【Brownbag】Sparse Clustered Networks with Exact Aggregation
2026/06/26
研討會日期 : 2026-06-26
時間 : 12:10
主講人 : Mr. Yu-Chi Hsieh (謝羽騏)
地點 : Conference Room B110
演講者簡介 : Yu-Chi Hsieh is currently a Ph.D. student at Northwestern University with research interests in Microeconomic Theory, Networks, and Political Economy.
演講摘要 : We propose a continuum model of sparse clustered networks and use it to study strategic network formation for information diffusion. Agents invest in strong and weak ties to become better informed before valuable information diffuses. Strong ties connect agents within social circles, while weak ties bridge across them. Each agent has finitely many connections, and her local neighborhood is genuinely random. For this model, we prove an exact law of large numbers (ELLN): every bounded finite-radius local outcome has a deterministic cross-sectional average. Agents' probabilities of being informed, equilibrium link investments, the first-best benchmark, and welfare comparisons thus all reduce to tractable finite-dimensional equations. We show that weak ties are more valuable at the margin because they bring information from outside local clusters. Nevertheless, weak ties are underprovided in equilibrium, because agents do not internalize how weak ties make them better sources of information for their strong-tie neighbors. Equilibrium networks are therefore too clustered.
