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Kijung Shin

22 accepted papers

2026

Feature-Centric Unsupervised Node Representation Learning Without Homophily Assumption

AAAI 2026technical

Unsupervised node representation learning aims to obtain meaningful node embeddings without relying on node labels. To achieve this, graph convolution, which aggregates information from neighboring nodes, is commonly employed to encode node features and graph topology. However, excessive reliance on

Cited by 0SourcePDFScholar
2026

Rethinking Contrastive Learning for Graph Collaborative Filtering: Limitations and A Simple Remedy

ICML 2026poster

Graph collaborative filtering (GCF) is a dominant paradigm in recommender systems, where contrastive learning (CL) objectives such as the Sampled Softmax (SSM) loss are widely used for optimization. However, it remains unclear how CL interacts with the prediction mechanism of GCF. By unfolding the p…

Cited by 0SourceScholar
2025

DiffIM: Differentiable Influence Minimization with Surrogate Modeling and Continuous Relaxation

AAAI 2025technical

In social networks, people influence each other through social links, which can be represented as propagation among nodes in graphs. Influence minimization (IMIN) is the problem of manipulating the structures of an input graph (e.g., removing edges) to reduce the propagation among nodes. IMIN can re…

2025

Learning to Flow from Generative Pretext Tasks for Neural Architecture Encoding

NeurIPS 2025poster

The performance of a deep learning model on a specific task and dataset depends heavily on its neural architecture, motivating considerable efforts to rapidly and accurately identify architectures suited to the target task and dataset. To achieve this, researchers use machine learning models—typical…

Cited by 0SourceScholar
2025

Mitigating Over-Squashing in Graph Neural Networks by Spectrum-Preserving Sparsification

ICML 2025poster

The message-passing paradigm of Graph Neural Networks often struggles with exchanging information across distant nodes typically due to structural bottlenecks in certain graph regions, a limitation known as over-squashing. To reduce such bottlenecks, graph rewiring, which modifies graph topology, ha…

Cited by 0SourcePDFScholar
2025

RDB2G-Bench: A Comprehensive Benchmark for Automatic Graph Modeling of Relational Databases

NeurIPS 2025poster

Recent advances have demonstrated the effectiveness of graph-based machine learning on relational databases (RDBs) for predictive tasks. Such approaches require transforming RDBs into graphs, a process we refer to as RDB-to-graph modeling, where rows of tables are represented as nodes and foreign-k…

Cited by 0SourcecodeScholar
2025

TimeCAP: Learning to Contextualize, Augment, and Predict Time Series Events with Large Language Model Agents

AAAI 2025technical

Time series data is essential in various applications, including climate modeling, healthcare monitoring, and financial analytics. Understanding the contextual information associated with real-world time series data is often essential for accurate and reliable event predictions. In this paper, we in…

2025

TimeXL: Explainable Multi-modal Time Series Prediction with LLM-in-the-Loop

NeurIPS 2025poster

Time series analysis provides essential insights for real-world system dynamics and informs downstream decision-making, yet most existing methods often overlook the rich contextual signals present in auxiliary modalities. To bridge this gap, we introduce TimeXL, a multi-modal prediction framework th…

Cited by 0SourceScholar
2024

Feature Distribution on Graph Topology Mediates the Effect of Graph Convolution: Homophily Perspective

ICML 2024poster

How would randomly shuffling feature vectors among nodes from the same class affect graph neural networks (GNNs)? The feature shuffle, intuitively, perturbs the dependence between graph topology and features (A-X dependence) for GNNs to learn from. Surprisingly, we observe a consistent and significa…

Cited by 9SourcePDFScholar
2024

FlowerFormer: Empowering Neural Architecture Encoding using a Flow-aware Graph Transformer

CVPR 2024poster

The success of a specific neural network architecture is closely tied to the dataset and task it tackles; there is no one-size-fits-all solution. Thus considerable efforts have been made to quickly and accurately estimate the performances of neural architectures without full training or evaluation f…

