← Search

Sihao Chen

17 accepted papers

2026

Revela: Dense Retriever Learning via Language Modeling

ICLR 2026oral

Dense retrievers play a vital role in accessing external and specialized knowledge to augment language models (LMs). Training dense retrievers typically requires annotated query-document pairs, which are costly to create and scarce in specialized domains (e.g., code) or in complex settings (e.g., re…

Cited by 0SourcecodeScholar
2025

LogiCoL: Logically-Informed Contrastive Learning for Set-based Dense Retrieval

EMNLP 2025

While significant progress has been made with dual- and bi-encoder dense retrievers, they often struggle on queries with logical connectives, a use case that is often overlooked yet important in downstream applications. Current dense retrievers struggle with such queries, such that the retrieved res

2025

On Reference (In-)Determinacy in Natural Language Inference

NAACL 2025findings

We revisit the reference determinacy (RD) assumption in the task of natural language inference (NLI), i.e., the premise and hypothesis are assumed to refer to the same context when human raters annotate a label. While RD is a practical assumption for constructing a new NLI dataset, we observe that c…

2025

Struct-Bench: A Benchmark for Differentially Private Structured Text Generation

NeurIPS 2025poster

Differentially private (DP) synthetic data generation is a promising technique for utilizing private datasets that otherwise cannot be exposed for model training or other analytics. While much research literature has focused on generating private unstructured text and image data, in enterprise setti…

Cited by 0SourcecodeScholar
2025

Talking Point based Ideological Discourse Analysis in News Events

ACL 2025finding

Analyzing ideological discourse even in the age of LLMs remains a challenge, as these models often struggle to capture the key elements that shape real-world narratives. Specifically, LLMs fail to focus on characteristic elements driving dominant discourses and lack the ability to integrate contextu…

2025

Teaching Language Models To Gather Information Proactively

EMNLP 2025

Large language models (LLMs) are increasingly expected to function as collaborative partners, engaging in back-and-forth dialogue to solve complex, ambiguous problems. However, current LLMs often falter in real-world settings, defaulting to passive responses or narrow clarifications when faced with

2024

Dense X Retrieval: What Retrieval Granularity Should We Use?

EMNLP 2024main

Dense retrieval has become a prominent method to obtain relevant context or world knowledge in open-domain NLP tasks. When we use a learned dense retriever on a retrieval corpus at inference time, an often-overlooked design choice is the retrieval unit in which the corpus is indexed, e.g. document,…

Cited by 63SourcePDFScholar
2024

ExpertQA: Expert-Curated Questions and Attributed Answers

NAACL 2024long

As language models are adopted by a more sophisticated and diverse set of users, the importance of guaranteeing that they provide factually correct information supported by verifiable sources is critical across fields of study. This is especially the case for high-stakes fields, such as medicine and…

2024

Sub-Sentence Encoder: Contrastive Learning of Propositional Semantic Representations

NAACL 2024long

We introduce sub-sentence encoder, a contrastively-learned contextual embedding model for fine-grained semantic representation of text. In contrast to the standard practice with sentence embeddings, where the meaning of an entire sequence of text is encoded into a fixed-length vector, the sub-senten…

2024

The Language Barrier: Dissecting Safety Challenges of LLMs in Multilingual Contexts

ACL 2024findings

As the influence of large language models (LLMs) spans across global communities, their safety challenges in multilingual settings become paramount for alignment research. This paper examines the variations in safety challenges faced by LLMs across different languages and discusses approaches to all…

Cited by 55SourcePDFScholar
2024

The Trickle-down Impact of Reward Inconsistency on RLHF

ICLR 2024poster

Standard practice within Reinforcement Learning from Human Feedback (RLHF) involves optimizing against a Reward Model (RM), which itself is trained to reflect human preferences for desirable generations. A notable subject that is understudied is the (in-)consistency of RMs --- whether they can recog…

2023

PropSegmEnt: A Large-Scale Corpus for Proposition-Level Segmentation and Entailment Recognition

ACL 2023findings

The widely studied task of Natural Language Inference (NLI) requires a system to recognize whether one piece of text is textually entailed by another, i.e. whether the entirety of its meaning can be inferred from the other. In current NLI datasets and models, textual entailment relations are typical…

2023

Using LLM for Improving Key Event Discovery: Temporal-Guided News Stream Clustering with Event Summaries

EMNLP 2023short findings

Understanding and characterizing the discus- sions around key events in news streams is important for analyzing political discourse. In this work, we study the problem of identification of such key events and the news articles associated with those events from news streams. We propose a generic fram…

Cited by 0SourceScholar
2022

Design Challenges for a Multi-Perspective Search Engine

NAACL 2022findings

Many users turn to document retrieval systems (e.g. search engines) to seek answers to controversial or open-ended questions. However, classical document retrieval systems fall short at delivering users a set of direct and diverse responses in such cases, which requires identifying responses within…

2022

Stretching Sentence-pair NLI Models to Reason over Long Documents and Clusters

EMNLP 2022finding

Natural Language Inference (NLI) has been extensively studied by the NLP community as a framework for estimating the semantic relation between sentence pairs. While early work identified certain biases in NLI models, recent advancements in modeling and datasets demonstrated promising performance.In…

2021

Improving Faithfulness in Abstractive Summarization with Contrast Candidate Generation and Selection

NAACL 2021long

Despite significant progress in neural abstractive summarization, recent studies have shown that the current models are prone to generating summaries that are unfaithful to the original context. To address the issue, we study contrast candidate generation and selection as a model-agnostic post-proce…

Cited by 118SourcePDFScholar
2021

MultiOpEd: A Corpus of Multi-Perspective News Editorials

NAACL 2021long

We propose MultiOpEd, an open-domain news editorial corpus that supports various tasks pertaining to the argumentation structure in news editorials, focusing on automatic perspective discovery. News editorial is a genre of persuasive text, where the argumentation structure is usually implicit. Howev…