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Songcan Chen

35 accepted papers

2026

Beyond Observations: Reconstruction Error-Guided Irregularly Sampled Time Series Representation Learning

AAAI 2026technical

Irregularly sampled time series (ISTS), characterized by non-uniform time intervals with natural missingness, are prevalent in real-world applications. Existing approaches for ISTS modeling primarily rely on observed values to impute unobserved ones or infer latent dynamics. However, these methods o

Cited by 0SourcePDFScholar
2026

Continuous Exposure-Time Modeling for Realistic Atmospheric Turbulence Synthesis

CVPR 2026

Atmospheric turbulence significantly degrades long-range imaging by introducing geometric warping and exposure-time-dependent blur, which adversely affects both visual quality and the performance of high-level vision tasks. Existing methods for synthesizing turbulence effects often oversimplify the

Cited by 0SourcecodeScholar
2026

HGLTR: Hierarchical Knowledge Injection for Calibrating Pre-trained Models in Long-Tail Recognition

AAAI 2026technical

Long-tail recognition remains challenging for pre-trained foundation models like CLIP, which often suffer from performance degradation under imbalanced data. This stems not only from the overfitting/underfitting issues during fine-tuning but, more fundamentally, from the inherent bias inherited from

Cited by 0SourcePDFScholar
2026

Online Continual Learning with Dynamic Label Hierarchies

ICML 2026poster

Online Continual Learning (OCL) aims to learn from endless non\text{-}stationary data streams, yet most existing methods assume a flat label space and overlook the hierarchical organization of real\text{-}world concepts that evolves both horizontally (sibling classes) and vertically (coarse or fine …

Cited by 0SourceScholar
2026

Shortcut-Resistant CAM Distillation for Long-Tailed Recognition

ICML 2026poster

Real-world datasets often follow a long-tailed distribution, making generalization to tail classes difficult. We revisit this problem through the lens of shortcut learning, where models prefer the easiest predictive cues (e.g., background or textures) over object-centric semantics, especially under …

Cited by 0SourceScholar
2026

The Finer the Better: Towards Granular-aware Open-set Domain Generalization

AAAI 2026technical

Open-Set Domain Generalization (OSDG) aims to generalize over unseen target domains containing open classes, and the core challenge lies in identifying unknown samples never encountered during training. Recently, CLIP has exhibited impressive performance in OSDG, while it still falls into the dilemm

Cited by 0SourcePDFScholar
2025

Cut out and Replay: A Simple yet Versatile Strategy for Multi-Label Online Continual Learning

ICML 2025poster

Multi-Label Online Continual Learning (MOCL) requires models to learn continuously from endless multi-label data streams, facing complex challenges including persistent catastrophic forgetting, potential missing labels, and uncontrollable imbalanced class distributions. While existing MOCL methods a…

2025

DM-POSA: Enhancing Open-World Test-Time Adaptation with Dual-Mode Matching and Prompt-Based Open Set Adaptation

IJCAI 2025

The need to generalize the pre-trained deep learning models to unknown test-time data distributions has spurred research into test-time adaptation (TTA). Existing studies have mainly focused on closed-set TTA with only covariate shifts, while largely overlooking open-set TTA that involves semantic s

Cited by 0SourcePDFScholar
2025

Enhanced Adaptive Gradient Algorithms for Nonconvex-PL Minimax Optimization

AISTATS 2025poster

Minimax optimization recently is widely applied in many machine learning tasks such as generative adversarial networks, robust learning and reinforcement learning. In the paper, we study a class of nonconvex-nonconcave minimax optimization with nonsmooth regularization, where the objective function…

Cited by 0SourceScholar
2025

Expand Horizon: Graph Out-of-Distribution Generalization via Multi-Level Environment Inference

AAAI 2025technical

Graph neural networks (GNNs) are widely used for node classification tasks, but when encountering distribution shifts due to environmental change in real-world scenarios, they tend to learn unstable correlations between features and labels. To overcome this dilemma, a powerful class of approaches vi…

Cited by 0SourcePDFScholar
2025

LoD: Loss-difference OOD Detection by Intentionally Label-Noisifying Unlabeled Wild Data

IJCAI 2025

Using unlabeled wild data containing both in-distribution (ID) and out-of-distribution (OOD) data to improve the safety and reliability of models has recently received increasing attention. Existing methods either design customized losses for labeled ID and unlabeled wild data then perform joint opt

2025

MLC-NC: Long-Tailed Multi-Label Image Classification Through the Lens of Neural Collapse

AAAI 2025technical

Long-tailed (LT) data distribution is common in multi-label image classification (MLC) and can significantly impact the performance of classification models. One reason is the challenge of learning unbiased instance representations (i.e. features) for imbalanced datasets. Additionally, the co-occurr…

Cited by 0SourcePDFScholar
2025

ProMEA: Prompt-driven Expansion and Alignment for Single Domain Generalization

IJCAI 2025

In single Domain Generalization (single-DG), data scarcity in the single source domain hampers the learning for invariant features, leading to overfitting over source domain and poor generalization to unseen target domains. Existing single-DG methods primarily augment the source domain by adversaria

Cited by 0SourcePDFScholar
2025

TimeCHEAT: A Channel Harmony Strategy for Irregularly Sampled Multivariate Time Series Analysis

AAAI 2025technical

Irregularly sampled multivariate time series (ISMTS) are prevalent in reality. Due to their non-uniform intervals between successive observations and varying sampling rates among series, the channel-independent (CI) strategy, which has been demonstrated more desirable for complete multivariate time…

