Session-based Social Recommendation (SSR) enhances item recommendations by incorporating both session interactions and social network data. Despite recent progress, existing SSR methods-primarily based on Graph Neural Networks-are highly susceptible to session noise (irrelevant or unintentional interactions) and social noise (misleading signals from connected users). Prior denoising strategies often rely on heuristic resampling or reweighting techniques, which lack generalizability and robustness across diverse datasets. In this work, we explore a novel direction by introducing diffusion models for denoising in SSR. However, applying diffusion to SSR presents unique challenges due to heterogeneous data modalities, incompatible noise patterns, and the absence of semantic guidance during the reverse process. To overcome these challenges, we propose D3MRec, a Dual Denoising Diffusion Model specifically designed for SSR. D3MRec employs a dual-branch architecture that independently models session sequences and social graphs, applying denoising diffusion in their respective hidden representation spaces. This decoupled design preserves the structural integrity of each modality while enabling modality-specific denoising. Moreover, we introduce cross-modal guidance by leveraging collaborative signals from the other branch during the reverse diffusion process, enhancing alignment between session intents and social preferences. The dual denoising processes not only mitigate noise within each modality but also serve as mutual priors, facilitating robust and consistent representation learning across modalities. Extensive experiments on multiple benchmarks show that D3MRec significantly outperforms state-of-the-art models, particularly under noisy conditions, demonstrating its effectiveness and robustness.

Session-based Social Recommendation (SSR) aims to improve next-item prediction by combining a user’s session activities with insights from their social networks. However, the brevity of sessions makes SSR models prone to noise, and many methods rely on complex Deep Neural Networks (DNNs), which often lead to long training times. To address these challenges, we introduce a novel SSR approach that leverages autocorrelation, a concept from stochastic processes, to model sequential dependencies more effectively. By applying Fast Fourier Transforms (FFT) to compute autocorrelation and integrating this with multi-head attention mechanisms, our method captures temporal patterns within session data more accurately. Extensive experiments on two public datasets demonstrate that our method outperforms existing state-of-the-art SSR models in both accuracy and efficiency. Our code is available at https://github.com/LUUUUUUZ/MACNet.

With the rapid growth of Massive Open Online Courses (MOOCs), it is expensive and time-consuming to extract high-quality knowledgeable concepts taught in the course by human effort to help learners grasp the essence of the course.In this paper, we propose to automatically extract course concepts using distant supervision to eliminate the heavy work of human annotations, which generates labels by matching them with an easily accessed dictionary.However, this matching process suffers from severe noisy and incomplete annotations because of the limited dictionary and diverse MOOCs.To tackle these challenges, we present a novel three-stage framework DS-MOCE, which leverages the power of pretrained language models explicitly and implicitly and employs discipline-embedding models with a self-train strategy based on label generation refinement across different domains.We also provide an expert-labeled dataset spanning 20 academic disciplines.Experimental results demonstrate the superiority of DS-MOCE over the state-of-the-art distantly supervised methods (with 7% absolute F1 score improvement).Code and data are now available at https: //github.com/THU-KEG/MOOC-NER.

Student modeling, the task of inferring a student's learning characteristics through their interactions with coursework, is a fundamental issue in intelligent education. Although the recent attempts from knowledge tracing and cognitive diagnosis propose several promising directions for improving the usability and effectiveness of current models, the existing public datasets are still insufficient to meet the need for these potential solutions due to their ignorance of complete exercising contexts, fine-grained concepts, and cognitive labels. In this paper, we present MoocRadar, a fine-grained, multi-aspect knowledge repository consisting of 2,513 exercise questions, 5,600 knowledge concepts, and over 12 million behavioral records. Specifically, we propose a framework to guarantee a high-quality and comprehensive annotation of fine-grained concepts and cognitive labels. The statistical and experimental results indicate that our dataset provides the basis for the future improvements of existing methods. Moreover, to support the convenient usage for researchers, we release a set of tools for data querying, model adaption, and even the extension of our repository, which are now available at https://github.com/THU-KEG/MOOC-Radar.