VLDB 2026 Research / reviewers in the wild / expert
Namyong Park 0001
dblp:116/9404-1
· DBLP profile ↗
31ranked-venue papers
13as first author
19since 2021 · last 2026
0000-0002-3344-2361ORCID · verified
Domains — the database's venue-derived domains; a paper can count in several
Artificial intelligence and machine learning · 20 · 9 first-author · 13 since 2021Databases, data management, data science and information retrieval · 17 · 9 first-author · 8 since 2021Graphics, computer vision, multimedia, augmented reality and games · 2 · 2 since 2021Applied, interdisciplinary, general and emerging computing · 2 · 1 first-author · 2 since 2021Systems, architecture and hardware · 1
| Year | Publication | Venue | Position |
|---|---|---|---|
| 2026 | Reasoning Graph-Structured Question Answering: Datasets and Insights from LLM Benchmarking
Khin S. Yone, Devasha Trivedi, Anish Pahilajani, Jincen Shuai, Samyak Rajesh Jain, Ryan Rossi, Nesreen K. Ahmed, Franck Dernoncourt, Yu Wang 0160, Namyong Park 0001 |
LREC | 10 |
| 2025 | From Selection to Generation: A Survey of LLM-based Active LearningabstractYu Xia, Subhojyoti Mukherjee, Zhouhang Xie, Junda Wu, Xintong Li, Ryan Aponte, Hanjia Lyu, Joe Barrow, Hongjie Chen, Franck Dernoncourt, Branislav Kveton, Tong Yu, Ruiyi Zhang, Jiuxiang Gu, Nesreen K. Ahmed, Yu Wang, Xiang Chen, Hanieh Deilamsalehy, Sungchul Kim, Zhengmian Hu, Yue Zhao, Nedim Lipka, Seunghyun Yoon, Ting-Hao Kenneth Huang, Zichao Wang, Puneet Mathur, Soumyabrata Pal, Koyel Mukherjee, Zhehao Zhang, Namyong Park, Thien Huu Nguyen, Jiebo Luo, Ryan A. Rossi, Julian McAuley. Proceedings of the 63rd Annual Meeting of the Association for Computational Linguistics (Volume 1: Long Papers). 2025. Yu Xia 0007, Subhojyoti Mukherjee, Zhouhang Xie, Junda Wu, Xintong Li 0001, Ryan Aponte, Hanjia Lyu, Joe Barrow, Hongjie Chen 0003, Franck Dernoncourt, Branislav Kveton, Tong Yu 0001, Ruiyi Zhang 0002, Jiuxiang Gu, Nesreen K. Ahmed, Yu Wang 0160, Xiang Chen 0010, Hanieh Deilamsalehy, Sungchul Kim, Zhengmian Hu, Yue Zhao 0016, Nedim Lipka, Seunghyun Yoon 0002, Ting-Hao 'Kenneth' Huang, Zichao Wang 0001, Puneet Mathur, Soumyabrata Pal, Koyel Mukherjee 0001, Zhehao Zhang 0001, Namyong Park 0001, Thien Huu Nguyen, Jiebo Luo 0001, Ryan Rossi, Julian J. McAuley |
ACL (1) | 30 |
| 2025 | A Large-scale Training Paradigm for Graph Generative ModelsabstractLarge Generative Models (LGMs) such as GPT, Stable Diffusion, Sora, and Suno are trained on a huge amount of texts, images, videos, and audio that are extremely diverse from numerous domains. This large-scale training paradigm on diverse well-curated data enhances the creativity and diversity of the generated content. However, all previous graph-generative models (e.g., GraphRNN, MDVAE, MoFlow, GDSS, and DiGress) have been trained only on one dataset each time, which cannot replicate the revolutionary success achieved by LGMs in other fields. To remedy this crucial gap, we propose a large-scale training paradigm that uses a large corpus of graphs (over 5000 graphs) from 13 domains, leading to the development of large graph generative models (LGGMs). We empirically demonstrate that the pre-trained LGGMs have superior zero-shot generative capability to existing graph generative models. Furthermore, our pre-trained LGGMs can be easily fine-tuned with graphs from target domains and demonstrate even better performance than those directly trained from scratch, behaving as a solid starting point for real-world customization. Inspired by Stable Diffusion, we further equip LGGMs with the Text-to-Graph generation capability, such as providing the description of the network name and domain (i.e., "The power-1138-bus graph represents a network of buses in a power distribution system.") and network statistics (i.e., "The graph has a low average degree, suitable for modeling social media interactions."). This Text-to-Graph capability integrates the extensive world knowledge in the underlying language model, offering users fine-grained control of the generated graphs. We release the code, the model checkpoint, and the datasets at https://github.com/KINDLab-Fly/LGGM. Yu Wang 0160, Ryan Rossi, Namyong Park 0001, Huiyuan Chen, Nesreen K. Ahmed, Puja Trivedi, Franck Dernoncourt, Danai Koutra, Tyler Derr |
ICLR | 3 |
| 2025 | Personalized Graph-Based Retrieval for Large Language Models
Steven Au, Cameron J. Dimacali, Ojasmitha Pedirappagari, Namyong Park 0001, Franck Dernoncourt, Yu Wang 0160, Nikos Kanakaris, Hanieh Deilamsalehy, Ryan Rossi, Nesreen K. Ahmed |
PACLIC | 4 |
