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Mong Li Lee

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13 papers

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IJCAI Conference 2025 Conference Paper

ChronoFact: Timeline-based Temporal Fact Verification

Anab Maulana Barik
Wynne Hsu
Mong Li Lee

Temporal claims, often riddled with inaccuracies, are a significant challenge in the digital misinformation landscape. Fact-checking systems that can accurately verify such claims are crucial for combating misinformation. Current systems struggle with the complexities of evaluating the accuracy of these claims, especially when they include multiple, overlapping, or recurring events. We introduce a novel timeline-based fact verification framework that identify events from both claim and evidence and organize them into their respective chronological timelines. The framework systematically examines the relationships between the events in both claim and evidence to predict the veracity of each claim event and their chronological accuracy. This allows us to accurately determine the overall veracity of the claim. We also introduce a new dataset of complex temporal claims involving timeline-based reasoning for the training and evaluation of our proposed framework. Experimental results demonstrate the effectiveness of our approach in handling the intricacies of temporal claim verification.

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IJCAI Conference 2024 Conference Paper

Cross-Domain Feature Augmentation for Domain Generalization

Yingnan Liu
Yingtian Zou
Rui Qiao
Fusheng Liu
Mong Li Lee
Wynne Hsu

Domain generalization aims to develop models that are robust to distribution shifts. Existing methods focus on learning invariance across domains to enhance model robustness, and data augmentation has been widely used to learn invariant predictors, with most methods performing augmentation in the input space. However, augmentation in the input space has limited diversity whereas in the feature space is more versatile and has shown promising results. Nonetheless, feature semantics is seldom considered and existing feature augmentation methods suffer from a limited variety of augmented features. We decompose features into class-generic, class-specific, domain-generic, and domain-specific components. We propose a cross-domain feature augmentation method named XDomainMix that enables us to increase sample diversity while emphasizing the learning of invariant representations to achieve domain generalization. Experiments on widely used benchmark datasets demonstrate that our proposed method is able to achieve state-of-the-art performance. Quantitative analysis indicates that our feature augmentation approach facilitates the learning of effective models that are invariant across different domains.

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AAAI Conference 2023 Conference Paper

Leveraging Old Knowledge to Continually Learn New Classes in Medical Images

Evelyn Chee
Mong Li Lee
Wynne Hsu

Class-incremental continual learning is a core step towards developing artificial intelligence systems that can continuously adapt to changes in the environment by learning new concepts without forgetting those previously learned. This is especially needed in the medical domain where continually learning from new incoming data is required to classify an expanded set of diseases. In this work, we focus on how old knowledge can be leveraged to learn new classes without catastrophic forgetting. We propose a framework that comprises of two main components: (1) a dynamic architecture with expanding representations to preserve previously learned features and accommodate new features; and (2) a training procedure alternating between two objectives to balance the learning of new features while maintaining the model’s performance on old classes. Experiment results on multiple medical datasets show that our solution is able to achieve superior performance over state-of-the-art baselines in terms of class accuracy and forgetting.

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NeurIPS Conference 2023 Conference Paper

Multi-Object Representation Learning via Feature Connectivity and Object-Centric Regularization

Alex Foo
Wynne Hsu
Mong Li Lee

Discovering object-centric representations from images has the potential to greatly improve the robustness, sample efficiency and interpretability of machine learning algorithms. Current works on multi-object images typically follow a generative approach that optimizes for input reconstruction and fail to scale to real-world datasets despite significant increases in model capacity. We address this limitation by proposing a novel method that leverages feature connectivity to cluster neighboring pixels likely to belong to the same object. We further design two object-centric regularization terms to refine object representations in the latent space, enabling our approach to scale to complex real-world images. Experimental results on simulated, real-world, complex texture and common object images demonstrate a substantial improvement in the quality of discovered objects compared to state-of-the-art methods, as well as the sample efficiency and generalizability of our approach. We also show that the discovered object-centric representations can accurately predict key object properties in downstream tasks, highlighting the potential of our method to advance the field of multi-object representation learning.

