Papers by Hang Chen

41 papers
Capability Salience Vector: Fine-grained Alignment of Loss and Capabilities for Downstream Task Scaling Law (2025.acl-long)

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Challenge: Large language models have demonstrated impressive performance across a wide range of tasks, but this achievement comes with the trade-off of significant computational demands.
Approach: They propose a scaling law that decomposes the overall validation loss and assigns different importance weights to tokens to assess a specific meta-capability.
Outcome: The proposed model can predict the loss trending of models across different levels of computation without a gap between validation loss and model's downstream capabilities.
APOLLO: An Optimized Training Approach for Long-form Numerical Reasoning (2024.lrec-main)

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Challenge: Existing methods to generate reasoning programs that ignore the differences between facts treated all facts equally, leading to wrong punishment of programs that differed from the ground truth.
Approach: They propose an optimized training framework for long-form numerical reasoning that incorporates a number-aware negative sampling strategy and consistency-based reinforcement learning to increase execution accuracy.
Outcome: The proposed method improves the performance of long-form numerical reasoning on the FinQA and ConvFinQA leaderboards.
Guided Knowledge Generation with Language Models for Commonsense Reasoning (2024.findings-emnlp)

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Challenge: Large Language Models (LLMs) have achieved notable success in commonsense reasoning tasks, benefiting from extensive world knowledge acquired through extensive pretraining.
Approach: They propose a method to generate knowledge explanations and to automatically assign labels based on the probability of correct answers.
Outcome: The proposed method outperforms baselines on four widely-used commonsense reasoning benchmarks and shows that it can generate high quality knowledge leading to correct answers.
Ask-Before-Detection: Identifying and Mitigating Conformity Bias in LLM-Powered Error Detector for Math Word Problem Solutions (2025.acl-long)

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Challenge: Recent studies have demonstrated the potential of large language models (LLMs) for automatic error detection in math word problems (MWPs).
Approach: They propose a framework that generates adaptive reference solutions using LLMs to enhance error detection by reducing conformity bias in MWPs.
Outcome: The proposed framework mitigates the performance gap between conventional and alternative solutions in MWPs, especially when combined with reasoning-enhancing techniques like chain-of-thought prompting.
SPARD: Self-Paced Curriculum for RL Alignment via Integrating Reward Dynamics and Data Utility (2026.acl-long)

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Challenge: Large Language Models (LLMs) are shifting the focus from single verifiable tasks toward complex, open-ended real-world scenarios.
Approach: They propose a framework that automatically adjusts reward weights and data importance to synchronize learning intent with data utility for optimal performance.
Outcome: The proposed framework improves model capabilities across all domains and scales.
CoBa: Convergence Balancer for Multitask Finetuning of Large Language Models (2024.emnlp-main)

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Challenge: Existing multi-task learning approaches for large language models fall short due to computational intensive or lack of simultaneous task convergence.
Approach: They propose a new multi-task learning approach that dynamically adjusts task weights during the training process, ensuring that the validation loss of all tasks progresses towards convergence at an even pace.
Outcome: The proposed approach improves the performance of large language models by up to 13% compared to the second-best approaches.
Debiasing the Fine-Grained Classification Task in LLMs with Bias-Aware PEFT (2025.acl-long)

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Challenge: Existing methods to mitigate label biases such as retraining, post-hoc adjustment, and parameter-efficient fine-tuning fail to address prediction propensity and discriminative ability biase.
Approach: They propose a bias-aware optimization framework that incorporates two distinct label balance constraints with a PEFT strategy targeting an intermediate layer to mitigate this issue.
Outcome: The proposed approach outperforms or matches the performance of full-parameter fine-tuning and LoRA, achieving superior results with lower perplexity.
Sentiment-Aware Word and Sentence Level Pre-training for Sentiment Analysis (2022.emnlp-main)

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Challenge: Existing pre-trained language representation models (PLMs) capture sentiment information from word-level while under-considering sentence-level information.
Approach: They propose a Sentiment-aware pre-trained language model with combined Word-level and Sentence-level Pre-training tasks that enhance the PLM’s knowledge about sentiment words.
Outcome: The proposed model achieves state-of-the-art on various sentence-level and aspect-level sentiment classification benchmarks.
BiKT: Enabling Bidirectional Knowledge Transfer Between Pretrained Models and Sequential Downstream Tasks (2024.findings-emnlp)