| 2024 | Memory-Efficient Fine-Tuning of Transformers via Token SelectionabstractFine-tuning provides an effective means to specialize pre-trained models for various downstream tasks.However, fine-tuning often incurs high memory overhead, especially for large transformer-based models, such as LLMs.While existing methods may reduce certain parts of the memory required for fine-tuning, they still require caching all intermediate activations computed in the forward pass to update weights during the backward pass.In this work, we develop TOKENTUNE, a method to reduce memory usage, specifically the memory to store intermediate activations, in the finetuning of transformer-based models.During the backward pass, TOKENTUNE approximates the gradient computation by backpropagating through just a subset of input tokens.Thus, with TOKENTUNE, only a subset of intermediate activations are cached during the forward pass.Also, TOKENTUNE can be easily combined with existing methods like LoRA, further reducing the memory cost.We evaluate our approach on pre-trained transformer models with up to billions of parameters, considering the performance on multiple downstream tasks such as text classification and question answering in a few-shot learning setup.Overall, TOKENTUNE achieves performance on par with full fine-tuning or representative memoryefficient fine-tuning methods, while greatly reducing the memory footprint, especially when combined with other methods with complementary memory reduction mechanisms.We hope that our approach will facilitate the finetuning of large transformers, in specializing them for specific domains or co-training them with other neural components from a larger system.Our code is available at https://github. com/facebookresearch/tokentune. Antoine Simoulin, Namyong Park 0001, Grey Yang |
EMNLP | 2 |
| 2024 | Forward Learning of Graph Neural NetworksabstractGraph neural networks (GNNs) have achieved remarkable success across a wide range of applications, such as recommendation, drug discovery, and question answering. Behind the success of GNNs lies the backpropagation (BP) algorithm, which is the de facto standard for training deep neural networks (NNs). However, despite its effectiveness, BP imposes several constraints, which are not only biologically implausible, but also limit the scalability, parallelism, and flexibility in learning NNs. Examples of such constraints include storage of neural activities computed in the forward pass for use in the subsequent backward pass, and the dependence of parameter updates on non-local signals. To address these limitations, the forward-forward algorithm (FF) was recently proposed as an alternative to BP in the image classification domain, which trains NNs by performing two forward passes over positive and negative data. Inspired by this advance, we propose ForwardGNN in this work, a new forward learning procedure for GNNs, which avoids the constraints imposed by BP via an effective layer-wise local forward training. ForwardGNN extends the original FF to deal with graph data and GNNs, and makes it possible to operate without generating negative inputs (hence no longer forward-forward). Further, ForwardGNN enables each layer to learn from both the bottom-up and top-down signals without relying on the backpropagation of errors. Extensive experiments on real-world datasets show the effectiveness and generality of the proposed forward graph learning framework. We release our code at https://github.com/facebookresearch/forwardgnn. Namyong Park 0001, Antoine Simoulin, Grey Yang, Ryan Rossi, Puja Trivedi, Nesreen K. Ahmed |
ICLR | 1 |
| 2024 | Editing Partially Observable Networks via Graph Diffusion ModelsabstractMost real-world networks are noisy and incomplete samples from an unknown target distribution. Refining them by correcting corruptions or inferring unobserved regions typically improves downstream performance. Inspired by the impressive generative capabilities that have been used to correct corruptions in images, and the similarities between "in-painting" and filling in missing nodes and edges conditioned on the observed graph, we propose a novel graph generative framework, SGDM, which is based on subgraph diffusion. Our framework not only improves the scalability and fidelity of graph diffusion models, but also leverages the reverse process to perform novel, conditional generation tasks. In particular, through extensive empirical analysis and a set of novel metrics, we demonstrate that our proposed model effectively supports the following refinement tasks for partially observable networks: (T1) denoising extraneous subgraphs, (T2) expanding existing subgraphs and (T3) performing ``style" transfer by regenerating a particular subgraph to match the characteristics of a different node or subgraph. Puja Trivedi, Ryan Rossi, David T. Arbour, Tong Yu 0001, Franck Dernoncourt, Sungchul Kim, Nedim Lipka, Namyong Park 0001, Nesreen K. Ahmed, Danai Koutra |
ICML | 8 |
