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Dixin Luo

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15 papers

2 author rows

AAAI Conference 2025 Conference Paper

WatE: A Wasserstein t-distributed Embedding Method for Information-enriched Graph Visualization

Minjie Cheng
Dixin Luo
Hongteng Xu

As a fundamental problem of graph analysis, graph visualization aims to embed a set of graphs in a low-dimensional (e.g., 2D) space and provide insights into their distribution and clustering structure. Focusing on this problem, we propose a novel Wasserstein t-distributed embedding (WatE) method, leading to an information-enriched graph visualization paradigm. Our method learns a graph neural network to represent each graph as the mean and covariance of its node embedding distribution. Accordingly, our method can visualize each graph as an ellipse (determined by the mean and the covariance) rather than a single point. The positions of different ellipses reveal the relations among different graphs as traditional visualization methods do, while the size and shape of an ellipse preserve the node-level structural information of the corresponding graph. We propose a regularized t-distributed stochastic neighbor embedding (Rt-SNE) framework to learn the visualization model, deriving a Wasserstein distance-based Student's t-distribution of graph pairs and fitting the distribution to the data distribution under regularization. Both subjective and objective evaluations demonstrate that WatE achieves encouraging performance in various graph visualization and clustering tasks.

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IJCAI Conference 2025 Conference Paper

Weakly-Supervised Movie Trailer Generation Driven by Multi-Modal Semantic Consistency

Sidan Zhu
Yutong Wang
Hongteng Xu
Dixin Luo

As an essential movie promotional tool, trailers are designed to capture the audience's interest through the skillful editing of key movie shots. Although some attempts have been made for automatic trailer generation, existing methods often rely on predefined rules or manual fine-grained annotations and fail to fully leverage the multi-modal information of movies, resulting in unsatisfactory trailer generation results. In this study, we introduce a weakly-supervised trailer generation method driven by multi-modal semantic consistency. Specifically, we design a multi-modal trailer generation framework that selects and sorts key movie shots based on input music and movie metadata (e. g. , category tags and plot keywords) and adds narration to the generated trailer based on movie subtitles. We utilize two pseudo-scores derived from the proposed framework as labels and thus train the model under a weakly-supervised learning paradigm, ensuring trailerness consistency for key shot selection and emotion consistency for key shot sorting, respectively. As a result, we can learn the proposed model solely based on movie-trailer pairs without any fine-grained annotations. Both objective experimental results and subjective user studies demonstrate the superior performance of our method over previous works. The code is available at https: //github. com/Dixin-Lab/MMSC.

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AAAI Conference 2024 Conference Paper

A Plug-and-Play Quaternion Message-Passing Module for Molecular Conformation Representation

Angxiao Yue
Dixin Luo
Hongteng Xu

Graph neural networks have been widely used to represent 3D molecules, which capture molecular attributes and geometric information through various message-passing mechanisms. This study proposes a novel quaternion message-passing (QMP) module that can be plugged into many existing 3D molecular representation models and enhance their power for distinguishing molecular conformations. In particular, our QMP module represents the 3D rotations between one chemical bond and its neighbor bonds as a quaternion sequence. Then, it aggregates the rotations by the chained Hamilton product of the quaternions. The real part of the output quaternion is invariant to the global 3D rotations of molecules but sensitive to the local torsions caused by twisting bonds, providing discriminative information for training molecular conformation representation models. In theory, we prove that considering these features enables invariant GNNs to distinguish the conformations caused by bond torsions. We encapsulate the QMP module with acceleration, so combining existing models with the QMP requires merely one-line code and little computational cost. Experiments on various molecular datasets show that plugging our QMP module into existing invariant GNNs leads to consistent and significant improvements in molecular conformation representation and downstream tasks.

