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Wai Lam

60 accepted papers

2026

From Abstract to Contextual: What LLMs Still Cannot Do in Mathematics

ICLR 2026poster

Large language models now solve many benchmark math problems at near‑expert levels, yet this progress has not fully translated into reliable performance in real‑world applications. We study this gap through contextual mathematical reasoning, where the mathematical core must be formulated from descri…

Cited by 0SourceScholar
2026

HGMem: Hypergraph-based Working Memory to Improve Multi-step RAG for Long-Context Complex Relational Modeling

ICML 2026poster

Multi-step retrieval-augmented generation (RAG) has become a widely adopted strategy for enhancing large language models (LLMs) on tasks that demand global comprehension and intensive reasoning. Although many RAG systems incorporate a working memory to consolidate information, existing designs prima…

Cited by 0SourceScholar
2025

Harnessing Webpage UIs for Text-Rich Visual Understanding

ICLR 2025poster

Text-rich visual understanding—the ability to interpret both textual content and visual elements within a scene—is crucial for multimodal large language models (MLLMs) to effectively interact with structured environments. We propose leveraging webpage UIs as a naturally structured and diverse data s…

Cited by 3SourcePDFScholar
2025

InfiniteICL: Breaking the Limit of Context Window Size via Long Short-term Memory Transformation

ACL 2025finding

In-context learning (ICL) is critical for large language models (LLMs), but its effectiveness is constrained by finite context windows, particularly in ultra-long contexts. To overcome this, we introduce **InfiniteICL**, a framework that parallels context and parameters in LLMs with short- and long-…

Cited by 0SourcePDFScholar
2025

JsonTuning: Towards Generalizable, Robust, and Controllable Instruction Tuning

ACL 2025finding

Instruction tuning is vital for enhancing the performance of large language models (LLMs), but existing text-to-text methods, referred to as TextTuning, struggle with issues such as generalization, robustness, and controllability due to their lack of explicit task structures. We introduce JsonTuning…

2025

LLM2: Let Large Language Models Harness System 2 Reasoning

NAACL 2025short

Large language models (LLMs) have exhibited impressive capabilities across a myriad of tasks, yet they occasionally yield undesirable outputs. We posit that these limitations are rooted in the foundational autoregressive architecture of LLMs, which inherently lacks mechanisms for differentiating bet…

2025

LNE-Blocking: An Efficient Framework for Contamination Mitigation Evaluation on Large Language Models

EMNLP 2025

The problem of data contamination is now almost inevitable during the development of large language models (LLMs), with the training data commonly integrating those evaluation benchmarks even unintentionally. This problem subsequently makes it hard to benchmark LLMs fairly. Instead of constructing c

2025

Neuro-Symbolic Integration Brings Causal and Reliable Reasoning Proofs

NAACL 2025findings

Two lines of approaches are adopted for complex reasoning with LLMs. One line of work prompts LLMs with various reasoning structures, while the structural outputs can be naturally regarded as intermediate reasoning steps. Another line of work adopt LLM-free declarative solvers to do the reasoning ta…

2025

SLoW: Select Low-frequency Words! Automatic Dictionary Selection for Translation on Large Language Models

EMNLP 2025

There are more than 7,000 languages around the world, and current Large Language Models (LLMs) only support hundreds of languages. Dictionary-based prompting methods can enhance translation on them, but most methods use all the available dictionaries, which could be expensive. Instead, it will be fl

2025

SWE-Fixer: Training Open-Source LLMs for Effective and Efficient GitHub Issue Resolution

ACL 2025finding

Large Language Models (LLMs) have demonstrated remarkable proficiency across a variety of complex tasks. One significant application of LLMs is in tackling software engineering challenges, particularly in resolving real-world tasks on GitHub by fixing code based on the issues reported by the users.…

2025

SeqPO-SiMT: Sequential Policy Optimization for Simultaneous Machine Translation

ACL 2025finding

We present Sequential Policy Optimization for Simultaneous Machine Translation (SeqPO-SiMT), a new policy optimization framework that defines the simultaneous machine translation (SiMT) task as a sequential decision making problem, incorporating a tailored reward to enhance translation quality while…

2025

Stephanie: Step-by-Step Dialogues for Mimicking Human Interactions in Social Conversations

NAACL 2025findings

In the rapidly evolving field of natural language processing, dialogue systems primarily employ a single-step dialogue paradigm. Although this paradigm is commonly adopted, it lacks the depth and fluidity of human interactions and does not appear natural. We introduce a novel **Step**-by-Step Dialog…

Cited by 2SourcePDFScholar
2025

The Essence of Contextual Understanding in Theory of Mind: A Study on Question Answering with Story Characters

ACL 2025long

Theory-of-Mind (ToM) is a fundamental psychological capability that allows humans to understand and interpret the mental states of others. Humans infer others’ thoughts by integrating causal cues and indirect clues from broad contextual information, often derived from past interactions. In other wor…

