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Haritz Puerto

5 accepted papers

2025

Fine-Tuning on Diverse Reasoning Chains Drives Within-Inference CoT Refinement in LLMs

ACL 2025long

Requiring a large language model (LLM) to generate intermediary reasoning steps, known as Chain of Thought (CoT), has been shown to be an effective way of boosting performance. Previous approaches have focused on generating multiple independent CoTs, combining them through ensembling or other post-h…

2025

Leaky Thoughts: Large Reasoning Models Are Not Private Thinkers

EMNLP 2025

We study privacy leakage in the reasoning traces of large reasoning models used as personal agents which handle sensitive user data. Unlike final outputs, reasoning traces are often assumed to be internal and safe. We challenge this assumption by showing that reasoning traces frequently contain sens

2025

Scaling Up Membership Inference: When and How Attacks Succeed on Large Language Models

NAACL 2025findings

Membership inference attacks (MIA) attempt to verify the membership of a given data sample in the training set for a model. MIA has become relevant in recent years, following the rapid development of large language models (LLM). Many are concerned about the usage of copyrighted materials for trainin…

2024

Code Prompting Elicits Conditional Reasoning Abilities in Text+Code LLMs

EMNLP 2024main

Reasoning is a fundamental component of language understanding. Recent prompting techniques, such as chain of thought, have consistently improved LLMs’ performance on various reasoning tasks. Nevertheless, there is still little understanding of what triggers reasoning abilities in LLMs in the infere…