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Wendi Ren

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4 papers

2 author rows

UAI Conference 2025 Conference Paper

Flow-Based Delayed Hawkes Process

Chao Yang
Wendi Ren
Shuang Li 0002

Multivariate Hawkes processes are classic temporal point process models for event data. These models are simple and parametric in nature, offering interpretability by capturing the triggering effects between event types. However, these parametric models often struggle with low model capacity, limiting their expressive power to capture heterogeneous data patterns influenced by latent variables. In this paper, we propose a simple yet powerful extension: the Flow-based Delayed Hawkes Process, which integrates Normalizing Flows as a generative model to parameterize the Hawkes process. By generating all model parameters through the flow-based network, our approach significantly improves flexibility and expressiveness while preserving interpretability. We provide theoretical guarantees by proving the identifiability of the model parameters and the consistency of the maximum likelihood estimator under mild assumptions. Extensive experiments on both synthetic and real-world datasets show that our model outperforms existing baselines in capturing intricate and heterogeneous event dynamics.

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ICLR Conference 2025 Conference Paper

Logic-Logit: A Logic-Based Approach to Choice Modeling

Shuhan Zhang
Wendi Ren
Shuang Li 0002

In this study, we propose a novel rule-based interpretable choice model, {\bf Logic-Logit}, designed to effectively learn and explain human choices. Choice models have been widely applied across various domains—such as commercial demand forecasting, recommendation systems, and consumer behavior analysis—typically categorized as parametric, nonparametric, or deep network-based. While recent innovations have favored neural network approaches for their computational power, these flexible models often involve large parameter sets and lack interpretability, limiting their effectiveness in contexts where transparency is essential. Previous empirical evidence shows that individuals usually use {\it heuristic decision rules} to form their consideration sets, from which they then choose. These rules are often represented as {\it disjunctions of conjunctions} (i.e., OR-of-ANDs). These rules-driven, {\it consider-then-choose} decision processes enable people to quickly screen numerous alternatives while reducing cognitive and search costs. Motivated by this insight, our approach leverages logic rules to elucidate human choices, providing a fresh perspective on preference modeling. We introduce a unique combination of column generation techniques and the Frank-Wolfe algorithm to facilitate efficient rule extraction for preference modeling—a process recognized as NP-hard. Our empirical evaluation, conducted on both synthetic datasets and real-world data from commercial and healthcare domains, demonstrates that Logic-Logit significantly outperforms baseline models in terms of interpretability and accuracy.

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ICLR Conference 2024 Conference Paper

Amortized Network Intervention to Steer the Excitatory Point Processes

Zitao Song
Wendi Ren
Shuang Li 0002

Excitatory point processes (i.e., event flows) occurring over dynamic graphs (i.e., evolving topologies) provide a fine-grained model to capture how discrete events may spread over time and space. How to effectively steer the event flows by modifying the dynamic graph structures presents an interesting problem, motivated by curbing the spread of infectious diseases through strategically locking down cities to mitigating traffic congestion via traffic light optimization. To address the intricacies of planning and overcome the high dimensionality inherent to such decision-making problems, we design an Amortized Network Interventions (ANI) framework, allowing for the pooling of optimal policies from history and other contexts while ensuring a permutation equivalent property. This property enables efficient knowledge transfer and sharing across diverse contexts. Each task is solved by an H-step lookahead model-based reinforcement learning, where neural ODEs are introduced to model the dynamics of the excitatory point processes. Instead of simulating rollouts from the dynamics model, we derive an analytical mean-field approximation for the event flows given the dynamics, making the online planning more efficiently solvable. We empirically illustrate that this ANI approach substantially enhances policy learning for unseen dynamics and exhibits promising outcomes in steering event flows through network intervention using synthetic and real COVID datasets.

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NeurIPS Conference 2024 Conference Paper

HyperLogic: Enhancing Diversity and Accuracy in Rule Learning with HyperNets

Yang Yang
Wendi Ren
Shuang Li

Exploring the integration of if-then logic rules within neural network architectures presents an intriguing area. This integration seamlessly transforms the rule learning task into neural network training using backpropagation and stochastic gradient descent. From a well-trained sparse and shallow neural network, one can interpret each layer and neuron through the language of logic rules, and a global explanatory rule set can be directly extracted. However, ensuring interpretability may impose constraints on the flexibility, depth, and width of neural networks. In this paper, we propose HyperLogic: a novel framework leveraging hypernetworks to generate weights of the main network. HyperLogic can unveil multiple diverse rule sets, each capable of capturing heterogeneous patterns in data. This provides a simple yet effective method to increase model flexibility and preserve interpretability. We theoretically analyzed the benefits of the HyperLogic by examining the approximation error and generalization capabilities under two types of regularization terms: sparsity and diversity regularizations. Experiments on real data demonstrate that our method can learn more diverse, accurate, and concise rules.

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