| 2024 | Fairness-Aware Graph Neural Networks: A SurveyabstractGraph Neural Networks (GNNs) have become increasingly important due to their representational power and state-of-the-art predictive performance on many fundamental learning tasks. Despite this success, GNNs suffer from fairness issues that arise as a result of the underlying graph data and the fundamental aggregation mechanism that lies at the heart of the large class of GNN models. In this article, we examine and categorize fairness techniques for improving the fairness of GNNs. We categorize these techniques by whether they focus on improving fairness in the pre-processing, in-processing (during training), or post-processing phases. We discuss how such techniques can be used together whenever appropriate and highlight the advantages and intuition as well. We also introduce an intuitive taxonomy for fairness evaluation metrics, including graph-level fairness, neighborhood-level fairness, embedding-level fairness, and prediction-level fairness metrics. In addition, graph datasets that are useful for benchmarking the fairness of GNN models are summarized succinctly. Finally, we highlight key open problems and challenges that remain to be addressed. April Chen, Ryan Rossi, Namyong Park 0001, Puja Trivedi, Yu Wang 0160, Tong Yu 0001, Sungchul Kim, Franck Dernoncourt, Nesreen K. Ahmed |
ACM Trans. Knowl. Discov. Data | 3 |
| 2023 | TgrApp: Anomaly Detection and Visualization of Large-Scale Call GraphsabstractGiven a million-scale dataset of who-calls-whom data containing imperfect labels, how can we detect existing and new fraud patterns? We propose TgrApp, which extracts carefully designed features and provides visualizations to assist analysts in spotting fraudsters and suspicious behavior. Our TgrApp method has the following properties: (a) Scalable, as it is linear on the input size; and (b) Effective, as it allows natural interaction with human analysts, and is applicable in both supervised and unsupervised settings. Mirela Teixeira Cazzolato, Saranya Vijayakumar, Namyong Park 0001, Meng-Chieh Lee, Polo Chau, Pedro Fidalgo, Bruno Lages, Agma J. M. Traina, Christos Faloutsos |
AAAI | 4 |
| 2023 | CallMine: Fraud Detection and Visualization of Million-Scale Call GraphsabstractGiven a million-scale dataset of who-calls-whom data containing imperfect labels, how can we detect existing and new fraud patterns? We propose CallMine, with carefully designed features and visualizations. Our CallMine method has the following properties: (a) Scalable, being linear on the input size, handling about 35 million records in around one hour on a stock laptop; (b) Effective, allowing natural interaction with human analysts; (c) Flexible, being applicable in both supervised and unsupervised settings; (d) Automatic, requiring no user-defined parameters. Mirela Teixeira Cazzolato, Saranya Vijayakumar, Meng-Chieh Lee, Catalina Vajiac, Namyong Park 0001, Pedro Fidalgo, Agma J. M. Traina, Christos Faloutsos |
CIKM | 5 |
| 2023 | MetaGL: Evaluation-Free Selection of Graph Learning Models via Meta-Learning
Namyong Park 0001, Ryan Rossi, Nesreen K. Ahmed, Christos Faloutsos |
ICLR | 1 |
| 2023 | GLEMOS: Benchmark for Instantaneous Graph Learning Model SelectionabstractThe choice of a graph learning (GL) model (i.e., a GL algorithm and its hyperparameter settings) has a significant impact on the performance of downstream tasks. However, selecting the right GL model becomes increasingly difficult and time consuming as more and more GL models are developed. Accordingly, it is of great significance and practical value to equip users of GL with the ability to perform a near-instantaneous selection of an effective GL model without manual intervention. Despite the recent attempts to tackle this important problem, there has been no comprehensive benchmark environment to evaluate the performance of GL model selection methods. To bridge this gap, we present GLEMOS in this work, a comprehensive benchmark for instantaneous GL model selection that makes the following contributions. (i) GLEMOS provides extensive benchmark data for fundamental GL tasks, i.e., link prediction and node classification, including the performances of 366 models on 457 graphs on these tasks. (ii) GLEMOS designs multiple evaluation settings, and assesses how effectively representative model selection techniques perform in these different settings. (iii) GLEMOS is designed to be easily extended with new models, new graphs, and new performance records. (iv) Based on the experimental results, we discuss the limitations of existing approaches and highlight future research directions. To promote research on this significant problem, we make the benchmark data and code publicly available at https://namyongpark.github.io/glemos. Namyong Park 0001, Ryan Rossi, Antoine Simoulin, Nesreen K. Ahmed, Christos Faloutsos |
NeurIPS | 1 |