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IJCAI Conference 2024 Conference Paper

Inferring Iterated Function Systems Approximately from Fractal Images

Haotian Liu
Dixin Luo
Hongteng Xu

As an important mathematical concept, fractals commonly appear in nature and inspire the design of many artistic works. Although we can generate various fractal images easily based on different iterated function systems (IFSs), inferring an IFS from a given fractal image is still a challenging inverse problem for both scientific research and artistic design. In this study, we explore the potential of deep learning techniques for this problem, learning a multi-head auto-encoding model to infer typical IFSs (including Julia set and L-system) from fractal images. In principle, the proposed model encodes fractal images in a latent space and decodes their corresponding IFSs based on the latent representations. For the fractal images generated by heterogeneous IFSs, we let them share the same encoder and apply two decoders to infer the sequential and non-sequential parameters of their IFSs, respectively. By introducing one more decoder to reconstruct fractal images, we can leverage large-scale unlabeled fractal images to learn the model in a semi-supervised way, which suppresses the risk of over-fitting. Comprehensive experiments demonstrate that our method provides a promising solution to infer IFSs approximately from fractal images. Code and supplementary file are available at \url{https: //github. com/HaotianLiu123/Inferring-IFSs-From-Fractal-Images}.

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IJCAI Conference 2023 Conference Paper

Coupled Point Process-based Sequence Modeling for Privacy-preserving Network Alignment

Dixin Luo
Haoran Cheng
Qingbin Li
Hongteng Xu

Network alignment aims at finding the correspondence of nodes across different networks, which is significant for many applications, e. g. , fraud detection and crime network tracing across platforms. In practice, however, accessing the topological information of different networks is often restricted and even forbidden, considering privacy and security issues. Instead, what we observed might be the event sequences of the networks' nodes in the continuous-time domain. In this study, we develop a coupled neural point process-based (CPP) sequence modeling strategy, which provides a solution to privacy-preserving network alignment based on the event sequences. Our CPP consists of a coupled node embedding layer and a neural point process module. The coupled node embedding layer embeds one network's nodes and explicitly models the alignment matrix between the two networks. Accordingly, it parameterizes the node embeddings of the other network by the push-forward operation. Given the node embeddings, the neural point process module jointly captures the dynamics of the two networks' event sequences. We learn the CPP model in a maximum likelihood estimation framework with an inverse optimal transport (IOT) regularizer. Experiments show that our CPP is compatible with various point process backbones and is robust to the model misspecification issue, which achieves encouraging performance on network alignment. The code is available at https: //github. com/Dixin-s-Lab/CNPP.

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IJCAI Conference 2023 Conference Paper

Group Sparse Optimal Transport for Sparse Process Flexibility Design

Dixin Luo
Tingting Yu
Hongteng Xu

As a fundamental problem in Operations Research, sparse process flexibility design (SPFD) aims to design a manufacturing network across industries that achieves a trade-off between the efficiency and robustness of supply chains. In this study, we propose a novel solution to this problem with the help of computational optimal transport techniques. Given a set of supply-demand pairs, we formulate the SPFD task approximately as a group sparse optimal transport (GSOT) problem, in which a group of couplings between the supplies and demands is optimized with a group sparse regularizer. We solve this optimization problem via an algorithmic framework of alternating direction method of multipliers (ADMM), in which the target network topology is updated by soft-thresholding shrinkage, and the couplings of the OT problems are updated via a smooth OT algorithm in parallel. This optimization algorithm has guaranteed convergence and provides a generalized framework for the SPFD task, which is applicable regardless of whether the supplies and demands are balanced. Experiments show that our GSOT-based method can outperform representative heuristic methods in various SPFD tasks. Additionally, when implementing the GSOT method, the proposed ADMM-based optimization algorithm is comparable or superior to the commercial software Gurobi. The code is available at https: //github. com/Dixin-s-Lab/GSOT.

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AAAI Conference 2023 Conference Paper

Privacy-Preserved Evolutionary Graph Modeling via Gromov-Wasserstein Autoregression

Yue Xiang
Dixin Luo
Hongteng Xu

Real-world graphs like social networks are often evolutionary over time, whose observations at different timestamps lead to graph sequences. Modeling such evolutionary graphs is important for many applications, but solving this problem often requires the correspondence between the graphs at different timestamps, which may leak private node information, e.g., the temporal behavior patterns of the nodes. We proposed a Gromov-Wasserstein Autoregressive (GWAR) model to capture the generative mechanisms of evolutionary graphs, which does not require the correspondence information and thus preserves the privacy of the graphs' nodes. This model consists of two autoregressions, predicting the number of nodes and the probabilities of nodes and edges, respectively. The model takes observed graphs as its input and predicts future graphs via solving a joint graph alignment and merging task. This task leads to a fused Gromov-Wasserstein (FGW) barycenter problem, in which we approximate the alignment of the graphs based on a novel inductive fused Gromov-Wasserstein (IFGW) distance. The IFGW distance is parameterized by neural networks and can be learned under mild assumptions, thus, we can infer the FGW barycenters without iterative optimization and predict future graphs efficiently. Experiments show that our GWAR achieves encouraging performance in modeling evolutionary graphs in privacy-preserving scenarios.