2024

HypeBoy: Generative Self-Supervised Representation Learning on Hypergraphs

ICLR 2024poster

Hypergraphs are marked by complex topology, expressing higher-order interactions among multiple nodes with hyperedges, and better capturing the topology is essential for effective representation learning. Recent advances in generative self-supervised learning (SSL) suggest that hypergraph neural net…

2024

Rethinking Reconstruction-based Graph-Level Anomaly Detection: Limitations and a Simple Remedy

NeurIPS 2024poster

Graph autoencoders (Graph-AEs) learn representations of given graphs by aiming to accurately reconstruct them. A notable application of Graph-AEs is graph-level anomaly detection (GLAD), whose objective is to identify graphs with anomalous topological structures and/or node features compared to the…

2024

Sign is Not a Remedy: Multiset-to-Multiset Message Passing for Learning on Heterophilic Graphs

ICML 2024poster

Graph Neural Networks (GNNs) have gained significant attention as a powerful modeling and inference method, especially for homophilic graph-structured data. To empower GNNs in heterophilic graphs, where adjacent nodes exhibit dissimilar labels or features, Signed Message Passing (SMP) has been widel…

2024

Spear and Shield: Adversarial Attacks and Defense Methods for Model-Based Link Prediction on Continuous-Time Dynamic Graphs

AAAI 2024technical

Real-world graphs are dynamic, constantly evolving with new interactions, such as financial transactions in financial networks. Temporal Graph Neural Networks (TGNNs) have been developed to effectively capture the evolving patterns in dynamic graphs. While these models have demonstrated their super…

2024

Tackling Prevalent Conditions in Unsupervised Combinatorial Optimization: Cardinality, Minimum, Covering, and More

ICML 2024poster

Combinatorial optimization (CO) is naturally discrete, making machine-learning techniques based on differentiable optimization inapplicable. Karalias & Loukas (2020) adapted the probabilistic method by Erdős & Spencer (1974), to incorporate CO into differentiable optimization. Their work ignited the…

Cited by 3SourcePDFScholar
2024

VITA: ‘Carefully Chosen and Weighted Less’ Is Better in Medication Recommendation

AAAI 2024technical

We address the medication recommendation problem, which aims to recommend effective medications for a patient's current visit by utilizing information (e.g., diagnoses and procedures) given at the patient's current and past visits. While there exist a number of recommender systems designed for this…

2023

I’m Me, We’re Us, and I’m Us: Tri-directional Contrastive Learning on Hypergraphs

AAAI 2023technical

Although machine learning on hypergraphs has attracted considerable attention, most of the works have focused on (semi-)supervised learning, which may cause heavy labeling costs and poor generalization. Recently, contrastive learning has emerged as a successful unsupervised representation learning m…

2023

Towards Deep Attention in Graph Neural Networks: Problems and Remedies

ICML 2023poster

Graph neural networks (GNNs) learn the representation of graph-structured data, and their expressiveness can be further enhanced by inferring node relations for propagation. Attention-based GNNs infer neighbor importance to manipulate the weight of its propagation. Despite their popularity, the disc…

2022

HashNWalk: Hash and Random Walk Based Anomaly Detection in Hyperedge Streams

IJCAI 2022poster

Sequences of group interactions, such as emails, online discussions, and co-authorships, are ubiquitous; and they are naturally represented as a stream of hyperedges (i.e., sets of nodes). Despite its broad potential applications, anomaly detection in hypergraphs (i.e., sets of hyperedges) has rece…

2022

Meta-Learning for Online Update of Recommender Systems

AAAI 2022technical

Online recommender systems should be always aligned with users' current interest to accurately suggest items that each user would like. Since user interest usually evolves over time, the update strategy should be flexible to quickly catch users' current interest from continuously generated new user-…

2021

PREMERE: Meta-Reweighting via Self-Ensembling for Point-of-Interest Recommendation

AAAI 2021technical

Point-of-interest (POI) recommendation has become an important research topic in these days. The user check-in history used as the input to POI recommendation is very imbalanced and noisy because of sparse and missing check-ins. Although sample reweighting is commonly adopted for addressing this cha…