| 2023 | DeltaShield: Information Theory for Human- Trafficking DetectionabstractGiven a million escort advertisements, how can we spot near-duplicates? Such micro-clusters of ads are usually signals of human trafficking (HT). How can we summarize them to convince law enforcement to act? Spotting micro-clusters of near-duplicate documents is useful in multiple, additional settings, including spam-bot detection in Twitter ads, plagiarism, and more. We present InfoShield , which makes the following contributions: practical , being scalable and effective on real data; parameter-free and principled , requiring no user-defined parameters; interpretable , finding a document to be the cluster representative, highlighting all the common phrases, and automatically detecting “slots” (i.e., phrases that differ in every document); and generalizable , beating or matching domain-specific methods in Twitter bot detection and HT detection, respectively, as well as being language independent. Interpretability is particularly important for the anti-HT domain, where law enforcement must visually inspect ads. Our experiments on real data show that InfoShield correctly identifies Twitter bots with an F1 score over 90% and detects HT ads with 84% precision. Moreover, it is scalable, requiring about 8 hours for 4 million documents on a stock laptop. Our incremental version, DeltaShield , allows for fast, incremental updates, with minor loss of accuracy. Catalina Vajiac, Meng-Chieh Lee, Aayushi Kulshrestha, Sacha Levy, Namyong Park 0001, Andreas M. Olligschlaeger, Cara Jones, Reihaneh Rabbany, Christos Faloutsos |
ACM Trans. Knowl. Discov. Data | 5 |
| 2023 | TrafficVis: Visualizing Organized Activity and Spatio-Temporal Patterns for Detecting and Labeling Human TraffickingabstractLaw enforcement and domain experts can detect human trafficking (HT) in online escort websites by analyzing suspicious clusters of connected ads. How can we explain clustering results intuitively and interactively, visualizing potential evidence for experts to analyze? We present TRAFFICVIS, the first interface for cluster-level HT detection and labeling. Developed through months of participatory design with domain experts, TRAFFICVIS provides coordinated views in conjunction with carefully chosen backend algorithms to effectively show spatio-temporal and text patterns to a wide variety of anti-HT stakeholders. We build upon state-of-the-art text clustering algorithms by incorporating shared metadata as a signal of connected and possibly suspicious activity, then visualize the results. Domain experts can use TRAFFICVIS to label clusters as HT, or other, suspicious, but non-HT activity such as spam and scam, quickly creating labeled datasets to enable further HT research. Through domain expert feedback and a usage scenario, we demonstrate TRAFFICVIS's efficacy. The feedback was overwhelmingly positive, with repeated high praises for the usability and explainability of our tool, the latter being vital for indicting possible criminals. Catalina Vajiac, Polo Chau, Andreas M. Olligschlaeger, Rebecca Mackenzie, Pratheeksha Nair, Meng-Chieh Lee, Yifei Li 0008, Namyong Park 0001, Reihaneh Rabbany, Christos Faloutsos |
IEEE Trans. Vis. Comput. Graph. | 8 |
| 2022 | TgraphSpot: Fast and Effective Anomaly Detection for Time-Evolving GraphsabstractGiven a large, time-evolving graph of who-calls-whom-when, how can we help analysts find anomalies and fraudsters? How can we explain our decisions? We provide TgraphSpot, which carefully extracts features that are often related to fraud; and which provides informative, interactive plots that help analysts zoom down to the few strange nodes. We present the architecture and design decisions of TgraphSpot. Thanks to our careful feature-extraction algorithms, it scales linearly, taking 2.5 hours on a stock laptop, to process 29 million phone calls. More importantly, when applied on a real dataset of millions of phone calls, it discovered suspicious nodes; experts confirmed that those nodes are fraudsters that had been undetected so far. Mirela Teixeira Cazzolato, Saranya Vijayakumar, Namyong Park 0001, Meng-Chieh Lee, Pedro Fidalgo, Bruno Lages, Agma J. M. Traina, Christos Faloutsos |
IEEE Big Data | 4 |
| 2022 | EvoKG: Jointly Modeling Event Time and Network Structure for Reasoning over Temporal Knowledge GraphsabstractHow can we perform knowledge reasoning over temporal knowledge graphs (TKGs)? TKGs represent facts about entities and their relations, where each fact is associated with a timestamp. Reasoning over TKGs, i.e., inferring new facts from time-evolving KGs, is crucial for many applications to provide intelligent services. However, despite the prevalence of real-world data that can be represented as TKGs, most methods focus on reasoning over static knowledge graphs, or cannot predict future events. In this paper, we present a problem formulation that unifies the two major problems that need to be addressed for an effective reasoning over TKGs, namely, modeling the event time and the evolving network structure. Our proposed method EvoKG jointly models both tasks in an effective framework, which captures the ever-changing structural and temporal dynamics in TKGs via recurrent event modeling, and models the interactions between entities based on the temporal neighborhood aggregation framework. Further, EvoKG achieves an accurate modeling of event time, using flexible and efficient mechanisms based on neural density estimation. Experiments show that EvoKG outperforms existing methods in terms of effectiveness (up to 77% and 116% more accurate time and link prediction) and efficiency. Namyong Park 0001, Fuchen Liu, Purvanshi Mehta, Dana Cristofor, Christos Faloutsos, Yuxiao Dong |