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NeurIPS Conference 2023 Conference Paper

REFINE: A Fine-Grained Medication Recommendation System Using Deep Learning and Personalized Drug Interaction Modeling

Suman Bhoi
Mong Li Lee
Wynne Hsu
Ngiap Chuan Tan

Patients with co-morbidities often require multiple medications to manage their conditions. However, existing medication recommendation systems only offer class-level medications and regard all interactions among drugs to have the same level of severity. This limits their ability to provide personalized and safe recommendations tailored to individual needs. In this work, we introduce a deep learning-based fine-grained medication recommendation system called REFINE, which is designed to improve treatment outcomes and minimize adverse drug interactions. In order to better characterize patients’ health conditions, we model the trend in medication dosage titrations and lab test responses, and adapt the vision transformer to obtain effective patient representations. We also model drug interaction severity levels as weighted graphs to learn safe drug combinations and design a balanced loss function to avoid overly conservative recommendations and miss medications that might be needed for certain conditions. Extensive experiments on two real-world datasets show that REFINE outperforms state-of-the-art techniques.

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IJCAI Conference 2022 Conference Paper

Chronic Disease Management with Personalized Lab Test Response Prediction

Suman Bhoi
Mong Li Lee
Wynne Hsu
Hao Sen Andrew Fang
Ngiap Chuan Tan

Chronic disease management involves frequent administration of invasive lab procedures in order for clinicians to determine the best course of treatment regimes for these patients. However, patients are often put off by these invasive lab procedures and do not follow the appointment schedules. This has resulted in poor management of their chronic conditions leading to unnecessary disease complications. An AI system that is able to personalize the prediction of individual patient lab test responses will enable clinicians to titrate the medications to achieve the desired therapeutic outcome. Accurate prediction of lab test response is a challenge because these patients typically have co-morbidities and their treatments might influence the target lab test response. To address this, we model the complex interactions among different medications, diseases, lab test response, and fine-grained dosage information to learn a strong patient representation. Together with information from similar patients and external knowledge such as drug-lab interactions and diagnosis-lab interaction, we design a system called KALP to perform personalized prediction of patients’ response for a target lab result and identify the top influencing factors for the prediction. Experiment results on real-world datasets demonstrate the effectiveness of KALP in reducing prediction errors by a significant margin. Case studies show that the identified factors are consistent with clinicians’ understanding.

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NeurIPS Conference 2021 Conference Paper

Explanation-based Data Augmentation for Image Classification

Sandareka Wickramanayake
Wynne Hsu
Mong Li Lee

Existing works have generated explanations for deep neural network decisions to provide insights into model behavior. We observe that these explanations can also be used to identify concepts that caused misclassifications. This allows us to understand the possible limitations of the dataset used to train the model, particularly the under-represented regions in the dataset. This work proposes a framework that utilizes concept-based explanations to automatically augment the dataset with new images that can cover these under-represented regions to improve the model performance. The framework is able to use the explanations generated by both interpretable classifiers and post-hoc explanations from black-box classifiers. Experiment results demonstrate that the proposed approach improves the accuracy of classifiers compared to state-of-the-art augmentation strategies.

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NeurIPS Conference 2020 Conference Paper

Towards Maximizing the Representation Gap between In-Domain & Out-of-Distribution Examples

Jay Nandy
Wynne Hsu
Mong Li Lee

Among existing uncertainty estimation approaches, Dirichlet Prior Network (DPN) distinctly models different predictive uncertainty types. However, for in-domain examples with high data uncertainties among multiple classes, even a DPN model often produces indistinguishable representations from the out-of-distribution (OOD) examples, compromising their OOD detection performance. We address this shortcoming by proposing a novel loss function for DPN to maximize the representation gap between in-domain and OOD examples. Experimental results demonstrate that our proposed approach consistently improves OOD detection performance.

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AAAI Conference 2019 Conference Paper

FLEX: Faithful Linguistic Explanations for Neural Net Based Model Decisions

Sandareka Wickramanayake
Wynne Hsu
Mong Li Lee

Explaining the decisions of a Deep Learning Network is imperative to safeguard end-user trust. Such explanations must be intuitive, descriptive, and faithfully explain why a model makes its decisions. In this work, we propose a framework called FLEX (Faithful Linguistic EXplanations) that generates post-hoc linguistic justifications to rationalize the decision of a Convolutional Neural Network. FLEX explains a model’s decision in terms of features that are responsible for the decision. We derive a novel way to associate such features to words, and introduce a new decision-relevance metric that measures the faithfulness of an explanation to a model’s reasoning. Experiment results on two benchmark datasets demonstrate that the proposed framework can generate discriminative and faithful explanations compared to state-ofthe-art explanation generators. We also show how FLEX can generate explanations for images of unseen classes as well as automatically annotate objects in images.