Cited by 0SourcePDFScholar
2024

A Frustratingly Simple Decoding Method for Neural Text Generation

COLING 2024main

We introduce a frustratingly simple, highly efficient, and surprisingly effective decoding method, termed Frustratingly Simple Decoding (FSD), for neural text generation. The idea behind FSD is straightforward: We construct an anti-language model (anti-LM) based on previously generated text, which i…

2024

A Thorough Examination of Decoding Methods in the Era of LLMs

EMNLP 2024main

Decoding methods play an indispensable role in converting language models from next-token predictors into practical task solvers. Prior research on decoding methods, primarily focusing on task-specific models, may not extend to the current era of general-purpose large language models (LLMs). Moreove…

2024

CO3: Low-resource Contrastive Co-training for Generative Conversational Query Rewrite

COLING 2024main

Generative query rewrite generates reconstructed query rewrites using the conversation history while rely heavily on gold rewrite pairs that are expensive to obtain. Recently, few-shot learning is gaining increasing popularity for this task, whereas these methods are sensitive to the inherent noise…

Cited by 0SourcePDFScholar
2024

Chain-of-Dictionary Prompting Elicits Translation in Large Language Models

EMNLP 2024main

Large language models (LLMs) have shown surprisingly good performance in multilingual neural machine translation (MNMT) even if not being trained explicitly for translation. Yet, they still struggle with translating low-resource languages. As supported by our experiments, a bilingual dictionary betw…

2024

CodeAttack: Revealing Safety Generalization Challenges of Large Language Models via Code Completion

ACL 2024findings

The rapid advancement of Large Language Models (LLMs) has brought about remarkable generative capabilities but also raised concerns about their potential misuse. While strategies like supervised fine-tuning and reinforcement learning from human feedback have enhanced their safety, these methods prim…

2024

Consecutive Batch Model Editing with HooK Layers

EMNLP 2024main

As the typical retraining paradigm is unacceptably time- and resource-consuming, researchers are turning to model editing to find an effective way that supports both consecutive and batch scenarios to edit the model behavior directly. Despite all these practical expectations, existing model editing…

2024

Distributional Inclusion Hypothesis and Quantifications: Probing for Hypernymy in Functional Distributional Semantics

ACL 2024long

Functional Distributional Semantics (FDS) models the meaning of words by truth-conditional functions. This provides a natural representation for hypernymy but no guarantee that it can be learnt when FDS models are trained on a corpus. In this paper, we probe into FDS models and study the representat…

2024

Not All Preference Pairs Are Created Equal: A Recipe for Annotation-Efficient Iterative Preference Learning

EMNLP 2024finding

Iterative preference learning, though yielding superior performances, requires online annotated preference labels. In this work, we study strategies to save annotation budgets while achieving competitive or even better performances for iterative preference learning. Built on intuitions from active l…

2024

On the Worst Prompt Performance of Large Language Models

NeurIPS 2024poster

The performance of large language models (LLMs) is acutely sensitive to the phrasing of prompts, which raises significant concerns about their reliability in real-world scenarios. Existing studies often divide prompts into task-level instructions and case-level inputs and primarily focus on evaluati…

Cited by 8SourcePDFScholar
2024

Plug-and-Play Policy Planner for Large Language Model Powered Dialogue Agents

ICLR 2024poster

Proactive dialogues serve as a practical yet challenging dialogue problem in the era of large language models (LLMs), where the dialogue policy planning is the key to improving the proactivity of LLMs. Most existing studies enable the dialogue policy planning of LLMs using various prompting schemes…

2024

Reasons to Reject? Aligning Language Models with Judgments

ACL 2024findings

As humans, we consistently interact with our peers and receive feedback in the form of natural language. This language feedback allows us to maintain appropriate behavior, and rectify potential errors. The question arises naturally: can we use language feedback to align large language models (LLMs)?…

2024

StrategyLLM: Large Language Models as Strategy Generators, Executors, Optimizers, and Evaluators for Problem Solving

NeurIPS 2024poster

Most existing prompting methods suffer from the issues of generalizability and consistency, as they often rely on instance-specific solutions that may not be applicable to other instances and lack task-level consistency across the selected few-shot examples. To address these limitations, we propose…

2024

Unveiling the Generalization Power of Fine-Tuned Large Language Models

NAACL 2024long

While Large Language Models (LLMs) have demonstrated exceptional multitasking abilities, fine-tuning these models on downstream, domain-specific datasets is often necessary to yield superior performance on test sets compared to their counterparts without fine-tuning. However, the comprehensive effec…

