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Xiang Hu

14 accepted papers

2026

Understanding and Improving Length Generalization in Hierarchical Sparse Attention Models

ICLR 2026poster

Effectively processing long contexts is a critical challenge for language models. While standard Transformers are limited by quadratic complexity and poor length extrapolation, alternative architectures like sliding window attention and state space models sacrifice the ability to effectively utilize…

Cited by 0SourcecodeScholar
2025

A Systematic Study of Compositional Syntactic Transformer Language Models

ACL 2025long

Syntactic language models (SLMs) enhance Transformers by incorporating syntactic biases through the modeling of linearized syntactic parse trees alongside surface sentences. This paper focuses on compositional SLMs that are based on constituency parse trees and contain explicit bottom-up composition…

2025

Efficient Length-Generalizable Attention via Causal Retrieval for Long-Context Language Modeling

ICML 2025poster

Despite the success of Transformers, handling longer contexts remains challenging due to the limited length generalization and quadratic complexity of self-attention, which often requires post-training with a larger attention window, significantly increasing computational and memory costs. In this p…

Cited by 0SourcePDFScholar
2025

Hardware-aligned Hierarchical Sparse Attention for Efficient Long-term Memory Access

NeurIPS 2025poster

A key advantage of Recurrent Neural Networks (RNNs) over Transformers is their linear computational and space complexity enables faster training and inference for long sequences. However, RNNs are fundamentally unable to randomly access historical context, and simply integrating attention mechanisms…

Cited by 0SourceScholar
2025

NOVA: An Iterative Planning Framework for Enhancing Scientific Innovation with Large Language Models

ACL 2025finding

Scientific innovation is pivotal for humanity, and harnessing large language models (LLMs) to generate research ideas could transform discovery. However, existing LLMs often produce simplistic and repetitive suggestions due to their limited ability in acquiring external knowledge for innovation. To…

2025

Tree-Structured Non-Autoregressive Decoding for Sequence-to-Sequence Text Generation

EMNLP 2025

Autoregressive Transformer (AT) dominates sequence-to-sequence generation tasks but suffers from high inference latency due to sequential token generation. Non-Autoregressive Transformer (NAT) improves inference efficiency by parallelizing token prediction, yet degrades generation quality. To addres

2025

Understanding Parametric and Contextual Knowledge Reconciliation within Large Language Models

NeurIPS 2025spotlight

Retrieval-Augmented Generation (RAG) provides additional contextual knowledge to complement the parametric knowledge in Large Language Models (LLMs). These two knowledge interweave to enhance the accuracy and timeliness of LLM responses. However, the internal mechanisms by which LLMs utilize thes…

Cited by 0SourceScholar
2024

Augmenting Transformers with Recursively Composed Multi-grained Representations

ICLR 2024poster

We present ReCAT, a recursive composition augmented Transformer that is able to explicitly model hierarchical syntactic structures of raw texts without relying on gold trees during both learning and inference. Existing research along this line restricts data to follow a hierarchical tree structure…

2024

Generative Pretrained Structured Transformers: Unsupervised Syntactic Language Models at Scale

ACL 2024long

A syntactic language model (SLM) incrementally generates a sentence with its syntactic tree in a left-to-right manner.We present Generative Pretrained Structured Transformers (GPST), an unsupervised SLM at scale capable of being pre-trained from scratch on raw texts with high parallelism. GPST circu…

2023

A Multi-Grained Self-Interpretable Symbolic-Neural Model For Single/Multi-Labeled Text Classification

ICLR 2023poster

Deep neural networks based on layer-stacking architectures have historically suffered from poor inherent interpretability. Meanwhile, symbolic probabilistic models function with clear interpretability, but how to combine them with neural networks to enhance their performance remains to be explored.…

Cited by 4SourcePDFScholar
2022

Fast-R2D2: A Pretrained Recursive Neural Network based on Pruned CKY for Grammar Induction and Text Representation

EMNLP 2022main

Chart-based models have shown great potential in unsupervised grammar induction, running recursively and hierarchically, but requiring O(n³) time-complexity. The Recursive Transformer based on Differentiable Trees (R2D2) makes it possible to scale to large language model pretraining even with a comp…

2021

R2D2: Recursive Transformer based on Differentiable Tree for Interpretable Hierarchical Language Modeling

ACL 2021long

Human language understanding operates at multiple levels of granularity (e.g., words, phrases, and sentences) with increasing levels of abstraction that can be hierarchically combined. However, existing deep models with stacked layers do not explicitly model any sort of hierarchical process. In this…

2020

Interactive Question Clarification in Dialogue via Reinforcement Learning

COLING 2020industry

Coping with ambiguous questions has been a perennial problem in real-world dialogue systems. Although clarification by asking questions is a common form of human interaction, it is hard to define appropriate questions to elicit more specific intents from a user. In this work, we propose a reinforcem…

Cited by 8SourcePDFScholar