Boyang Li

Spatial crowdsourcing platforms have become indispensable in addressing the evolving needs of modern society. These platforms facilitate essential services such as ride-sharing, on-demand food delivery, and efficient parcel distribution. However, the uneven distribution of workers and requests under a single-platform setting may lead to the loss of tasks. To address this issue, we introduce the Cross Online Matching (COM) problem, which facilitates collaboration among multiple platforms. We first propose DemCOM and RamCOM, which adopt deterministic greedy and randomized trade-off strategies, respectively. Furthermore, we develop a Utility-Distribution Aware Cooperative Online Matching (UDACOM) algorithm that leverages supply-demand relationships to optimize decision-making. Theoretical analysis confirms the competitive ratios of our algorithms. Validated on both real and synthetic datasets, our approach significantly outperforms state-of-the-art methods, achieving a 5% increase in total revenue and a 3% improvement in the successful matching rate.

In recent years, the task of knowledge graph completion has attracted significant attention from researchers. In practical scenarios, multi-source knowledge graph completion is quite common. Federated knowledge graph embedding enables joint learning across multiple knowledge graphs while ensuring data privacy and security. Generally, each data source has a different data distribution. They may exhibit various connections, such as combinatorial, hierarchical, and symmetric/asymmetric connections. Existing federated knowledge graph models overlook the data heterogeneity of knowledge graphs from different sources, using a unified scoring function to assess the quality of the generated embedding vectors from different clients. This limitation affects the quality of knowledge graph embeddings generated by each client. Therefore, this paper proposes a federated knowledge graph embedding framework based on the diffusion model. On the client side, we employ diffusion model to learn knowledge graph embeddings. We utilize the diffusion model's forward noise-adding process to learn the knowledge graph's distribution. We then use the reverse denoising process to generate knowledge embeddings directly. Additionally, we employ knowledge distillation during client model training to address the drift between local optimization and global convergence. Since the original data cannot leave the local environment in federated learning, we adopt a framework that shares diffusion models for federated knowledge graph completion. Extensive experiments demonstrate that our model significantly outperforms existing state-of-the-art methods in three benchmark datasets.

Online spatial crowdsourcing platforms provide popular O2O services in people's daily. Users submit real-time tasks through the Internet and require the platform to immediately assign workers to serve them. However, the imbalance distribution of tasks and workers leads to the rejection of some tasks, which reduces the profit of the platform. In this paper, we propose that similar platforms can form an alliance to make full use of the global service supply through cooperation. We name the problem as G lobal T ask A ssignment (GTA), in which platforms are allowed to hire idle workers from other platforms to improve the profit of all the platforms together. Different from relevant works, the decision-makers in GTA are platforms rather than individual workers, which can better assign workers in all platforms and improve the overall profit. We design an auction-based incentive mechanism (AIM), to motivate platforms to rent idle workers to other platforms so that increase their own profit. Based on the mechanism, we propose a greedy-based assignment algorithm (BaseGTA), in which platforms greedily maximizes their current profit. We further propose a prediction-based assignment algorithm (ImpGTA), in which platforms make decisions based on the spatial-temporal distribution in the future time. Experimental results show that platforms using our algorithms can achieve higher profit than the existing studies.