WSDM | 1 |
| 2022 | CGC: Contrastive Graph Clustering forCommunity Detection and TrackingabstractGiven entities and their interactions in the web data, which may have occurred at different time, how can we find communities of entities and track their evolution? In this paper, we approach this important task from graph clustering perspective. Recently, state-of-the-art clustering performance in various domains has been achieved by deep clustering methods. Especially, deep graph clustering (DGC) methods have successfully extended deep clustering to graph-structured data by learning node representations and cluster assignments in a joint optimization framework. Despite some differences in modeling choices (e.g., encoder architectures), existing DGC methods are mainly based on autoencoders and use the same clustering objective with relatively minor adaptations. Also, while many real-world graphs are dynamic, previous DGC methods considered only static graphs. In this work, we develop CGC, a novel end-to-end framework for graph clustering, which fundamentally differs from existing methods. CGC learns node embeddings and cluster assignments in a contrastive graph learning framework, where positive and negative samples are carefully selected in a multi-level scheme such that they reflect hierarchical community structures and network homophily. Also, we extend CGC for time-evolving data, where temporal graph clustering is performed in an incremental learning fashion, with the ability to detect change points. Extensive evaluation on real-world graphs demonstrates that the proposed CGC consistently outperforms existing methods. Namyong Park 0001, Ryan Rossi, Eunyee Koh, Iftikhar Ahamath Burhanuddin, Sungchul Kim, Fan Du, Nesreen K. Ahmed, Christos Faloutsos |
WWW | 1 |
| 2021 | INFOSHIELD: Generalizable Information-Theoretic Human-Trafficking DetectionabstractGiven a million escort advertisements, how can we spot near-duplicates? Such micro-clusters of ads are usually signals of human trafficking. How can we summarize them, visually, to convince law enforcement to act? Can we build a general tool that works for different languages? Spotting micro-clusters of near-duplicate documents is useful in multiple, additional settings, including spam-bot detection in Twitter ads, plagiarism, and more.We present INFOSHIELD, which makes the following contributions: (a) Practical, being scalable and effective on real data, (b) Parameter-free and Principled, requiring no user-defined parameters, (c) Interpretable, finding a document to be the cluster representative, highlighting all the common phrases, and automatically detecting "slots", i.e. phrases that differ in every document; and (d) Generalizable, beating or matching domain-specific methods in Twitter bot detection and human trafficking detection respectively, as well as being language-independent finding clusters in Spanish, Italian, and Japanese. Interpretability is particularly important for the anti human-trafficking domain, where law enforcement must visually inspect ads.Our experiments on real data show that INFOSHIELD correctly identifies Twitter bots with an F1 score over 90% and detects human-trafficking ads with 84% precision. Moreover, it is scalable, requiring about 8 hours for 4 million documents on a stock laptop. Meng-Chieh Lee, Catalina Vajiac, Aayushi Kulshrestha, Sacha Levy, Namyong Park 0001, Cara Jones, Reihaneh Rabbany, Christos Faloutsos |
ICDE | 5 |
| 2021 | Knowledge-Based Dynamic Systems Modeling: A Case Study on Modeling River Water QualityabstractModeling real-world phenomena is a focus of many science and engineering efforts, from ecological modeling to financial forecasting. Building an accurate model for complex and dynamic systems improves understanding of underlying processes and leads to resource efficiency. Knowledge-driven modeling builds a model based on human expertise, yet is often suboptimal. At the opposite extreme, data-driven modeling learns a model directly from data, requiring extensive data and potentially generating overfitting. We focus on an intermediate approach, model revision, in which prior knowledge and data are combined to achieve the best of both worlds. We propose a genetic model revision framework based on tree-adjoining grammar (TAG) guided genetic programming (GP), using the TAG formalism and GP operators in an effective mechanism making data-driven revisions while incorporating prior knowledge. Our framework is designed to address the high computational cost of evolutionary modeling of complex systems. Via a case study on the challenging problem of river water quality modeling, we show that the framework efficiently learns an interpretable model, with higher modeling accuracy than existing methods. Namyong Park 0001, Minhyeok Kim 0001, Nguyen Xuan Hoai, Robert I. McKay, Dong-Kyun Kim |