2023

A Survey on Proactive Dialogue Systems: Problems, Methods, and Prospects

IJCAI 2023poster

Proactive dialogue systems, related to a wide range of real-world conversational applications, equip the conversational agent with the capability of leading the conversation direction towards achieving pre-defined targets or fulfilling certain goals from the system side. It is empowered by advanced…

Cited by 44SourcePDFScholar
2023

DepWiGNN: A Depth-wise Graph Neural Network for Multi-hop Spatial Reasoning in Text

EMNLP 2023long findings

Spatial reasoning in text plays a crucial role in various real-world applications. Existing approaches for spatial reasoning typically infer spatial relations from pure text, which overlook the gap between natural language and symbolic structures. Graph neural networks (GNNs) have showcased exceptio…

Cited by 0SourcecodeScholar
2023

Enhancing Grammatical Error Correction Systems with Explanations

ACL 2023long

Grammatical error correction systems improve written communication by detecting and correcting language mistakes. To help language learners better understand why the GEC system makes a certain correction, the causes of errors (evidence words) and the corresponding error types are two key factors. To…

2023

From Cloze to Comprehension: Retrofitting Pre-trained Masked Language Models to Pre-trained Machine Reader

NeurIPS 2023poster

We present Pre-trained Machine Reader (PMR), a novel method for retrofitting pre-trained masked language models (MLMs) to pre-trained machine reading comprehension (MRC) models without acquiring labeled data. PMR can resolve the discrepancy between model pre-training and downstream fine-tuning of ex…

Cited by 4SourcePDFScholar
2023

Knowledge-enhanced Mixed-initiative Dialogue System for Emotional Support Conversations

ACL 2023long

Unlike empathetic dialogues, the system in emotional support conversations (ESC) is expected to not only convey empathy for comforting the help-seeker, but also proactively assist in exploring and addressing their problems during the conversation. In this work, we study the problem of mixed-initiati…

2023

On the Effectiveness of Parameter-Efficient Fine-Tuning

AAAI 2023technical

Fine-tuning pre-trained models has been ubiquitously proven to be effective in a wide range of NLP tasks. However, fine-tuning the whole model is parameter inefficient as it always yields an entirely new model for each task. Currently, many research works propose to only fine-tune a small portion of…

2023

Once Upon a ${\it Time}$ in ${\it Graph}$: Relative-Time Pretraining for Complex Temporal Reasoning

EMNLP 2023long main

Our physical world is constantly evolving over time, rendering challenges for pre-trained language models to understand and reason over the temporal contexts of texts. Existing work focuses on strengthening the direct association between a piece of text and its time-stamp. However, the knowledge-tim…

Cited by 0SourceScholar
2023

PeerDA: Data Augmentation via Modeling Peer Relation for Span Identification Tasks

ACL 2023long

Span identification aims at identifying specific text spans from text input and classifying them into pre-defined categories. Different from previous works that merely leverage the Subordinate (SUB) relation (i.e. if a span is an instance of a certain category) to train models, this paper for the fi…

2023

Progressive Translation: Improving Domain Robustness of Neural Machine Translation with Intermediate Sequences

ACL 2023findings

Previous studies show that intermediate supervision signals benefit various Natural Language Processing tasks. However, it is not clear whether there exist intermediate signals that benefit Neural Machine Translation (NMT). Borrowing techniques from Statistical Machine Translation, we propose interm…

2023

TRIP: Accelerating Document-level Multilingual Pre-training via Triangular Document-level Pre-training on Parallel Data Triplets

EMNLP 2023long findings

Despite the success of multilingual sequence-to-sequence pre-training, most existing approaches rely on document-level monolingual corpora in many different languages, sentence-level bilingual corpora,\footnote{In this paper, we use bilingual corpora to denote parallel corpora with bilingual transla…

Cited by 0SourceScholar
2022

ConReader: Exploring Implicit Relations in Contracts for Contract Clause Extraction

EMNLP 2022main

We study automatic Contract Clause Extraction (CCE) by modeling implicit relations in legal contracts. Existing CCE methods mostly treat contracts as plain text, creating a substantial barrier to understanding contracts of high complexity. In this work, we first comprehensively analyze the complexit…

2022

McQueen: a Benchmark for Multimodal Conversational Query Rewrite

EMNLP 2022main

The task of query rewrite aims to convert an in-context query to its fully-specified version where ellipsis and coreference are completed and referred-back according to the history context. Although much progress has been made, less efforts have been paid to real scenario conversations that involve…

2022

PACIFIC: Towards Proactive Conversational Question Answering over Tabular and Textual Data in Finance

EMNLP 2022main

To facilitate conversational question answering (CQA) over hybrid contexts in finance, we present a new dataset, named PACIFIC. Compared with existing CQA datasets, PACIFIC exhibits three key features: (i) proactivity, (ii) numerical reasoning, and (iii) hybrid context of tables and text. A new task…

