether a structural intervention is beneficial, identifying the most wanted criminal(s) in delinquent networks, and targeting the key bridge nodes for dis connected communities. In the last chapter, we study the problem of designing efficient network sequen tially. In each period, the planner connects two unlin ked agents in the network formed in previous period, then the agents play a game with local complemen tarity under the newly formed network. The planner benefits from the entire discounted stream of equili brium welfare. We show that, forming a nested split graph in each period is an optimal strategy for the planner for any specific values of discount factors. Mo reover, when the planner heavily discounts future wel fare, the optimal strategy induces a quasi-complete graph in each period regardless of the strength of complementary effect. Our paper therefore provides a micro-foundation for quasi-complete network since it is formed under greedy algorithm. We also discuss the robustness of these results under non-linear best response and heterogeneous agents.
 

Keywords : Dynamic Information Design ; Social Network Theory ; Structural Intervention