arXiv Computation and Language

Suffix-Constrained Greedy Search Algorithms for Causal Language Models

arXiv AI
Sep 4

RECAST: Expanding the Boundaries of LLMs' Complex Instruction Following with Multi-Constraint Data

RECAST is a new framework that generates datasets with far more constraints per example than existing benchmarks, aiming to push large language models (LLMs) to better follow complex instructions. The authors built RECAST-30K, a 30,000‑instance dataset covering 19 constraint types extracted from real prompt‑response pairs, and showed that fine‑tuning on it improves LLMs’ ability to handle complex tasks without harming general performance. RECAST also provides rule‑based and LLM‑based validators for automatic constraint verification, enabling reward‑based reinforcement learning to further enhance model performance on challenging tasks.

By Zhengkang Guo, Wenhao Liu, Mingchen Xie, Jingwen Xu, Zisu Huang, Muzhao Tian, Jianhan Xu, Yuanzhe Shen, Qi Qian, Muling Wu, Xiaohua Wang, Changze Lv, He-Da Wang, Hu Yao, Xiaoqing Zheng, Xuanjing Huang
arXiv AI
Sep 4

Grammar-Aligned Decoding

The paper introduces Grammar‑Aligned Decoding (GAD), addressing the issue that conventional grammar‑constrained decoding (GCD) can distort a large language model’s probability distribution, yielding grammatical but low‑likelihood outputs. GAD proposes an adaptive sampling method, Approximate Expected Futures (ASAp), which uses prior samples to over‑approximate future grammaticality, ensuring outputs remain both grammatical and faithful to the model’s conditional probabilities. Experiments on code generation and structured NLP tasks demonstrate that ASAp often produces higher‑likelihood outputs than existing GCD techniques while still enforcing the required grammatical constraints.

By Kanghee Park, Jiayu Wang, Taylor Berg-Kirkpatrick, Nadia Polikarpova, Loris D'Antoni
arXiv Computation and Language
Sep 18

Towards Proactive Detection of User-Side Implicit Conflicts in Human-LLM Dialogue

The paper introduces UC-Bench, a human‑annotated benchmark for detecting user‑side implicit conflicts in Human‑LLM dialogue, a problem largely overlooked compared to LLM‑side conflicts. Experiments show current LLMs struggle with these conflicts, especially when they stem from implicit incompatibilities in dialogue history. To address this, the authors propose SynUC, a constraint‑guided data synthesis method that generates a new training set, UC‑Data, which improves performance of lightweight LLMs on UC‑Bench compared to larger general‑purpose models and existing synthesis approaches.

By Jinqiang Wang, Tao Zhu, Huansheng Ning
arXiv Machine Learning
Aug 27

Narcissus: Program Synthesis Using Context-Aware LLM Approximations

Narcissus is a program synthesizer that uses context‑aware large language model (LLM) approximations to guide enumerative search. Unlike prior methods that convert LLM proposals into rule frequencies and lose structural information, Narcissus retains proposals as syntax trees and scores each program expansion based on its surrounding context, ensuring every rule remains reachable. Across five domains and two search backends, it consistently outperforms static guidance and LLM re‑prompting, solving 40% of ARC tasks that raw proposals only solve 13%, all without any LLM calls during search.

By Tilman Hinnerichs, Sebastijan Dumancic, Neil Yorke-Smith