A Large Language Model Enhanced Sequential Recommender for Joint Video and Comment Recommendation

In online video platforms, reading or writing comments on interesting videos has become an essential part of the video watching experience. However, existing video recommender systems mainly model users' interaction behaviors with videos, lacking consideration of comments in user behavior modeling. In this paper, we propose a novel recommendation approach called LSVCR by leveraging user interaction histories with both videos and comments, so as to jointly conduct personalized video and comment recommendation. Specifically, our approach consists of two key components, namely sequential recommendation (SR) model and supplemental large language model (LLM) recommender. The SR model serves as the primary recommendation backbone (retained in deployment) of our approach, allowing for efficient user preference modeling. Meanwhile, we leverage the LLM recommender as a supplemental component (discarded in deployment) to better capture underlying user preferences from heterogeneous interaction behaviors. In order to integrate the merits of the SR model and the supplemental LLM recommender, we design a twostage training paradigm. The first stage is personalized preference alignment, which aims to align the preference representations from both components, thereby enhancing the semantics of the SR model. The second stage is recommendation-oriented fine-tuning, in which the alignment-enhanced SR model is fine-tuned according to specific objectives. Extensive experiments in both video and comment recommendation tasks demonstrate the effectiveness of LSVCR. Additionally, online A/B testing on the KuaiShou platform verifies the actual benefits brought by our approach. In particular, we achieve a significant overall gain of 4.13% in comment watch time.

A deep reinforcement learning approach for real-time demand-responsive railway rescheduling to mitigate station overcrowding using mobile data

Real-time railway rescheduling is a timely and flexible technique to automatically alter the operation schedule in response to time-varying conditions. Current research lacks data-driven approaches that capture real-time passenger mobility during railway disruptions, relying mostly on OD-based data and model-based methods for estimating demands of trains. Meanwhile, the schedule-updating principles for a long-term disruption overlook the uneven distribution of demand over time. To fill this gap, this paper proposes a demand-responsive approach by inferring real-world passenger mobility from mobile data (MD) to facilitate real-time rescheduling. Unlike network-level approaches, this paper focuses on a heavy-demand station upstream of the disrupted area. The objective is to reschedule all trains on multiple routes passing through this target station, which have been affected by a severe emergency event such as a natural disaster. Particular attention should be given to avoiding the accumulation of overcrowded passengers at this station, to prevent additional accidents arising from overcrowding. This research addresses the challenges associated with this scenario, including the dynamics of arriving and leaving of passengers, station overcrowding, rolling stock shortage, open-ended disruption duration, integrated rescheduling on multiple routes, and delays due to detours. A deep reinforcement learning (DRL) framework is proposed to determine the optimal rescheduled timetable, route stops, and rolling stock allocation, while considering real-time demand satisfaction, station overcrowding, train capacity utilization, and headway safety.