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Challenge: Existing frameworks adapt from initial pretrained model to each downstream task directly, but ignore sequential nature of downstream tasks and feedback effect on pretrained models.
Approach: They propose a framework to enable bidirectional knowledge transfer between pretrained models and downstream tasks in rounds.
Outcome: The proposed framework improves on 9 GLUE datasets and 6 SuperGLUEs.
Document-Level Relation Extraction via Pair-Aware and Entity-Enhanced Representation Learning (2022.coling-1)

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Challenge: Existing document-level relation extraction methods are sparse in relational entity pairs and the representation of entity pairs is insufficient.
Approach: They propose a Pair-Aware and Entity-Enhanced(PAEE) model to solve two challenges . they propose predicting potential relational entity pairs and assembling directional entity pairs .
Outcome: The proposed model can obtain state-of-the-art performance on four benchmark datasets . it can predict potential relational entity pairs and assemble directional entity pairs .
How to Enhance Causal Discrimination of Utterances: A Case on Affective Reasoning (2023.emnlp-main)

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Challenge: Existing models excel at capturing semantic correlations within utterance embeddings but fail to determine specific causal relationships.
Approach: They propose to incorporate i.i.d. noise terms into conversation process to build a structural causal model . they propose to use unstructured conversation data to facilitate deep learning .
Outcome: The proposed approach can be implemented in unstructured conversation data and a synthetic dataset that includes i.i.d. noise.
Collective Event Detection via a Hierarchical and Bias Tagging Networks with Gated Multi-level Attention Mechanisms (D18-1)

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Challenge: Existing approaches to ACE event detection treat multiple events in one sentence as independent ones and recognize them separately.
Approach: They propose a hierarchical and bias tagging network framework to detect multiple events in one sentence collectively and a gated multi-level attention mechanism to automatically extract and fuse the sentence-level and document-level information.
Outcome: The proposed framework outperforms state-of-the-art methods on a 2005 ACE dataset.
DCFEE: A Document-level Chinese Financial Event Extraction System based on Automatically Labeled Training Data (P18-4)

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Challenge: Existing methods to extract events from documents are limited due to the high cost of labeling . Experimental results demonstrate the effectiveness of a document-level Chinese financial event extraction system.
Approach: They propose a document-level Chinese financial event extraction framework which detects event mentions and extracts events from financial news.
Outcome: The proposed system detects event mentions and extracts events from financial news . it can generate large scale labeled data and extract events from entire document .
Quantifying Semantic Emergence in Language Models (2025.acl-long)

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Challenge: Existing evaluation methods for large language models (LLMs) focus on coarse-grained text, not providing interpretations for the behavior of finergrained tokens.
Approach: They propose a quantitative metric to measure large language models’ ability to extract semantics from input tokens.
Outcome: The proposed metric compares the entropy reduction observed for a sequence of tokens and individual tokens.
Guardian-as-an-Advisor: Advancing Next-Generation Guardian Models for Trustworthy LLMs (2026.findings-acl)

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Challenge: prevailing taxonomies neglect robustness and honesty, yielding safer-on-paper but less useful systems.
Approach: They propose a soft-gating pipeline where a guardian predicts a binary risk label plus a concise explanation and prepends this advice to the original query for re-inference.
Outcome: The proposed model maintains safety while reducing over-refusal.
UBench: Benchmarking Uncertainty in Large Language Models with Multiple Choice Questions (2025.findings-acl)

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Challenge: Existing methods for benchmarking the uncertainty of large language models face challenges . existing methods require internal model access, additional training, or high computational costs .
Approach: They propose a new benchmark for evaluating the uncertainty of large language models based on confidence intervals . UBench encompasses 11,978 multiple choice questions spanning knowledge, language, understanding, and reasoning capabilities.
Outcome: The proposed method outperforms existing methods for benchmarking the uncertainty of large language models.
DRAGON: Domain-specific Robust Automatic Data Generation for RAG Optimization (2026.findings-eacl)