ICDE | 1 |
| 2020 | J-Recs: Principled and Scalable Recommendation JustificationabstractOnline recommendation is an essential functionality across a variety of services, including e-commerce and video streaming, where items to buy, watch, or read are suggested to users. Justifying recommendations, i.e., explaining why a user might like the recommended item, has been shown to improve user satisfaction and persuasiveness of the recommendation. In this paper, we develop a method for generating post-hoc justifications that can be applied to the output of any recommendation algorithm. Existing post-hoc methods are often limited in providing diverse justifications, as they either use only one of many available types of input data, or rely on the predefined templates. We address these limitations of earlier approaches by developing J-Recs, a method for producing concise and diverse justifications. J-Recs is a recommendation model-agnostic method that generates diverse justifications based on various types of product and user data (e.g., purchase history and product attributes). The challenge of jointly processing multiple types of data is addressed by designing a principled graph-based approach for justification generation. In addition to theoretical analysis, we present an extensive evaluation on synthetic and real-world data. Our results show that J-Recs satisfies desirable properties of justifications, and efficiently produces effective justifications, matching user preferences up to 20% more accurately than baselines. Namyong Park 0001, Andrey Kan, Christos Faloutsos, Xin Dong 0001 |
ICDM | 1 |
| 2020 | MultiImport: Inferring Node Importance in a Knowledge Graph from Multiple Input SignalsabstractGiven multiple input signals, how can we infer node importance in a knowledge graph (KG)? Node importance estimation is a crucial and challenging task that can benefit a lot of applications including recommendation, search, and query disambiguation. A key challenge towards this goal is how to effectively use input from different sources. On the one hand, a KG is a rich source of information, with multiple types of nodes and edges. On the other hand, there are external input signals, such as the number of votes or pageviews, which can directly tell us about the importance of entities in a KG. While several methods have been developed to tackle this problem, their use of these external signals has been limited as they are not designed to consider multiple signals simultaneously. In this paper, we develop an end-to-end model MultiImport, which infers latent node importance from multiple, potentially overlapping, input signals. MultiImport is a latent variable model that captures the relation between node importance and input signals, and effectively learns from multiple signals with potential conflicts. Also, MultiImport provides an effective estimator based on attentive graph neural networks. We ran experiments on real-world KGs to show that MultiImport handles several challenges involved with inferring node importance from multiple input signals, and consistently outperforms existing methods, achieving up to 23.7% higher [email protected] than the state-of-the-art method. Namyong Park 0001, Andrey Kan, Xin Dong 0001, Tong Zhao 0002, Christos Faloutsos |
KDD | 1 |
| 2019 | Estimating Node Importance in Knowledge Graphs Using Graph Neural NetworksabstractHow can we estimate the importance of nodes in a knowledge graph (KG)? A KG is a multi-relational graph that has proven valuable for many tasks including question answering and semantic search. In this paper, we present GENI, a method for tackling the problem of estimating node importance in KGs, which enables several downstream applications such as item recommendation and resource allocation. While a number of approaches have been developed to address this problem for general graphs, they do not fully utilize information available in KGs, or lack flexibility needed to model complex relationship between entities and their importance. To address these limitations, we explore supervised machine learning algorithms. In particular, building upon recent advancement of graph neural networks (GNNs), we develop GENI, a GNN-based method designed to deal with distinctive challenges involved with predicting node importance in KGs. Our method performs an aggregation of importance scores instead of aggregating node embeddings via predicate-aware attention mechanism and flexible centrality adjustment. In our evaluation of GENI and existing methods on predicting node importance in real-world KGs with different characteristics, GENI achieves 5-17% higher [email protected] than the state of the art. Namyong Park 0001, Andrey Kan, Xin Dong 0001, Tong Zhao 0002, Christos Faloutsos |
