OpenRaiser/Intern-Atlas huggingface dataset:
PyG-SSL: A Graph Self-Supervised Learning Toolkit
Authors: Lecheng Zheng, Baoyu Jing, Zihao Li, Zhichen Zeng, Tianxin Wei, Mengting Ai, Xinrui He, Lihui Liu, Dongqi Fu, Jiaxuan You, Hanghang Tong, Jingrui He
Venue: CIKM
Year: 2025

Graph Self-Supervised Learning (SSL) has emerged as a pivotal area of research in recent years. By engaging in pretext tasks to learn the intricate topological structures and properties of graphs using unlabeled data, these graph SSL models achieve enhanced performance, improved generalization, and heightened robustness. Despite the remarkable achievements of these graph SSL methods, their current implementation poses significant challenges for beginners and practitioners due to the complex nature of graph structures, inconsistent evaluation metrics, and concerns regarding reproducibility hinder further progress in this field. Recognizing the growing interest within the research community, there is an urgent need for a comprehensive, beginner-friendly, and accessible toolkit consisting of the most representative graph SSL algorithms. To address these challenges, we present a Graph SSL toolkit named PyG-SSL, which is built upon PyTorch and is compatible with various deep learning and scientific computing backends. Within the toolkit, we offer a unified framework encompassing dataset loading, hyper-parameter configuration, model training, and comprehensive performance evaluation for diverse downstream tasks. Moreover, we provide beginner-friendly tutorials and the best hyper-parameters of each graph SSL algorithm on different graph datasets, facilitating the reproduction of results. The GitHub repository of the library is https://github.com/iDEA-iSAIL-Lab-UIUC/pyg-ssl.
Modeling Edge-Specific Node Features through Co-Representation Neural Hypergraph Diffusion
Authors: Yijia Zheng, Marcel Worring
Venue: CIKM
Year: 2025

Hypergraphs are widely being employed to represent complex higher-order relations in real-world applications. Most existing research on hypergraph learning focuses on node-level or edge-level tasks. A practically relevant and more challenging task, edge-dependent node classification (ENC), is still under-explored. In ENC, a node can have different labels across different hyperedges, which requires the modeling of node features unique to each hyperedge. The state-of-the-art ENC solution, WHATsNet, only outputs single node and edge representations, leading to the limitations of entangled edge-specific features and non-adaptive representation sizes when applied to ENC. Additionally, WHATsNet suffers from the common oversmoothing issue in most HGNNs. To address these limitations, we propose CoNHD, a novel HGNN architecture specifically designed to model edge-specific features for ENC. Instead of learning separate representations for nodes and edges, CoNHD reformulates within-edge and within-node interactions as a hypergraph diffusion process over node-edge co-representations. We develop a neural implementation of the proposed diffusion process, leveraging equivariant networks as diffusion operators to effectively learn the diffusion dynamics from data. Extensive experiments demonstrate that CoNHD achieves the best performance across all benchmark ENC datasets and several downstream tasks without sacrificing efficiency. Our implementation is available at https://github.com/zhengyijia/CoNHD.
Non-autoregressive Generative Auction with Global Externalities for Online Advertising
Authors: Zuowu Zheng, Ze Wang, Fan Yang, Wenqing Ye, Weihua Huang, Wenqiang He, Teng Zhang, Xingxing Wang
Venue: CIKM
Year: 2025

Online advertising auctions play a critical role in internet commerce, requiring mechanisms that maximize revenue while ensuring incentive compatibility, user experiences, and real-time efficiency. Existing learning-based auction frameworks advance contextual modeling by considering intra-list dependencies among ads, but still face challenges of insufficient global externality modeling and inefficiencies due to sequential processing. In this paper, we propose the Non-autoregressive Generative Auction with global externalities (NGA), a novel end-to-end auction framework for industrial online advertising. NGA explicitly models global externalities by jointly encoding dependencies among ads and the influence of neighboring organic content. To achieve real-time efficiency, NGA employs a non-autoregressive, constraint-based decoding mechanism and a parallel multi-tower evaluator that unifies list-wise reward and payment computation. Extensive offline experiments and large-scale online A/B tests on commercial advertising platforms demonstrate that NGA achieves superior performance in both effectiveness and efficiency compared to the state-of-the-art baselines.
MI4Rec: Pretrained Language Model based Cold-Start Recommendation with Meta-Item Embeddings
Authors: Zaiyi Zheng, Yaochen Zhu, Haochen Liu, Mingxuan Ju, Tong Zhao, Neil Shah, Jundong Li
Venue: CIKM
Year: 2025

