MobileCity: An Efficient Framework for Large-Scale Urban Behavior Simulation

Generative agents offer promising capabilities for simulating realistic urban behaviors. However, existing methods oversimplify transportation choices in modern cities, and require prohibitive computational resources for large-scale population simulation. To address these limitations, we first present a virtual city that features multiple functional buildings and transportation modes. Then, we conduct extensive surveys to model behavioral choices and mobility preferences among population groups. Building on these insights, we introduce a simulation framework that captures the complexity of urban mobility while remaining scalable, enabling the simulation of over 4,000 agents. To assess the realism of the generated behaviors, we perform a series of micro and macro-level analyses. Beyond mere performance comparison, we explore insightful experiments, such as predicting crowd density from movement patterns and identifying trends in vehicle preferences across agent demographics.

SimUSER: Simulating User Behavior with Large Language Models for Recommender System Evaluation

Recommender systems play a central role in numerous real-life applications, yet evaluating their performance remains a significant challenge due to the gap between offline metrics and online behaviors. Given the scarcity and limits (e.g., privacy issues) of real user data, we introduce SimUSER, an agent framework that serves as believable and cost-effective human proxies. SimUSER first identifies self-consistent personas from historical data, enriching user profiles with unique backgrounds and personalities. Then, central to this evaluation are users equipped with persona, memory, perception, and brain modules, engaging in interactions with the recommender system. SimUSER exhibits closer alignment with genuine humans than prior work, both at micro and macro levels. Additionally, we conduct insightful experiments to explore the effects of thumbnails on click rates, the exposure effect, and the impact of reviews on user engagement. Finally, we refine recommender system parameters based on offline A/B test results, resulting in improved user engagement in the real world.