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Jiexi Liu

7 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

Inverse Reinforcement Learning with Dynamic Reward Scaling for LLM Alignment

ICLR 2026poster

Alignment is vital for safely deploying large language models (LLMs). Existing techniques are either reward-based--train a reward model on preference pairs and optimize with reinforcement learning (RL)--or reward-free--directly fine-tune on ranked outputs. Recent research show that well-tuned reward…

Cited by 0SourceScholar
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…

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…

2022

Multiple Instance Learning for Offensive Language Detection

EMNLP 2022finding

Automatic offensive language detection has become a crucial issue in recent years. Existing researches on this topic are usually based on a large amount of data annotated at sentence level to train a robust model. However, sentence-level annotations are expensive in practice as the scenario expands,…

Cited by 5SourcePDFScholar
2021

Robustness Testing of Language Understanding in Task-Oriented Dialog

ACL 2021long

Most language understanding models in task-oriented dialog systems are trained on a small amount of annotated training data, and evaluated in a small set from the same distribution. However, these models can lead to system failure or undesirable output when being exposed to natural language perturba…