Recently, pretrained large language models (LLMs) have been widely adopted in recommendation systems to leverage their textual understanding and reasoning abilities to model user behaviors and suggest future items. A key challenge in this setting is that items on most platforms are not included in the LLM's training data. Therefore, existing methods often fine-tune LLMs by introducing auxiliary item tokens to capture item semantics. However, in real-world applications such as e-commerce and short video platforms, the item space evolves rapidly, which gives rise to a cold-start setting, where many newly introduced items receive little or even no user engagement. This poses challenges in both learning accurate item token embeddings and generalizing efficiently to accommodate the continual influx of new items. In this work, we propose a novel meta-item token learning strategy to address both these challenges simultaneously. Specifically, we introduce MI4Rec, an LLM-based approach for recommendation that uses just a few learnable meta-item tokens and an LLM encoder to dynamically aggregate meta-items based on item content. We show that this paradigm allows highly efficient and accurate learning in such challenging settings. Extensive experiments on Yelp and Amazon reviews datasets demonstrate the effectiveness of MI4Rec in both warm-start and cold-start recommendations. Notably, MI4Rec achieves an average performance improvement of 20.4% in Recall and NDCG compared to the best-performing baselines. The implementation of MI4Rec is available at https://github.com/zhengzaiyi/MI4Rec
Adaptive Spline Networks in the Kolmogorov-Arnold Framework: Knot Analysis and Stability Enhancement
Authors: Liangwei Nathan Zheng, Wei Emma Zhang, Lin Yue, Miao Xu, Olaf Maennel, Weitong Chen
Venue: CIKM
Year: 2025

Kolmogorov-Arnold Neural Networks (KANs) have recently attracted significant attention in the machine learning community. However, their practical implementation often faces challenges such as poor training stability and a large number of trainable parameters. Moreover, the behavior of learnable activation functions based on B-splines remains insufficiently understood. In this work, we analyze KANs through the lens of spline knot behavior and derive lower and upper bounds on the number of knots in B-spline-based KANs. To address the existing limitations, we propose a novel KAN-based approach, which improves upon the original KAN by reducing the number of trainable parameters to match the scale of standard Multi-Layer Perceptrons (MLPs), while enhancing overall performance. Additionally, we introduce a new training strategy that enforces C2 continuity in the learnable splines, leading to smoother activation functions and improved training stability via range expansion. We evaluate our method across eight diverse datasets encompassing image, text, time series, multimodal, and function approximation tasks. The promising results demonstrate the feasibility of KAN-based architectures and the effectiveness of our proposed enhancements. The proposed method implementation is released in https://github.com/IcurasLW/FR-KAN.git
EvoFormer: Learning Dynamic Graph-Level Representations with Structural and Temporal Bias Correction
Authors: Haodi Zhong, Liuxin Zou, Di Wang, Bo Wan, Zhenxing Niu, Quan Wang
Venue: CIKM
Year: 2025

