Tung Duy Vu

Author directory

Also published as: Tung D. Vu


2026

Designing effective heuristics for NP-hard combinatorial optimization problems remains challenging and often requires substantial domain expertise. Recent LLM-guided evolutionary methods have shown promise for automated heuristic generation, but most existing approaches refine heuristics independently or through limited pairwise feedback. We propose **ReVEL**: Multi-Turn Reflective LLM-Guided Heuristic Evolution via Structured Performance Feedback, a framework for group-wise multi-turn heuristic refinement. ReVEL organizes heuristics into behavior-aware reflective groups, including similarity-driven groups for localized refinement and diversity-driven groups for exploratory search. Within each group, the LLM performs iterative multi-turn refinement using accumulated performance feedback, enabling related heuristics to be jointly analyzed and progressively improved across evolutionary iterations. Experiments on standard combinatorial optimization benchmarks show that ReVEL generally improves optimization performance over existing LLM-guided evolutionary baselines across multiple settings and LLM backbones. Additional analyses suggest that behavior-aware grouping contributes to more consistent refinement trajectories during iterative heuristic evolution.
Streaming Automatic Speech Recognition (ASR), also known as online or real-time ASR, transcribes speech incrementally while audio is being spoken and is critical for many industry applications. Despite the strong performance of modern offline ASR models, streaming deployment remains challenging because limited future context can cause early recognition errors to propagate across later chunks. We define the task of streaming ASR error correction and propose StreamCorrect, a modular framework that fine-tunes a lightweight error corrector from self-generated streaming ASR errors and integrates it with existing streaming ASR systems. To enable training without human annotation, StreamCorrect introduces a timestamp-free boundary recovery procedure based on Prefix-to-Reference Alignment for generating chunk-level correction data. Across multiple languages and ASR backbones, StreamCorrect achieves up to 39% relative character error rate (CER) reduction with minimal latency overhead. Error propagation analysis further shows increasing benefits over time, with up to 7.2% absolute CER reduction in later audio chunks. StreamCorrect bridges offline ASR models and streaming deployment through a lightweight correction plug-in while preserving the pretrained ASR component without additional tuning or distillation.
Specifications are vital for ensuring program correctness, yet writing them manually remains challenging and time-intensive. Recent large language model (LLM)-based methods have shown successes in generating specifications such as postconditions, but existing single-pass prompting often yields inaccurate results. In this paper, we present SpecMind, a novel framework for postcondition generation that treats LLMs as interactive and exploratory reasoners rather than one-shot generators. SpecMind employs feedback-driven multi-turn prompting approaches, enabling the model to iteratively refine candidate postconditions by incorporating implicit and explicit correctness feedback, while autonomously deciding when to stop. This process fosters deeper code comprehension and improves alignment with true program behavior via exploratory attempts. Our empirical evaluation shows that SpecMind significantly outperforms state-of-the-art approaches in both accuracy and completeness of generated postconditions.