2022

Retrofitting Multilingual Sentence Embeddings with Abstract Meaning Representation

EMNLP 2022main

We introduce a new method to improve existing multilingual sentence embeddings with Abstract Meaning Representation (AMR). Compared with the original textual input, AMR is a structured semantic representation that presents the core concepts and relations in a sentence explicitly and unambiguously. I…

2022

Semantic Composition with PSHRG for Derivation Tree Reconstruction from Graph-Based Meaning Representations

ACL 2022long

We introduce a data-driven approach to generating derivation trees from meaning representation graphs with probabilistic synchronous hyperedge replacement grammar (PSHRG). SHRG has been used to produce meaning representation graphs from texts and syntax trees, but little is known about its viability…

2022

Towards Generalizable and Robust Text-to-SQL Parsing

EMNLP 2022finding

Text-to-SQL parsing tackles the problem of mapping natural language questions to executable SQL queries. In practice, text-to-SQL parsers often encounter various challenging scenarios, requiring them to be generalizable and robust. While most existing work addresses a particular generalization or ro…

2022

UniGDD: A Unified Generative Framework for Goal-Oriented Document-Grounded Dialogue

ACL 2022short

The goal-oriented document-grounded dialogue aims at responding to the user query based on the dialogue context and supporting document. Existing studies tackle this problem by decomposing it into two sub-tasks: knowledge identification and response generation. However, such pipeline methods would u…

2021

A Theoretical Analysis of the Repetition Problem in Text Generation

AAAI 2021technical

Text generation tasks, including translation, summarization, language models, and etc. see rapid growth during recent years. Despite the remarkable achievements, the repetition problem has been observed in nearly all text generation models undermining the generation performance extensively. To solve…

2021

Aspect Sentiment Quad Prediction as Paraphrase Generation

EMNLP 2021main

Aspect-based sentiment analysis (ABSA) has been extensively studied in recent years, which typically involves four fundamental sentiment elements, including the aspect category, aspect term, opinion term, and sentiment polarity. Existing studies usually consider the detection of partial sentiment el…

2021

Aspect-based Sentiment Analysis in Question Answering Forums

EMNLP 2021finding

Aspect-based sentiment analysis (ABSA) typically focuses on extracting aspects and predicting their sentiments on individual sentences such as customer reviews. Recently, another kind of opinion sharing platform, namely question answering (QA) forum, has received increasing popularity, which accumul…

2021

Contrastive Representation Learning for Exemplar-Guided Paraphrase Generation

EMNLP 2021finding

Exemplar-Guided Paraphrase Generation (EGPG) aims to generate a target sentence which conforms to the style of the given exemplar while encapsulating the content information of the source sentence. In this paper, we propose a new method with the goal of learning a better representation of the style…

2021

Cross-lingual Aspect-based Sentiment Analysis with Aspect Term Code-Switching

EMNLP 2021main

Many efforts have been made in solving the Aspect-based sentiment analysis (ABSA) task. While most existing studies focus on English texts, handling ABSA in resource-poor languages remains a challenging problem. In this paper, we consider the unsupervised cross-lingual transfer for the ABSA task, wh…

2021

Exploiting Reasoning Chains for Multi-hop Science Question Answering

EMNLP 2021finding

We propose a novel Chain Guided Retriever-reader (CGR) framework to model the reasoning chain for multi-hop Science Question Answering. Our framework is capable of performing explainable reasoning without the need of any corpus-specific annotations, such as the ground-truth reasoning chain, or human…

2021

Multilingual AMR Parsing with Noisy Knowledge Distillation

EMNLP 2021finding

We study multilingual AMR parsing from the perspective of knowledge distillation, where the aim is to learn and improve a multilingual AMR parser by using an existing English parser as its teacher. We constrain our exploration in a strict multilingual setting: there is but one model to parse all dif…

2021

Neural Machine Translation with Monolingual Translation Memory

ACL 2021long

Prior work has proved that Translation Memory (TM) can boost the performance of Neural Machine Translation (NMT). In contrast to existing work that uses bilingual corpus as TM and employs source-side similarity search for memory retrieval, we propose a new framework that uses monolingual memory and…

2021

Towards Generative Aspect-Based Sentiment Analysis

ACL 2021short

Aspect-based sentiment analysis (ABSA) has received increasing attention recently. Most existing work tackles ABSA in a discriminative manner, designing various task-specific classification networks for the prediction. Despite their effectiveness, these methods ignore the rich label semantics in ABS…

2020

Intra-/Inter-Interaction Network with Latent Interaction Modeling for Multi-turn Response Selection

COLING 2020main

Multi-turn response selection has been extensively studied and applied to many real-world applications in recent years. However, current methods typically model the interactions between multi-turn utterances and candidate responses with iterative approaches, which is not practical as the turns of co…

Cited by 1SourcePDFScholar