Dynamic graph-level embedding aims to capture structural evolution in networks, which is essential for modeling real-world scenarios. However, existing methods face two critical yet under-explored issues: Structural Visit Bias, where random walk sampling disproportionately emphasizes high-degree nodes, leading to redundant and noisy structural representations; and Abrupt Evolution Blindness, the failure to effectively detect sudden structural changes due to rigid or overly simplistic temporal modeling strategies, resulting in inconsistent temporal embeddings. To overcome these challenges, we propose EvoFormer, an evolution-aware Transformer framework tailored for dynamic graph-level representation learning. To mitigate Structural Visit Bias, EvoFormer introduces a Structure-Aware Transformer Module that incorporates positional encoding based on node structural roles, allowing the model to globally differentiate and accurately represent node structures. To overcome Abrupt Evolution Blindness, EvoFormer employs an Evolution-Sensitive Temporal Module, which explicitly models temporal evolution through a sequential three-step strategy: (I) Random Walk Timestamp Classification, generating initial timestamp-aware graph-level embeddings; (II) Graph-Level Temporal Segmentation, partitioning the graph stream into segments reflecting structurally coherent periods; and (III) Segment-Aware Temporal Self-Attention combined with an Edge Evolution Prediction task, enabling the model to precisely capture segment boundaries and perceive structural evolution trends, effectively adapting to rapid temporal shifts. Extensive evaluations on five benchmark datasets confirm that EvoFormer achieves state-of-the-art performance in graph similarity ranking, temporal anomaly detection, and temporal segmentation tasks, validating its effectiveness in correcting structural and temporal biases. Code is available at https://github.com/zlx0823/EvoFormerCode.
Budget and Frequency Controlled Cost-Aware Model Extraction Attack on Sequential Recommenders
Authors: Lei Zhou, Min Gao, Zongwei Wang, Yibing Bai
Venue: CIKM
Year: 2025

Sequential recommenders are integral to many applications yet remain vulnerable to model extraction attacks, in which adversaries can recover information about the deployed model by issuing queries to a black-box without internal access. From the attacker's perspective, existing studies impose a fixed and limited query budget but overlook optimal allocation, resulting in redundant or low-value requests. Furthermore, the scarce data obtained through these costly queries is typically handled by crude random sampling, resulting in low diversity and information coverage with actual data. In this paper, we propose a novel approach, named Budget and Frequency Controlled Cost-Aware Model Extraction Attack (BECOME), for extracting black-box sequential recommenders, which extends the standard extraction framework with two cost-aware innovations: Feedback-Driven Dynamic Budgeting periodically evaluates the victim model to refine query allocation and steer sequence generation adaptively. Rank-Aware Frequency Controlling integrates frequency constraints with ranking guidance in the next-item sampler to select high-value items and broaden information coverage. Experiments on public datasets and representative sequential recommender architectures demonstrate that our method achieves superior extraction performance. Our code is released at https://github.com/Loche2/BECOME.
Toward Robust Machine Learning under Diverse Incomplete Data Mechanisms in Real-World Applications
Authors: Youran Zhou
Venue: CIKM
Year: 2025

Incomplete data is a pervasive challenge across a wide range of data types, including tabular, sensor, time-series, image, and textual data. Its presence stems from various real-world factors and gives rise to different missingness mechanisms. While much of the existing research focuses on the Missing Completely At Random (MCAR) assumption, the more complex and realistic mechanisms-Missing At Random (MAR) and Missing Not At Random (MNAR)-remain relatively underexplored despite their prevalence and impact. This PhD project aims to systematically investigate the challenges posed by diverse Incomplete data mechanisms and to develop robust machine learning methods that can perform reliably across MCAR, MAR, and MNAR scenarios. The research spans multiple data modalities and focuses on improving both the theoretical understanding and practical handling of incomplete data. By addressing mechanism-specific imputation challenges and proposing broadly applicable solutions, this work contributes to building more resilient and trustworthy data-driven systems in real-world settings.
MissDDIM: Deterministic and Efficient Conditional Diffusion for Tabular Data Imputation
Authors: Youran Zhou, Mohamed Reda Bouadjenek, Sunil Aryal
Venue: CIKM
Year: 2025

Diffusion models have recently emerged as powerful tools for missing data imputation by modeling the joint distribution of observed and unobserved variables. However, existing methods, typically based on stochastic denoising diffusion probabilistic models (DDPMs), suffer from high inference latency and variable outputs, limiting their applicability in real-world tabular settings. To address these deficiencies, we present in this paper MissDDIM, a conditional diffusion framework that adapts Denoising Diffusion Implicit Models (DDIM) for tabular imputation. While stochastic sampling enables diverse completions, it also introduces output variability that complicates downstream processing. MissDDIM replaces this with a deterministic, non-Markovian sampling path, yielding faster and more consistent imputations. To better leverage incomplete inputs during training, we introduce a self-masking strategy that dynamically constructs imputation targets from observed features-enabling robust conditioning without requiring fully observed data. Experiments on five benchmark datasets demonstrate that MissDDIM matches or exceeds the accuracy of state-of-the-art diffusion models, while significantly improving inference speed and stability. These results highlight the practical value of deterministic diffusion for real-world imputation tasks.
Enhancing Dual-Target Cross-Domain Recommendation via Similar User Bridging
Authors: Qi Zhou, Xi Chen, Chuyu Fang, Jianji Wang, Chuan Qin, Fuzhen Zhuang
Venue: CIKM
Year: 2025

