arXiv AI
Aug 26

Evaluating Language Models on Cross-Language Code Functional Equivalence

The paper introduces PolyHuman, a dataset of human-written programs in C++, Java, and Python, to test whether large language models can judge functional equivalence across languages. Using this dataset, the authors evaluate several open-weight and proprietary LLMs, finding that models struggle more with harder problems, show language-specific biases, and rely partly on superficial similarity cues. They also observe run‑to‑run instability in GPT‑o4‑mini, concluding that current LLMs do not reliably capture functional equivalence within or across programming languages.

By Hui Sun, Anderson Uch\^oa, Rohit Gheyi, Wesley K. G. Assun\c{c}\~ao
arXiv Machine Learning
Oct 16

Causal Syntax Circuits in CodeLMs: Budget and Probe Decide What Looks Localised

The paper investigates whether the tendency of code language models to default to Python when no language is specified is driven by a small, identifiable set of internal components. Using a comprehensive pipeline—including ablation, activation patching, greedy circuit extraction, and significance testing—across 55 model-language configurations, the authors find that this preference is large, grows with model size, and persists after instruction tuning. They also show that the apparent localization of this behavior depends heavily on analysis choices such as component budget and probe design, and that interventions can sometimes alter the model’s output.

By Harsh Kumar, Tanmay Shailesh Joshi, Rahul Maity, Anusa Saha