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IJCAI Conference 2017 Conference Paper

Quantifying Aspect Bias in Ordinal Ratings using a Bayesian Approach

Lahari Poddar
Wynne Hsu
Mong Li Lee

User opinions expressed in the form of ratings can influence an individual's view of an item. However, the true quality of an item is often obfuscated by user biases, and it is not obvious from the observed ratings the importance different users place on different aspects of an item. We propose a probabilistic modeling of the observed aspect ratings to infer (i) each user's aspect bias and (ii) latent intrinsic quality of an item. We model multi-aspect ratings as ordered discrete data and encode the dependency between different aspects by using a latent Gaussian structure. We handle the Gaussian-Categorical non-conjugacy using a stick-breaking formulation coupled with P\'{o}lya-Gamma auxiliary variable augmentation for a simple, fully Bayesian inference. On two real world datasets, we demonstrate the predictive ability of our model and its effectiveness in learning explainable user biases to provide insights towards a more reliable product quality estimation.

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AAMAS Conference 2012 Conference Paper

Coordination Guided Reinforcement Learning

Qiangfeng Peter Lau
Mong Li Lee
Wynne Hsu

In this paper, we propose to guide reinforcement learning (RL) with expert coordination knowledge for multi-agent problems managed by a central controller. The aim is to learn to use expert coordination knowledge to restrict the joint action space and to direct exploration towards more promising states, thereby improving the overall learning rate. We model such coordination knowledge as constraints and propose a two-level RL system that utilizes these constraints for online applications. Our declarative approach towards specifying coordination in multi-agent learning allows knowledge sharing between constraints and features (basis functions) for function approximation. Results on a soccer game and a tactical real-time strategy game show that coordination constraints improve the learning rate compared to using only unary constraints. The two-level RL system also outperforms existing single-level approach that utilizes joint action selection via coordination graphs.

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AIIM Journal 2005 Journal Article

Discovering reliable protein interactions from high-throughput experimental data using network topology

Jin Chen
Wynne Hsu
Mong Li Lee
See-Kiong Ng

Objective: Current protein–protein interaction (PPI) detection via high-throughput experimental methods, such as yeast-two-hybrid has been reported to be highly erroneous, leading to potentially costly spurious discoveries. This work introduces a novel measure called IRAP, i. e. “interaction reliability by alternative path”, for assessing the reliability of protein interactions based on the underlying topology of the PPI network. Methods and materials: A candidate PPI is considered to be reliable if it is involved in a closed loop in which the alternative path of interactions between the two interacting proteins is strong. We devise an algorithm called AlternativePathFinder to compute the IRAP value for each interaction in a complex PPI network. Validation of the IRAP as a measure for assessing the reliability of PPIs is performed with extensive experiments on yeast PPI data. All the data used in our experiments can be downloaded from our supplementary data web site at http: //www. comp. nus. edu. sg/∼chenjin/data. html. Results: Results show consistently that IRAP measure is an effective way for discovering reliable PPIs in large datasets of error-prone experimentally-derived PPIs. Results also indicate that IRAP is better than IG2, and markedly better than the more simplistic IG1 measure. Conclusion: Experimental results demonstrate that a global, system-wide approach—such as IRAP that considers the entire interaction network instead of merely local neighbors—is a much more promising approach for assessing the reliability of PPIs.

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IS Journal 2004 Journal Article

Cleaning the spurious links in data

Mong Li Lee
W. Hsu
Vijay Kothari

Data quality problems can arise from abbreviations, data entry mistakes, duplicate records, missing fields, and many other sources. These problems proliferate when you integrate multiple data sources in data warehousing, federated databases, and global information systems. A newly discovered class of erroneous data is spurious links, where a real-world entity has multiple links that might not be properly associated with it. The existence of such spurious links often leads to confusion and misrepresentation in the data records representing the entity. Although the data set is well known for its high-quality bibliographic information, collecting and maintaining the data from diverse sources requires enormous effort. Errors, including spurious links, are inevitable. To solve this problem, we use context information to identify spurious links. First, we identify data records that contain potential spurious links. We then determine the set of attributes that constitute each record's context. Experiments with three real-world databases have demonstrated that our approach can accurately identify spurious links. Comparing context information between data records can help solve the data quality problem of spurious links-that is, multiple links between data entries and real-world entities.

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