Owing to their unprecedented comprehension capabilities, large language models (LLMs) have become indispensable components of modern web search engines. From a technical perspective, this integration represents retrieval-augmented generation (RAG), which enhances LLMs by grounding them in external knowledge base. A prevalent technical approach in this context is graph-based RAG (G-RAG). However, current G-RAG methodologies frequently underutilize graph topology, predominantly focusing on low-order structures or pre-computed static communities. This limitation affects their effectiveness in addressing dynamic and complex queries. Thus, we propose DA-RAG, which leverages attributed community search (ACS) to dynamically extract relevant subgraphs based on the queried question. DA-RAG captures high-order graph structures, allowing for the retrieval of self-complementary knowledge. Furthermore, DA-RAG is equipped with a chunk-layer oriented graph index, which facilitates efficient multi-granularity retrieval while significantly reducing both computational and economic costs. We evaluate DA-RAG on multiple datasets, demonstrating that it outperforms existing RAG methods by up to 40% in head-to-head comparisons across four metrics while reducing index construction time and token overhead by up to 37% and 41%, respectively.

Traffic Signal Control plays a vital role in modern traffic management. However, most existing methods focus exclusively on vehicle flow, neglecting the critical role of pedestrians, leading to suboptimal performance in intersections with mixed vehicle-pedestrian traffic. Pedestrian behavior presents unique challenges due to its irregularity and flexibility, such as non-lane-based movements and uncertain crossing directions, which cannot be modeled by existing methods. To address this limitation, we propose VPLight, a comprehensive framework designed to manage bothVehicle andPedestrian dynamics in traffic signal control. Specifically, we first design the Pedestrian Feature Extractor to capture the spatiotemporal dynamics of pedestrian movement, offering a robust representation of their irregular patterns. Subsequently, to coordinate traffic signal control at multiple intersections, we develop a novel communication approach called V-Comm to enable effective integration among intersections. Extensive experiments show that VPLight outperforms state-of-the-art baselines with significant margins (up to +44.04%). Our results demonstrate that VPLight can remarkably address the challenges of mixed vehicle-pedestrian traffic control and enhance the overall traffic flow efficiency across the road network.

A modern service model known as the “hub-oriented” model has emerged with the development of mobility services. This model allows users to request vehicles from multiple companies (agents) simultaneously through a unified entry (a ‘hub’). In contrast to conventional services, the “hub-oriented” model emphasizes pricing competition. To address this scenario, an agent should consider its competitors when developing its pricing strategy. In this paper, we introduce DRLPG, a mixed opponent-aware pricing method, which consists of two main components: the two-stage guarantor and the end-to-end deep reinforcement learning (DRL) module, as well as interaction mechanisms. In the guarantor, we design a prediction-decision framework. Specifically, we propose a new objective function for the spatiotemporal neural network in the prediction stage and utilize a traditional reinforcement learning method in the decision stage, respectively. In the end-to-end DRL framework, we explore the adoption of conventional DRL in the “hub-oriented” scenario. Finally, a meta-decider and an experience-sharing mechanism are proposed to combine both methods and leverage their advantages. We conduct extensive experiments on real data, and DRLPG achieves an average improvement of 99.9% and 61.1% in the peak and low peak periods, respectively. Our results demonstrate the effectiveness of our approach compared to the baseline.

Hub-oriented mobility services have gained great developments in recent years, enabling riders to simultaneously call vehicles from multiple mobility-supply companies (agents) on a single APP (which we call "hub"). Competing with others on such a hub, to obtain an order, an agent company first needs to get admitted by the requester, which is in turn affected by its quotation. The quotation needs to be attractively low compared to those of the opposing agents. Thus, an opponent-aware pricing strategy is needed for an agent to play well in the hub scenario, which is rarely discussed in existing works. To address the aforementioned issue, in this work, we first propose a quotation prediction model, which employs a neural network with a customized loss function to predict the opponents’ quotations. Based on the predictions, we then propose multi-arm bandit based methods to decide a proper quotation for the agent, in order to obtain orders while retaining profits. We finally conduct extensive experiments on real data, where the quotation-determining method integrated with the prediction model has achieved a remarkable profit improvement up to 85.5% compared to baseline methods, demonstrating their effectiveness.