arXiv:2606.29054v1 Announce Type: new Abstract: Large language models (LLMs) deployed for structured generation (NER, JSON extraction, QA, and classification) lack formal reliability guarantees, and standard heuristic abstention policies miss user-specified risk targets by 7.5--12.5%. We characterize when conformal risk control (CRC) can certify structured LLM outputs and when it provably cannot. First, we prove an impossibility result: when the base risk (\mu > \alpha), any distribution-free method must abstain on at least ((\mu-\alpha)/(1-\alpha)) examples, yielding a closed-form feasibility
Source: arXiv cs.LG — read the full report at the original publisher.
