arXiv Machine Learning

Which Signals of Code Correctness Survive Distribution Shift? Hidden-State and Causal Predictors of Program and Verdict Correctness

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
arXiv Computation and Language
Sep 25

Large Language Models for Programming: Actually Fixing or Reimplementing Incorrect Code?

The paper investigates how large language models (LLMs) handle bug fixing versus problem solving in competitive programming. Using a dataset of ~3,000 Codeforces submissions and their human fixes, the authors compare LLM-generated patches to human patches and assess whether LLMs prefer to modify buggy code or generate new solutions. Results show that LLMs often alter more lines than necessary and sometimes produce entirely new solutions, performing better when allowed to generate solutions from scratch rather than patching existing code.

By Alexandru Stefan Stoica, Traian Rebedea, Marian Cristian Mihaescu
Hugging Face Trending Papers
Sep 24

Large Language Models for Programming: Actually Fixing or Reimplementing Incorrect Code?

The paper investigates how Large Language Models (LLMs) handle bug fixing compared to human-written patches by analyzing about 3,000 Codeforces submissions. It finds that LLMs often modify more lines than necessary and sometimes produce entirely new solutions, and that they solve more problems correctly when generating solutions from scratch rather than patching existing code. The study highlights implications for AI‑assisted programming tools, suggesting a shift toward incremental problem‑solving strategies.

arXiv Machine Learning
Sep 15

Introspective Uncertainty Estimation for LLM-Based Code Generation

The thesis explores Introspective Uncertainty Estimation (IUE) for large language models (LLMs) in code generation, aiming to determine whether hidden-state representations can indicate functional correctness at both response and line levels. Using LiveCodeBench and BigCodeBench, the study finds that hidden states provide a strong signal for overall correctness, with static single-token probes performing best, while dynamic strategies offer no consistent advantage. Although line-level fault localization is more challenging, a conditional Top‑K ranking approach remains effective, suggesting a two‑stage workflow that first screens responses for risk and then prioritizes line‑level checks.

By Thomas Klassert