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Challenge: Existing retrieval-augmented generation paradigms rely heavily on public knowledge . Existing RAGs reliant on public information and often falter when faced with domain-specific queries.
Approach: They propose a framework that combines a data-construction modeling approach with a scalable synthetic data-generation pipeline to optimize domain-specific retrieval performance.
Outcome: The proposed framework optimizes domain-specific retrieval performance and bolsters retriever robustness.
HICD: Hallucination-Inducing via Attention Dispersion for Contrastive Decoding to Mitigate Hallucinations in Large Language Models (2025.findings-acl)

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Challenge: Large Language Models (LLMs) often generate hallucinations, producing outputs that are contextually inaccurate or factually incorrect.
Approach: They propose a method that selects attention heads crucial to the model's prediction as inducing heads and induces hallucinations by dispersing attention of these inducers.
Outcome: The proposed method significantly improves performance on tasks requiring contextual faithfulness, reading comprehension, and question answering.
AutoBreach: Universal and Adaptive Jailbreaking with Efficient Wordplay-Guided Optimization via Multi-LLMs (2025.findings-naacl)

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Challenge: Existing jailbreak research exhibits limitations in universality, validity, and efficiency . Existing methods for jailbreaking LLMs have limited validity and effectiveness .
Approach: They propose a black-box approach that uses wordplay-guided mapping rule sampling to create universal adversarial prompts.
Outcome: The proposed method efficiently identifies security vulnerabilities across various LLMs, achieving an average success rate of over 80% with fewer than 10 queries.
LEDGER: Scaling Agentic Document Editing with Dependency-aware Graph Retrieval (2026.findings-acl)

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Challenge: Document editing requires full-context awareness of dependencies, but processing entire documents for each edit incurs prohibitive token costs and latency.
Approach: a framework that constructs lightweight dependency graphs captures semantic relationships and structural hierarchies across document elements is proposed for agentic document editing . a scaLing agentic agentic framework is based on a dependency graph framework that captures dependencies and refactors function dependencies.
Outcome: a new framework achieves 76 consistency versus 56 baseline while reducing token usage by 85 . the framework is based on a framework that captures semantic relationships and structural hierarchies across document elements . it can be used to improve document consistency, but it also reduces token costs and latency .
What are the Essential Factors in Crafting Effective Long Context Multi-Hop Instruction Datasets? Insights and Best Practices (2025.acl-long)

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Challenge: Existing methods to generate long-context instruction-tuning data are limited by poor quality and fewer than 35% of samples are multi-hop .
Approach: They propose a framework that integrates a quality verification agent, a single-hop question generation agent, and a multi-hop questions merger agent to enhance model performance.
Outcome: The proposed framework significantly improves data quality with high-quality, multi-hop, and diverse data.
What does the language of foods say about us? (D19-62)

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Challenge: Using a dataset of 24 million food-related tweets, we can predict if states in the United States are above the median rates for type 2 diabetes mellitus (T2DM) income, poverty, and education are important factors in predicting T2DM rates, but socioeconomic factors do not capture this information.
Approach: They use a dataset of 24 million food-related tweets to investigate the signal contained in the language of food on social media.
Outcome: The language of food can predict health risks, political orientation, and geographic location, and outperform previous work by 4–18%.
Learning from Emptiness: De-biasing Listwise Rerankers with Content-Agnostic Probability Calibration (2026.acl-short)

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Challenge: Existing methods for listwise reranking exhibit intrinsic position bias . existing methods are constrained by an inherent trade-off between efficiency and flexibility .
Approach: They propose a training-free framework that mechanically decouples positional bias from ranking decisions.
Outcome: a training-free framework decouples position bias from ranking decisions . evaluations show it outperforms training-based methods and outperformed expensive methods .
MLeVLM: Improve Multi-level Progressive Capabilities based on Multimodal Large Language Model for Medical Visual Question Answering (2024.findings-acl)

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Challenge: Existing MVQA models ignore multi-level progressive capabilities due to unspecific data and plain architecture.
Approach: They propose a multi-level visual language model for medical visual question answering (MVQA) which covers multi- level questions and answers as well as reasoning processes from visual clues to semantic cognition.
Outcome: The proposed model outperforms existing medical multimodal large language models on a multi-level instruction dataset and a feature alignment module.
GLGE: A New General Language Generation Evaluation Benchmark (2021.findings-acl)

