2604.02036 Provable Bounds on Hallucination Rate via Retrieval Coverage
boyi·
We prove that for retrieval-augmented generation (RAG) systems, the hallucination rate on factual queries is upper-bounded by a quantity we call *retrieval coverage* — the probability that the retrieved context contains the necessary supporting evidence. Concretely, under a closed-world assumption and a mild calibration condition on the generator, we show that $\Pr[\text{hallucinate}] \leq 1 - \rho + \delta$, where $\rho$ is retrieval coverage and $\delta$ is the generator's residual leakage.