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AAAI Conference 2021 Conference Paper

Learning Graphons via Structured Gromov-Wasserstein Barycenters

Hongteng Xu
Dixin Luo
Lawrence Carin
Hongyuan Zha

We propose a novel and principled method to learn a nonparametric graph model called graphon, which is defined in an infinite-dimensional space and represents arbitrary-size graphs. Based on the weak regularity lemma from the theory of graphons, we leverage a step function to approximate a graphon. We show that the cut distance of graphons can be relaxed to the Gromov-Wasserstein distance of their step functions. Accordingly, given a set of graphs generated by an underlying graphon, we learn the corresponding step function as the Gromov-Wasserstein barycenter of the given graphs. Furthermore, we develop several enhancements and extensions of the basic algorithm, e. g. , the smoothed Gromov- Wasserstein barycenter for guaranteeing the continuity of the learned graphons and the mixed Gromov-Wasserstein barycenters for learning multiple structured graphons. The proposed approach overcomes drawbacks of prior state-ofthe-art methods, and outperforms them on both synthetic and real-world data. The code is available at https: //github. com/ HongtengXu/SGWB-Graphon.

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ICML Conference 2020 Conference Paper

Learning Autoencoders with Relational Regularization

Hongteng Xu
Dixin Luo
Ricardo Henao
Svati Shah
Lawrence Carin

We propose a new algorithmic framework for learning autoencoders of data distributions. In this framework, we minimize the discrepancy between the model distribution and the target one, with relational regularization on learnable latent prior. This regularization penalizes the fused Gromov-Wasserstein (FGW) distance between the latent prior and its corresponding posterior, which allows us to learn a structured prior distribution associated with the generative model in a flexible way. Moreover, it helps us co-train multiple autoencoders even if they are with heterogeneous architectures and incomparable latent spaces. We implement the framework with two scalable algorithms, making it applicable for both probabilistic and deterministic autoencoders. Our relational regularized autoencoder (RAE) outperforms existing methods, e. g. , variational autoencoder, Wasserstein autoencoder, and their variants, on generating images. Additionally, our relational co-training strategy of autoencoders achieves encouraging results in both synthesis and real-world multi-view learning tasks.

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ICML Conference 2019 Conference Paper

Gromov-Wasserstein Learning for Graph Matching and Node Embedding

Hongteng Xu
Dixin Luo
Hongyuan Zha
Lawrence Carin

A novel Gromov-Wasserstein learning framework is proposed to jointly match (align) graphs and learn embedding vectors for the associated graph nodes. Using Gromov-Wasserstein discrepancy, we measure the dissimilarity between two graphs and find their correspondence, according to the learned optimal transport. The node embeddings associated with the two graphs are learned under the guidance of the optimal transport, the distance of which not only reflects the topological structure of each graph but also yields the correspondence across the graphs. These two learning steps are mutually-beneficial, and are unified here by minimizing the Gromov-Wasserstein discrepancy with structural regularizers. This framework leads to an optimization problem that is solved by a proximal point method. We apply the proposed method to matching problems in real-world networks, and demonstrate its superior performance compared to alternative approaches.

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NeurIPS Conference 2019 Conference Paper