Dual-target cross-domain recommendation aims to mitigate data sparsity and enables mutual enhancement via bidirectional knowledge transfer. Most existing methods rely on overlapping users to build cross-domain connections. However, in many real-world scenarios, overlapping data is extremely limited-or even entirely absent-significantly diminishing the effectiveness of these methods. To address this challenge, we propose SUBCDR, a novel framework that leverages large language models (LLMs) to bridge similar users across domains, thereby enhancing dual-target cross-domain recommendation. Specifically, we introduce a Multi-Interests-Aware Prompt Learning mechanism that enables LLMs to generate comprehensive user profiles, disentangling domain-invariant interest points while capturing fine-grained preferences. Then, we construct intra-domain bipartite graphs from user-item interactions and an inter-domain heterogeneous graph that links similar users across domains. Subsequently, to facilitate effective knowledge transfer, we employ Graph Convolutional Networks (GCNs) for intra-domain relationship modeling and design an Inter-domain Hierarchical Attention Network (InterHAN) to facilitate inter-domain knowledge transfer through similar users, learning both shared and specific user representations. Extensive experiments on seven public datasets demonstrate that SUBCDR outperforms state-of-the-art cross-domain recommendation algorithms and single-domain recommendation methods. Our code is publicly available at https://github.com/97z/SUBCDR.git.
BALM-TSF: Balanced Multimodal Alignment for LLM-Based Time Series Forecasting
Authors: Shiqiao Zhou, Holger Schöner, Huanbo Lyu, Edouard Fouché, Shuo Wang
Venue: CIKM
Year: 2025

Time series forecasting is a long-standing and highly challenging research topic. Recently, driven by the rise of large language models (LLMs), research has increasingly shifted from purely time series methods toward harnessing textual modalities to enhance forecasting performance. However, the vast discrepancy between text and temporal data often leads current multimodal architectures to over-emphasise one modality while neglecting the other, resulting in information loss that harms forecasting performance. To address this modality imbalance, we introduce BALM-TSF (Balanced Multimodal Alignment for LLM-Based Time Series Forecasting), a lightweight time series forecasting framework that maintains balance between the two modalities. Specifically, raw time series are processed by the time series encoder, while descriptive statistics of raw time series are fed to an LLM with learnable prompt, producing compact textual embeddings. To ensure balanced cross-modal context alignment of time series and textual embeddings, a simple yet effective scaling strategy combined with a contrastive objective then maps these textual embeddings into the latent space of the time series embeddings. Finally, the aligned textual semantic embeddings and time series embeddings are together integrated for forecasting. Extensive experiments on standard benchmarks show that, with minimal trainable parameters, BALM-TSF achieves state-of-the-art performance in both long-term and few-shot forecasting, confirming its ability to harness complementary information from text and time series. Code is available at https://github.com/ShiqiaoZhou/BALM-TSF.
FinCast: A Foundation Model for Financial Time-Series Forecasting
Authors: Zhuohang Zhu, Haodong Chen, Qiang Qu, Vera Chung
Venue: CIKM
Year: 2025