KDD | 1 |
| 2019 | High-Performance Tucker Factorization on Heterogeneous PlatformsabstractGiven large-scale multi-dimensional data (e.g., (user, movie, time; rating) for movie recommendations), how can we extract latent concepts/relations of such data? Tensor factorization has been widely used to solve such problems with multi-dimensional data, which are modeled as tensors. However, most tensor factorization algorithms exhibit limited scalability and speed since they require huge memory and heavy computational costs while updating factor matrices. In this paper, we propose GTA, a general framework for Tucker factorization on heterogeneous platforms. GTA performs alternating least squares with a row-wise update rule in a fully parallel way, which significantly reduces memory requirements for updating factor matrices. Furthermore, GTA provides two algorithms: GTA-PART for partially observable tensors and GTA-FULL for fully observable tensors, both of which accelerate the update process using GPUs and CPUs. Experimental results show that GTA exhibits 5.6~44.6× speed-up for large-scale tensors compared to the state-of-the-art. In addition, GTA scales near linearly with the number of GPUs and computing nodes used for experiments. Sejoon Oh, Namyong Park 0001, Jun-Gi Jang, Lee Sael, U Kang |
IEEE Trans. Parallel Distributed Syst. | 2 |
| 2019 | Fast and scalable method for distributed Boolean tensor factorization
Namyong Park 0001, Sejoon Oh, U Kang |
VLDB J. | 1 |
| 2018 | Scalable Tucker Factorization for Sparse Tensors - Algorithms and DiscoveriesabstractGiven sparse multi-dimensional data (e.g., (user, movie, time; rating) for movie recommendations), how can we discover latent concepts/relations and predict missing values? Tucker factorization has been widely used to solve such problems with multi-dimensional data, which are modeled as tensors. However, most Tucker factorization algorithms regard and estimate missing entries as zeros, which triggers a highly inaccurate decomposition. Moreover, few methods focusing on an accuracy exhibit limited scalability since they require huge memory and heavy computational costs while updating factor matrices. In this paper, we propose P-Tucker, a scalable Tucker factorization method for sparse tensors. P-Tucker performs alternating least squares with a row-wise update rule in a fully parallel way, which significantly reduces memory requirements for updating factor matrices. Furthermore, we offer two variants of P-Tucker: a caching algorithm P-Tucker-Cache and an approximation algorithm P-Tucker-Approx, both of which accelerate the update process. Experimental results show that P-Tucker exhibits 1.7-14.1x speed-up and 1.4-4.8x less error compared to the state-of-the-art. In addition, P-Tucker scales near linearly with the number of observable entries in a tensor and number of threads. Thanks to P-Tucker, we successfully discover hidden concepts and relations in a large-scale real-world tensor, while existing methods cannot reveal latent features due to their limited scalability or low accuracy. Sejoon Oh, Namyong Park 0001, Lee Sael, U Kang |
ICDE | 2 |
| 2017 | Fast and Scalable Distributed Boolean Tensor FactorizationabstractHow can we analyze tensors that are composed of 0's and 1's? How can we efficiently analyze such Boolean tensors with millions or even billions of entries? Boolean tensors often represent relationship, membership, or occurrences of events such as subject-relation-object tuples in knowledge base data (e.g., 'Seoul'-'is the capital of'-'South Korea'). Boolean tensor factorization (BTF) is a useful tool for analyzing binary tensors to discover latent factors from them. Furthermore, BTF is known to produce more interpretable and sparser results than normal factorization methods. Although several BTF algorithms exist, they do not scale up for large-scale Boolean tensors. In this paper, we propose DBTF, a distributed algorithm for Boolean tensor factorization running on the Spark framework. By caching computation results, exploiting the characteristics of Boolean operations, and with careful partitioning, DBTF successfully tackles the high computational costs and minimizes the intermediate data. Experimental results show that DBTF decomposes up to 163-323 larger tensors than existing methods in 68-382 less time, and exhibits near-linear scalability in terms of tensor dimensionality, density, rank, and machines. Namyong Park 0001, Sejoon Oh, U Kang |
