Pengfei Wang
Author directory2026
Every Step Counts: Step-Level Credit Assignment for Tool-Integrated Text-to-SQL
Yaxun Dai | Baolin Sun | Junying Wang | Pengfei Wang | Yingqi Gao | Xuemei Dong | Mengdie Chu | Xiang Qi | Pingfu Chao
Findings of the Association for Computational Linguistics: EMNLP 2026
Yaxun Dai | Baolin Sun | Junying Wang | Pengfei Wang | Yingqi Gao | Xuemei Dong | Mengdie Chu | Xiang Qi | Pingfu Chao
Findings of the Association for Computational Linguistics: EMNLP 2026
Tool-integrated reasoning has emerged as a promising paradigm for Text-to-SQL, framing SQL generation as sequential decision-making interleaved with tool execution. However, existing reinforcement learning approaches rely on coarse-grained outcome supervision, creating a credit assignment problem: models receive identical rewards regardless of whether intermediate steps are redundant or erroneous. We observe that tool-integrated reasoning offers a unique opportunity: each tool invocation produces structured, verifiable outputs that can serve as training-free step-level signals, eliminating the need for expensive reward model training. Building on this insight, we propose FineStep, a step-level credit assignment framework that leverages training-free process rewards derived from tool execution feedback. FineStep constructs a dual-channel value estimate for each step, combining backward-propagated outcome value with forward-smoothed process value, and synthesizes them via group-based normalization into a unified step-level advantage for policy optimization. Experiments on Text-to-SQL benchmarks show that FineStep achieves SOTA performance with a 3.25% EX gain over GRPO at the 4B scale, while results on AIME24 demonstrate transferability beyond SQL.
2025
Diversity-oriented Data Augmentation with Large Language Models
Zaitian Wang | Jinghan Zhang | Xinhao Zhang | Kunpeng Liu | Pengfei Wang | Yuanchun Zhou
Proceedings of the 63rd Annual Meeting of the Association for Computational Linguistics (Volume 1: Long Papers)
Zaitian Wang | Jinghan Zhang | Xinhao Zhang | Kunpeng Liu | Pengfei Wang | Yuanchun Zhou
Proceedings of the 63rd Annual Meeting of the Association for Computational Linguistics (Volume 1: Long Papers)
Data augmentation is an essential technique in natural language processing (NLP) for enriching training datasets by generating diverse samples. This process is crucial for improving the robustness and generalization capabilities of NLP models. However, a significant challenge remains: Insufficient Attention to Sample Distribution Diversity. Most existing methods focus on increasing the sample numbers while neglecting the sample distribution diversity, which can lead to model overfitting. In response, we explore data augmentation’s impact on dataset diversity and propose a Diversity-oriented data Augmentation framework (DoAug). Specifically, we utilize a diversity-oriented fine-tuning approach to train a large language model (LLM) as a diverse paraphraser, which is capable of augmenting textual datasets by generating diversified paraphrases. Then, we apply the LLM paraphraser to a selected coreset of highly informative samples and integrate the paraphrases with the original data to create a more diverse augmented dataset. Finally, we conduct extensive experiments on 12 real-world textual datasets. The results show that our fine-tuned LLM augmenter improves diversity while preserving label consistency, thereby enhancing the robustness and performance of downstream tasks. Specifically, it achieves an average performance gain of 10.52%, surpassing the runner-up baseline with more than three percentage points.
2022
Candidate Soups: Fusing Candidate Results Improves Translation Quality for Non-Autoregressive Translation
Huanran Zheng | Wei Zhu | Pengfei Wang | Xiaoling Wang
Proceedings of the 2022 Conference on Empirical Methods in Natural Language Processing
Huanran Zheng | Wei Zhu | Pengfei Wang | Xiaoling Wang
Proceedings of the 2022 Conference on Empirical Methods in Natural Language Processing
Non-autoregressive translation (NAT) model achieves a much faster inference speed than the autoregressive translation (AT) model because it can simultaneously predict all tokens during inference. However, its translation quality suffers from degradation compared to AT. And existing NAT methods only focus on improving the NAT model’s performance but do not fully utilize it. In this paper, we propose a simple but effective method called “Candidate Soups,” which can obtain high-quality translations while maintaining the inference speed of NAT models. Unlike previous approaches that pick the individual result and discard the remainders, Candidate Soups (CDS) can fully use the valuable information in the different candidate translations through model uncertainty. Extensive experiments on two benchmarks (WMT’14 EN–DE and WMT’16 EN–RO) demonstrate the effectiveness and generality of our proposed method, which can significantly improve the translation quality of various base models. More notably, our best variant outperforms the AT model on three translation tasks with 7.6× speedup.