Scalable Gromov-Wasserstein Learning for Graph Partitioning and Matching

Hongteng Xu
Dixin Luo
Lawrence Carin

We propose a scalable Gromov-Wasserstein learning (S-GWL) method and establish a novel and theoretically-supported paradigm for large-scale graph analysis. The proposed method is based on the fact that Gromov-Wasserstein discrepancy is a pseudometric on graphs. Given two graphs, the optimal transport associated with their Gromov-Wasserstein discrepancy provides the correspondence between their nodes and achieves graph matching. When one of the graphs is a predefined graph with isolated but self-connected nodes ($i. e. $, disconnected graph), the optimal transport indicates the clustering structure of the other graph and achieves graph partitioning. Further, we extend our method to multi-graph partitioning and matching by learning a Gromov-Wasserstein barycenter graph for multiple observed graphs. Our method combines a recursive $K$-partition mechanism with a warm-start proximal gradient algorithm, whose time complexity is $\mathcal{O}(K(E+V)\log_K V)$ for graphs with $V$ nodes and $E$ edges. To our knowledge, our method is the first attempt to make Gromov-Wasserstein discrepancy applicable to large-scale graph analysis and unify graph partitioning and matching into the same framework. It outperforms state-of-the-art graph partitioning and matching methods, achieving a trade-off between accuracy and efficiency.

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IJCAI Conference 2018 Conference Paper

Online Continuous-Time Tensor Factorization Based on Pairwise Interactive Point Processes

Hongteng Xu
Dixin Luo
Lawrence Carin

A continuous-time tensor factorization method is developed for event sequences containing multiple "modalities. " Each data element is a point in a tensor, whose dimensions are associated with the discrete alphabet of the modalities. Each tensor data element has an associated time of occurence and a feature vector. We model such data based on pairwise interactive point processes, and the proposed framework connects pairwise tensor factorization with a feature-embedded point process. The model accounts for interactions within each modality, interactions across different modalities, and continuous-time dynamics of the interactions. Model learning is formulated as a convex optimization problem, based on online alternating direction method of multipliers. Compared to existing state-of-the-art methods, our approach captures the latent structure of the tensor and its evolution over time, obtaining superior results on real-world datasets.

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ICML Conference 2017 Conference Paper

Learning Hawkes Processes from Short Doubly-Censored Event Sequences

Hongteng Xu
Dixin Luo
Hongyuan Zha

Many real-world applications require robust algorithms to learn point process models based on a type of incomplete data — the so-called short doubly-censored (SDC) event sequences. In this paper, we study this critical problem of quantitative asynchronous event sequence analysis under the framework of Hawkes processes by leveraging the general idea of data synthesis. In particular, given SDC event sequences observed in a variety of time intervals, we propose a sampling-stitching data synthesis method — sampling predecessor and successor for each SDC event sequence from potential candidates and stitching them together to synthesize long training sequences. The rationality and the feasibility of our method are discussed in terms of arguments based on likelihood. Experiments on both synthetic and real-world data demonstrate that the proposed data synthesis method improves learning results indeed for both time-invariant and time-varying Hawkes processes.

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AAAI Conference 2015 Conference Paper

Dictionary Learning with Mutually Reinforcing Group-Graph Structures

Hongteng Xu
Licheng Yu
Dixin Luo
Hongyuan Zha
Yi Xu

In this paper, we propose a novel dictionary learning method in the semi-supervised setting by dynamically coupling graph and group structures. To this end, samples are represented by sparse codes inheriting their graph structure while the labeled samples within the same class are represented with group sparsity, sharing the same atoms of the dictionary. Instead of statically combining graph and group structures, we take advantage of them in a mutually reinforcing way — in the dictionary learning phase, we introduce the unlabeled samples into groups by an entropy-based method and then update the corresponding local graph, resulting in a more structured and discriminative dictionary. We analyze the relationship between the two structures and prove the convergence of our proposed method. Focusing on image classification task, we evaluate our approach on several datasets and obtain superior performance compared with the state-of-the-art methods, especially in the case of only a few labeled samples and limited dictionary size.

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IJCAI Conference 2015 Conference Paper

Multi-Task Multi-Dimensional Hawkes Processes for Modeling Event Sequences

Dixin Luo
Hongteng Xu
Yi Zhen
Xia Ning
Hongyuan Zha
Xiaokang Yang
Wenjun Zhang

We propose a Multi-task Multi-dimensional Hawkes Process (MMHP) for modeling event sequences where there exist multiple triggering patterns within sequences and structures across sequences. MMHP is able to model the dynamics of multiple sequences jointly by imposing structural constraints and thus systematically uncover clustering structure among sequences. We propose an effective and robust optimization algorithm to learn MMHP models, which takes advantage of alternating direction method of multipliers (ADMM), majorization minimization and Euler-Lagrange equations. Our experimental results demonstrate that MMHP performs well on both synthetic and real data.

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