ICDE | 1 |
| 2017 | BePI: Fast and Memory-Efficient Method for Billion-Scale Random Walk with RestartabstractHow can we measure similarity between nodes quickly and accurately on large graphs? Random walk with restart (RWR) provides a good measure, and has been used in various data mining applications including ranking, recommendation, link prediction and community detection. However, existing methods for computing RWR do not scale to large graphs containing billions of edges; iterative methods are slow in query time, and preprocessing methods require too much memory. Jinhong Jung, Namyong Park 0001, Lee Sael, U Kang |
SIGMOD Conference | 2 |
| 2016 | BIGtensor: Mining Billion-Scale Tensor Made EasyabstractMany real-world data are naturally represented as tensors, or multi-dimensional arrays. Tensor decomposition is an important tool to analyze tensors for various applications such as latent concept discovery, trend analysis, clustering, and anomaly detection. However, existing tools for tensor analysis do not scale well for billion-scale tensors or offer limited functionalities. In this paper, we propose BIGtensor, a large-scale tensor mining library that tackles both of the above problems. Carefully designed for scalability, BIGtensor decomposes at least 100× larger tensors than the current state of the art. Furthermore, BIGtensor provides a variety of distributed tensor operations and tensor generation methods. We demonstrate how BIGtensor can help users discover hidden concepts and analyze trends from large-scale tensors that are hard to be processed by existing tensor tools. Namyong Park 0001, Byungsoo Jeon, U Kang |
CIKM | 1 |
| 2016 | Partition Aware Connected Component Computation in Distributed SystemsabstractHow can we find all connected components in an enormous graph with billions of nodes and edges?Finding connected components is a fundamental operation for various graph computation tasks such as pattern recognition, reachability, graph compression, etc. Many algorithms have been proposed for decades, but most of them are not scalable enough to process recent web scale graphs. Recently, a MapReduce algorithm was proposed to handle such large graphs. However, the algorithm repeatedly reads and writes numerous intermediate data that cause network overload and prolong the running time. In this paper, we propose PACC (Partition-Aware Connected Components), a new distributed algorithm based on graph partitioning for load-balancing and edge-filtering. Experimental results show that PACC significantly reduces the intermediate data, and provides up to 10 times faster performance than the current state-of-the-art MapReduce algorithm on real world graphs. Ha-Myung Park, Namyong Park 0001, Sung-Hyon Myaeng, U Kang |
ICDM | 2 |
| 2013 | Cutting evaluation costs: An investigation into early termination in genetic programmingabstractGenetic programming is very computationally intensive, particularly in CPU time. A number of approaches to evaluation cost reduction have been proposed, among them early termination of evaluation (applicable in problem domains where estimates of the final fitness value are available during evaluation). Like all cost reduction techniques, early termination balances overall computation cost against the risk of finding worse solutions. We evaluate the influence of various properties of the problem domain - problem class, reliability of fitness estimates, trajectory of fitness estimates, and evolutionary trajectory - to determine whether any is able to predict the effects of early termination. There is little correlation with any of these, with one exception. Boolean problems see little change in running time, and hence only small changes in performance, are distinguished by both problem class, and each of the other metrics. Namyong Park 0001, Kangil Kim, Robert I. McKay |
IEEE Congress on Evolutionary Computation | 1 |
| 2012 | Evolving the best known approximation to the Q functionabstractThe Gaussian Q-function is the integral of the tail of the Gaussian distribution; as such, it is important across a vast range of fields requiring stochastic analysis. No elementary closed form is possible, so a number of approximations have been proposed. We use a Genetic Programming (GP) system, Tree Adjoining Grammar Guided GP (TAG3P) with local search operators to evolve approximations of the Q-function in the form given by Benitez [1]. We found more accurate approximations than any previously published. This confirms the practical importance of local search in TAG3P. Dao Ngoc Phong, Nguyen Xuan Hoai, Robert I. McKay, Constantin Siriteanu, Nguyen Quang Uy, Namyong Park 0001 |
GECCO | 6 |