Yewei Song
2026
Are Small Language Models the Silver Bullet to Low-Resource Languages Machine Translation?
Yewei Song | Lujun Li | Cedric Lothritz | Saad Ezzini | Lama Sleem | Niccolo' Gentile | Radu State | Tegawendé F. Bissyandé | Jacques Klein
Proceedings for the Ninth Workshop on Technologies for Machine Translation of Low Resource Languages (LoResMT 2026)
Yewei Song | Lujun Li | Cedric Lothritz | Saad Ezzini | Lama Sleem | Niccolo' Gentile | Radu State | Tegawendé F. Bissyandé | Jacques Klein
Proceedings for the Ninth Workshop on Technologies for Machine Translation of Low Resource Languages (LoResMT 2026)
Small language models (SLMs) offer computationally efficient alternatives to large language models, yet their translation quality for low-resource languages (LRLs) remains severely limited. This work presents the first large-scale evaluation of SLMs across 200 languages, revealing systematic underperformance in LRLs and identifying key sources of linguistic disparity. We show that knowledge distillation from strong teacher models using predominantly monolingual LRL data substantially boosts SLM translation quality—often enabling 2B–3B models to match or surpass systems up to 70B parameters. Our study highlights three core findings: (1) a comprehensive benchmark exposing the limitations of SLMs on 200 languages; (2) evidence that LRL-focused distillation improves translation without inducing catastrophic forgetting, with full-parameter fine-tuning and decoder-only teachers outperforming LoRA and encoder–decoder approaches; and (3) consistent cross-lingual gains demonstrating the scalability and robustness of the method. These results establish an effective, low-cost pathway for improving LRL translation and provide practical guidance for deploying SLMs in truly low-resource settings.
2025
SynFix: Dependency-Aware Program Repair via RelationGraph Analysis
Xunzhu Tang | Jiechao Gao | Jin Xu | Tiezhu Sun | Yewei Song | Saad Ezzini | Wendkûuni C. Ouédraogo | Jacques Klein | Tegawendé F. Bissyandé
Findings of the Association for Computational Linguistics: ACL 2025
Xunzhu Tang | Jiechao Gao | Jin Xu | Tiezhu Sun | Yewei Song | Saad Ezzini | Wendkûuni C. Ouédraogo | Jacques Klein | Tegawendé F. Bissyandé
Findings of the Association for Computational Linguistics: ACL 2025
Recent advancements in large language models (LLMs) have significantly improved software development automation, including bug localization, code synthesis, program repair, and test generation. However, most prior work on program repair focuses on isolated elements, such as classes or functions, neglecting their interdependencies, which limits repair accuracy. We present SynFix, a RelationGraph-based approach that integrates LLMs with structural search and synchronization techniques for coordinated program repair across codebases. SynFix constructs a RelationGraph to capture relationships among classes, functions, variables, and their interactions (e.g., imports, inheritance, dependencies). Each RelationGraph node includes detailed code descriptions to help LLMs understand root causes and retrieve relevant contexts. By analyzing one-hop nodes in the RelationGraph, SynFixensures repairs account for dependent updates across components. Patch validation is conducted using regression tests from the SWE-bench benchmark suite. Evaluated on SWE-bench datasets, SynFix resolves 52.33% of issues in SWE-bench-lite (300 GitHub issues), 55.8% in SWE-bench-verified (500 issues), and 29.86% in SWE-bench-full (2,294 issues), outperforming baselines such as Swe-Agent, Agentless and AutoCodeRover. The codebase is available at https://anonymous.4open.science/r/AutoFix-EC86/.
2024
Revisiting Code Similarity Evaluation with Abstract Syntax Tree Edit Distance
Yewei Song | Cedric Lothritz | Daniel Tang | Tegawendé Bissyandé | Jacques Klein
Proceedings of the 62nd Annual Meeting of the Association for Computational Linguistics (Volume 2: Short Papers)
Yewei Song | Cedric Lothritz | Daniel Tang | Tegawendé Bissyandé | Jacques Klein
Proceedings of the 62nd Annual Meeting of the Association for Computational Linguistics (Volume 2: Short Papers)
This paper revisits recent code similarity evaluation metrics, particularly focusing on the application of Abstract Syntax Tree (AST) editing distance in diverse programming languages. In particular, we explore the usefulness of these metrics and compare them to traditional sequence similarity metrics. Our experiments showcase the effectiveness of AST editing distance in capturing intricate code structures, revealing a high correlation with established metrics. Furthermore, we explore the strengths and weaknesses of AST editing distance and prompt-based GPT similarity scores in comparison to BLEU score, execution match, and Jaccard Similarity. We propose, optimize, and publish an adaptable metric that demonstrates effectiveness across all tested languages, representing an enhanced version of Tree Similarity of Edit Distance (TSED).
CodeAgent: Autonomous Communicative Agents for Code Review
Xunzhu Tang | Kisub Kim | Yewei Song | Cedric Lothritz | Bei Li | Saad Ezzini | Haoye Tian | Jacques Klein | Tegawendé F. Bissyandé
Proceedings of the 2024 Conference on Empirical Methods in Natural Language Processing
Xunzhu Tang | Kisub Kim | Yewei Song | Cedric Lothritz | Bei Li | Saad Ezzini | Haoye Tian | Jacques Klein | Tegawendé F. Bissyandé
Proceedings of the 2024 Conference on Empirical Methods in Natural Language Processing
Code review, which aims at ensuring the overall quality and reliability of software, is a cornerstone of software development. Unfortunately, while crucial, Code review is a labor-intensive process that the research community is looking to automate. Existing automated methods rely on single input-output generative models and thus generally struggle to emulate the collaborative nature of code review. This work introduces CodeAgent, a novel multi-agent Large Language Model (LLM) system for code review automation. CodeAgent incorporates a supervisory agent, QA-Checker, to ensure that all the agents’ contributions address the initial review question. We evaluated CodeAgent on critical code review tasks: (1) detect inconsistencies between code changes and commit messages, (2) identify vulnerability introductions, (3) validate code style adherence, and (4) suggest code revisions. The results demonstrate CodeAgent’s effectiveness, contributing to a new state-of-the-art in code review automation. Our data and code are publicly available (https://github.com/Daniel4SE/codeagent).