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Challenge: Multi-task benchmarks focus on a range of Natural Language Understanding (NLU) tasks without considering the Natural Language Generation (NLG) models.
Approach: They propose a multi-task benchmark for evaluating the generalization capabilities of NLG models across eight language generation tasks.
Outcome: The proposed benchmarks are based on GLUE and Su-perGLUE for English and several other languages.
Reconstructing Event Regions for Event Extraction via Graph Attention Networks (2020.aacl-main)

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Challenge: Existing approaches for event extraction focus on sentence-level event extraction, but they lack a broader view of the document context.
Approach: They build graphs with candidate event filler extractions enriched by sentential embeddings as nodes and use graph attention networks to identify event regions in a document and aggregate event information.
Outcome: The proposed method performs well on two languages and shows that it is faster than previous methods.
BFS-Prover: Scalable Best-First Tree Search for LLM-based Automatic Theorem Proving (2025.acl-long)

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Challenge: Existing approaches to theorem proving in large language models rely on value functions and/or Monte Carlo Tree Search (MCTS), but the potential of simpler methods like Best-First Tree Search remains underexplored.
Approach: They propose a scalable expert iteration framework that implements strategic data filtering at each expert iteration round, excluding problems solvable via beam search node expansion to focus on harder cases.
Outcome: The proposed framework achieves a state-of-the-art score of 72.95 on the MiniF2F test set and challenges the perceived necessity of complex tree search methods.
Red Teaming Large Reasoning Models (2026.acl-long)

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Challenge: Large Reasoning Models (LRMs) have emerged as a powerful advancement in multi-step reasoning tasks, but they introduce safety and reliability risks, such as CoT-hijacking and prompt-induced inefficiencies.
Approach: They propose a unified benchmark to assess the trustworthiness of Large Reasoning Models.
Outcome: The proposed benchmark evaluates truthfulness, safety and efficiency on 26 models.
RAPID: Efficient Retrieval-Augmented Long Text Generation with Writing Planning and Information Discovery (2025.findings-acl)

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Challenge: Existing methods for knowledge-intensive long texts struggle with issues like hallucinations, topic incoherence, and significant latency.
Approach: They propose a retrieval-augmented long text generation framework with writing P**lanning and I**nformation to address these challenges.
Outcome: The proposed framework outperforms state-of-the-art methods on a freshWiki-2024 dataset.
Document-level Event Extraction via Parallel Prediction Networks (2021.acl-long)

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Challenge: Document-level event extraction (DEE) is indispensable when events are described throughout a document.
Approach: They propose a document-level event extraction model that can extract structured events from a text in parallel.
Outcome: The proposed model outperforms current state-of-the-art methods on a document-level event extraction task.
Language Model Analysis for Ontology Subsumption Inference (2023.findings-acl)

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Challenge: Existing studies focus on simple, triple-based, relational KBs but omit more sophisticated, logic-based conceptualised KB.
Approach: They propose to use ontology subsumption axioms to probe LMs' knowledge of ontologies by probing datasets from atomic and complex concepts.
Outcome: The proposed methods encode less background knowledge of Subsumption Inference (SI) than traditional Natural Language Inference but can improve on SI significantly when a small number of samples are given.
SeaLLMs - Large Language Models for Southeast Asia (2024.acl-demos)

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Challenge: Existing large language models favor high-resource languages, such as English, at the expense of low-resourced and regional languages.
Approach: They propose a series of language models that specifically focuses on Southeast Asian languages.
Outcome: SeaLLM models outperform ChatGPT-3.5 in non-Latin languages by large margins . linguistic disparity impedes access to state-of-the-art AI technologies for non-English-speaking populations .
DiMo-GUI: Advancing Test-time Scaling in GUI Grounding via Modality-Aware Visual Reasoning (2025.emnlp-main)

