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Lijian Lu

Publications and source records attributed to Lijian Lu.

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From Optimization to Satisficing: Robust Screening under Distributional Ambiguity

This study investigates a robust screening problem under distributional ambiguity, where a seller is uncertain about a buyer's true valuation distribution, knowing only that it lies near a reference distribution measured by the Wasserstein metric. Traditional robust optimization (RO) approaches prioritize maximizing worst-case revenue within predefined ambiguity sets, often yielding seller-centric outcomes and reliance on precise set specifications. We propose a robust satisficing (RS) framework aimed at attaining a specified revenue target by minimizing the worst-case shortfall across all potential distributions. Our approach offers a tractable formulation and detailed characterization of optimal mechanisms using randomized pricing strategies. We also assess the out-of-sample efficacy of a simple posted pricing mechanism, finding it particularly effective with lower targets and positively skewed valuations, where smaller valuations have high probability mass. Comparing RO with RS, we find that RS consistently enhances buyer surplus when the reference distribution has an increasing hazard rate and increases out-of-sample seller revenue with positively skewed true valuations. Our analysis indicates that a target-driven RS framework enhances buyer surplus and fairness by offering more opportunities to lower-valuation buyers, potentially boosting overall revenue in scenarios with demand skewed toward these valuations. This approach offers a practical and viable modeling alternative to conventional RO methods, effectively overcoming the challenges of ambiguity set calibration while ensuring broader equitable access for diverse buyers.

math.OC

Service Deployment in the On-Demand Economy: Employees, Contractors, or Both?

The recent advancements in mobile/data technology have fostered a widespread adoption of on-demand or gig service platforms. The increasingly available data and independent contractors have enabled these platforms to design customized services and a cost-efficient workforce to effectively match demand and supply. In practice, a diverse landscape of the workforce has been observed: some rely solely on either employees or contractors, others use a blended workforce with both types of workers. In this paper, we consider a profit-maximizing service provider (SP) that decides to offer a single service or two differentiated services, along with the pricing and staffing of the workforce with employees and/or contractors, to price- and waiting-sensitive customers. Contractors independently determine whether or not to participate in the marketplace based on private reservation rates and per-service wage offered by the SP, while it controls the number of employees who receive per-hour wage. Under a single service, we show that the SP relies on either employees or contractors and identify sufficient and necessary conditions in which one workforce is better than the other. Under the optimal service deployment, we show that the SP offers either a single service relying solely on employees or contractors, or two differentiated services with a hybrid workforce depending on the service value and cost efficiencies of employees and contractors. Our analysis suggests that proliferating services with a blended workforce could improve the SP's profit significantly, and identifies conditions in which this value is significant. Our results provide an in-depth understanding and insightful guidance to on-demand platforms on the design of service differentiation and workforce models.

math.OC