Financial time-series forecasting is critical for maintaining economic stability, guiding informed policymaking, and promoting sustainable investment practices. However, it remains challenging due to various underlying pattern shifts. These shifts arise primarily from three sources: temporal non-stationarity (distribution changes over time), multi-domain diversity (distinct patterns across financial domains such as stocks, commodities, and futures), and varying temporal resolutions (patterns differing across per-second, hourly, daily, or weekly indicators). While recent deep learning methods attempt to address these complexities, they frequently suffer from overfitting and typically require extensive domain-specific fine-tuning. To overcome these limitations, we introduce FinCast, the first foundation model specifically designed for financial time-series forecasting, trained on large-scale financial datasets. Remarkably, FinCast exhibits robust zero-shot performance, effectively capturing diverse patterns without domain-specific fine-tuning. Comprehensive empirical and qualitative evaluations demonstrate that FinCast surpasses existing state-of-the-art methods, highlighting its strong generalization capabilities.
DebiasedKGE: Towards Mitigating Spurious Forgetting in Continual Knowledge Graph Embedding
Authors: Junlin Zhu, Bo Fu, Guiduo Duan
Venue: CIKM
Year: 2025

To maintain an effective memory of old knowledge in a dynamically growing knowledge environment, continual knowledge graph embedding (CKGE) focuses on alleviating catastrophic forgetting. However, existing CKGE methods still suffer substantial performance degradation in dynamic knowledge graphs (DKG). We have found this challenge is mainly posed by spurious forgetting, a previously overlooked phenomenon that arises from the inherent interference effects in the continual learning (CL) process. In this paper, we deeply explore spurious forgetting in CKGE. First, we reveal two primary causes of spurious forgetting, knowledge interference and knowledge misalignment, and how to affect knowledge biasing within dynamic learning scenarios. Second, to fill this research gap, we propose a robust and efficient CKGE method (DebiasedKGE) for mitigating spurious forgetting. Specifically, to alleviate knowledge interference, we propose a mutual information-guided disentangled learning mechanism, which identifies latent features of different knowledge types and learns independent semantic representations for each, thereby reducing interference in knowledge embedding. Furthermore, to mitigate the deviation of new knowledge from previously learned knowledge, we design a dual-view regularized knowledge alignment mechanism that jointly constrains both the magnitude and direction of embedding transitions. Finally, we evaluate DebiasedKGE on four public CKGE datasets and two additional datasets constructed to contain knowledge perturbations of different dimensions. The results show that DebiasedKGE effectively alleviates spurious forgetting and achieves significant performance improvements. Our codes and datasets are available at https://anonymous.4open.science/r/DebiasedKGE.
RankMixer: Scaling Up Ranking Models in Industrial Recommenders
Authors: Jie Zhu, Zhifang Fan, Xiaoxie Zhu, Yuchen Jiang, Hangyu Wang, Xintian Han, Haoran Ding, Xinmin Wang, Wenlin Zhao, Zhen Gong, Huizhi Yang, Zheng Chai, Zhe Chen, Yuchao Zheng, Qiwei Chen, Feng Zhang, Xun Zhou, Peng Xu, Xiao Yang, Di Wu, Zuotao Liu
Venue: CIKM
Year: 2025

Recent progress on large language models (LLMs) has spurred interest in scaling up recommendation systems, yet two practical obstacles remain. First, training and serving cost on industrial Recommenders must respect strict latency bounds and high QPS demands. Second, most human-designed feature-crossing modules in ranking models were inherited from the CPU era and fail to exploit modern GPUs, resulting in low Model Flops Utilization (MFU) and poor scalability. We introduce RankMixer, a hardware-aware model design tailored towards a unified and scalable feature-interaction architecture. RankMixer retains the transformer's high parallelism while replacing quadratic self-attention with multi-head token mixing module for higher efficiency. Besides, RankMixer maintains both the modeling for distinct feature subspaces and cross-feature-space interactions with Per-token FFNs. We further extend it to one billion parameters with a Sparse-MoE variant for higher ROI. A dynamic routing strategy is adapted to address the inadequacy and imbalance of experts training. Experiments show RankMixer's superior scaling abilities on a trillion-scale production dataset. By replacing previously diverse handcrafted low-MFU modules with RankMixer, we boost the model MFU from 4.5% to 45%, and scale our online ranking model parameters by two orders of magnitude while maintaining roughly the same inference latency. We verify RankMixer's universality with online A/B tests across two core application scenarios (Recommendation and Advertisement). Finally, we launch 1B Dense-Parameters RankMixer for full traffic serving without increasing the serving cost, which improves user active days by 0.3% and total in-app usage duration by 1.08%.