2025

Unlocking Better Closed-Set Alignment Based on Neural Collapse for Open-Set Recognition

AAAI 2025technical

In recent Open-set Recognition (OSR) community, a prevailing belief is that enhancing the discriminative boundaries of closed-set classes can improve the robustness of Deep Neural Networks (DNNs) against open data during testing. Typical studies validate this *implicitly* by empirical evidence, with…

Cited by 0SourcePDFScholar
2024

Adaptive Federated Minimax Optimization with Lower Complexities

AISTATS 2024poster

Federated learning is a popular distributed and privacy-preserving learning paradigm in machine learning. Recently, some federated learning algorithms have been proposed to solve the distributed minimax problems. However, these federated minimax algorithms still suffer from high gradient or communic…

Cited by 3SourcePDFScholar
2024

Dynamic against Dynamic: An Open-Set Self-Learning Framework

IJCAI 2024poster

In open set recognition, existing methods generally learn statically fixed decision boundaries to reject unknown classes. Though they have achieved promising results, such decision boundaries are evidently insufficient for universal unknown classes in dynamic and open scenarios as they can potential…

2024

Forgetting, Ignorance or Myopia: Revisiting Key Challenges in Online Continual Learning

NeurIPS 2024poster

Online continual learning (OCL) requires the models to learn from constant, endless streams of data. While significant efforts have been made in this field, most were focused on mitigating the \textit{catastrophic forgetting} issue to achieve better classification ability, at the cost of a much heav…

2024

No Regularization Is Needed: Efficient and Effective Incomplete Label Distribution Learning

IJCAI 2024poster

In reality, it is laborious to obtain complete label degrees, giving birth to Incomplete Label Distribution Learning (InLDL), where some degrees are missing. Existing InLDL methods often assume that degrees are uniformly random missing. However, it is often not the case in practice, which arises the…

2024

TimesURL: Self-Supervised Contrastive Learning for Universal Time Series Representation Learning

AAAI 2024technical

Learning universal time series representations applicable to various types of downstream tasks is challenging but valuable in real applications. Recently, researchers have attempted to leverage the success of self-supervised contrastive learning (SSCL) in Computer Vision(CV) and Natural Language Pro…

2024

Unlocking the Power of Open Set: A New Perspective for Open-Set Noisy Label Learning

AAAI 2024technical

Learning from noisy data has attracted much attention, where most methods focus on closed-set label noise. However, a more common scenario in the real world is the presence of both open-set and closed-set noise. Existing methods typically identify and handle these two types of label noise separately…

Cited by 10SourcePDFScholar
2023

ALL-E: Aesthetics-guided Low-light Image Enhancement

IJCAI 2023poster

Evaluating the performance of low-light image enhancement (LLE) is highly subjective, thus making integrating human preferences into image enhancement a necessity. Existing methods fail to consider this and present a series of potentially valid heuristic criteria for training enhancement models. In…

2023

Beyond Myopia: Learning from Positive and Unlabeled Data through Holistic Predictive Trends

NeurIPS 2023spotlight

Learning binary classifiers from positive and unlabeled data (PUL) is vital in many real-world applications, especially when verifying negative examples is difficult. Despite the impressive empirical performance of recent PUL methods, challenges like accumulated errors and increased estimation bias…

2023

Improving Lens Flare Removal with General-Purpose Pipeline and Multiple Light Sources Recovery

ICCV 2023poster

When taking images against strong light sources, the resulting images often contain heterogeneous flare artifacts. These artifacts can importantly affect image visual quality and downstream computer vision tasks. While collecting real data pairs of flare-corrupted/flare-free images for training flar…

Cited by 26PDFcodeScholar
2022

Can Adversarial Training Be Manipulated By Non-Robust Features?

NeurIPS 2022accept

Adversarial training, originally designed to resist test-time adversarial examples, has shown to be promising in mitigating training-time availability attacks. This defense ability, however, is challenged in this paper. We identify a novel threat model named stability attack, which aims to hinder ro…

2022

Reconstruction Enhanced Multi-View Contrastive Learning for Anomaly Detection on Attributed Networks

IJCAI 2022poster

Detecting abnormal nodes from attributed networks is of great importance in many real applications, such as financial fraud detection and cyber security. This task is challenging due to both the complex interactions between the anomalous nodes with other counterparts and their inconsistency in terms…

Cited by 63SourcePDFScholar
2021

Better Safe Than Sorry: Preventing Delusive Adversaries with Adversarial Training

NeurIPS 2021poster

Delusive attacks aim to substantially deteriorate the test accuracy of the learning model by slightly perturbing the features of correctly labeled training examples. By formalizing this malicious attack as finding the worst-case training data within a specific $\infty$-Wasserstein ball, we show that…

2021

Improving Model Robustness by Adaptively Correcting Perturbation Levels with Active Queries

AAAI 2021technical

In addition to high accuracy, robustness is becoming increasingly important for machine learning models in various applications. Recently, much research has been devoted to improving the model robustness by training with noise perturbations. Most existing studies assume a fixed perturbation level fo…

Cited by 13SourcePDFScholar
2019

Faster Stochastic Alternating Direction Method of Multipliers for Nonconvex Optimization

ICML 2019oral

In this paper, we propose a faster stochastic alternating direction method of multipliers (ADMM) for nonconvex optimization by using a new stochastic path-integrated differential estimator (SPIDER), called as SPIDER-ADMM. Moreover, we prove that the SPIDER-ADMM achieves a record-breaking incremental…

Cited by 50SourcePDFScholar