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Challenge: DiMo-GUI is a training-free framework for GUI grounding that splits input into textual elements and iconic elements, allowing the model to reason over each modality independently using general-purpose vision-language models.
Approach: They propose a training-free framework for GUI grounding that leverages two core strategies: dynamic visual grounding and modality-aware optimization.
Outcome: The proposed framework splits the input into textual elements and iconic elements, allowing the model to reason over each modality independently using general-purpose vision-language models.
CoPA: Benchmarking Personalized Question Answering with Data-Informed Cognitive Factors (2026.findings-acl)

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Challenge: Existing LLMs rely on surface-level similarity or manual heuristics to evaluate personalization . Existing evaluation protocols for personalization are lacking sufficient data-driven validation.
Approach: They propose a benchmark to assess personalization by mining CIPDs to quantify individual preferences.
Outcome: The proposed benchmark provides a more comprehensive and discriminative standard than generic metrics.
Doc-V*: Coarse-to-Fine Interactive Visual Reasoning for Multi-Page Document VQA (2026.acl-long)

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Challenge: Existing OCR-free approaches to document visual question answering are brittle and passive.
Approach: They propose an OCR-free agentic framework that casts multi-page DocVQA as sequential evidence aggregation.
Outcome: The proposed framework outperforms open-source and proprietary models in five benchmarks and improves out-of-domain performance by 47.9% over baseline.
GA-S3: Comprehensive Social Network Simulation with Group Agents (2025.findings-acl)

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Challenge: Existing social network simulations focus on discrete events or system dynamics instead of elucidating underlying mechanisms or causal relationships.
Approach: They propose a Social network simulation system that leverages newly designed Group Agents to make intelligent decisions regarding various online events.
Outcome: The proposed system can make intelligent decisions regarding online events at a manageable cost.
CoLLiE: Collaborative Training of Large Language Models in an Efficient Way (2023.emnlp-demo)

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Challenge: Large language models (LLMs) are increasingly pivotal in a wide range of tasks . however, the resources required for training these models necessitate efficient solutions .
Approach: They propose a library that facilitates collaborative training of large language models . they use 3D parallelism, parameter-efficient fine-tuning methods and optimizers .
Outcome: The proposed library has proven superior training efficiency in comparison with prevalent solutions in pre-training and fine-tuning scenarios.
CodeRetriever: A Large Scale Contrastive Pre-Training Method for Code Search (2022.emnlp-main)

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Challenge: Existing code pre-training approaches often adopt (masked) language modeling as the training objective which targets on learning to predict (macked) tokens in a given code context.
Approach: They propose a code-text contrastive learning model which learns function-level code semantic representations through large-scale code corpus.
Outcome: The proposed model achieves new state-of-the-art with significant improvement over existing pre-trained models on eleven domain/language-specific code search tasks with six programming languages in different code granularity.
Sparse Progressive Distillation: Resolving Overfitting under Pretrain-and-Finetune Paradigm (2022.acl-long)

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Challenge: Conventional wisdom in pruning Transformer-based language models is that it reduces model expressiveness, but new research shows pruning increases risk of overfitting when performed at the fine-tuning phase.
Approach: They propose to reduce pruning risk under pretrain-and-finetune paradigm . they propose to use knowledge distillation to improve pruning performance .
Outcome: The proposed method outperforms the leading competitors on the GLUE benchmark.
LCO: LLM-based Constraint Optimization for Safer Agentic LLMs in Real-world Tasks (2026.findings-acl)

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Challenge: Existing defense methods are insufficient to address in-context reward hacking (ICRH), where LLMs iteratively optimize their behavior to maximize proxy objectives, resulting in harmful side effects.
Approach: They propose a framework that reduces in-context reward hacking (ICRH) through repeated interactions with the environment.
Outcome: The proposed framework reduces ICRH without model fine-tuning while maintaining task performance.
GoViG: Goal-Conditioned Visual Navigation Instruction Generation via Multimodal Reasoning (2026.findings-acl)

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Challenge: Current methods for instruction generation depend on privileged inputs such as semantic maps, landmark annotations, and panoramic views.
Approach: They propose a task that generates coherent navigation instructions from egocentric visual observations.
Outcome: The proposed task generates coherent navigation instructions from egocentric visual data . the proposed task improves performance over state-of-the-art methods in BLEU-4 and CIDEr scores .

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