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Main Authors: Suresh, Tarun, Wadhwa, Nalin, Banerjee, Debangshu, Singh, Gagandeep
Format: Preprint
Published: 2025
Subjects:
Online Access:https://arxiv.org/abs/2512.05439
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author Suresh, Tarun
Wadhwa, Nalin
Banerjee, Debangshu
Singh, Gagandeep
author_facet Suresh, Tarun
Wadhwa, Nalin
Banerjee, Debangshu
Singh, Gagandeep
contents As large language models (LLMs) transition from research prototypes to production systems, practitioners often need reliable methods to verify model outputs and characterize tail risk for safe deployment. While sampling-based estimates provide an ad-hoc intuition of model behavior, they offer no sound guarantees. We present BEAVER, the first practical framework for computing deterministic, sound probability bounds on LLM satisfaction of safety properties. Given a prompt & any safety property, BEAVER systematically explores the model output space using novel Token trie and Frontier data structures, maintaining provably sound bounds at every iteration. We formalize the verification problem, prove soundness of our approach, and evaluate BEAVER on 4 safety properties across 12 open-weight LLMs. BEAVER identifies 2-3x more risky instances compared to baselines while taking 1/10 of the compute budget, surfacing tail risks that loose bounds and ad-hoc evaluation misses.
format Preprint
id arxiv_https___arxiv_org_abs_2512_05439
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle BEAVER: An Efficient Deterministic LLM Verifier
Suresh, Tarun
Wadhwa, Nalin
Banerjee, Debangshu
Singh, Gagandeep
Artificial Intelligence
Formal Languages and Automata Theory
As large language models (LLMs) transition from research prototypes to production systems, practitioners often need reliable methods to verify model outputs and characterize tail risk for safe deployment. While sampling-based estimates provide an ad-hoc intuition of model behavior, they offer no sound guarantees. We present BEAVER, the first practical framework for computing deterministic, sound probability bounds on LLM satisfaction of safety properties. Given a prompt & any safety property, BEAVER systematically explores the model output space using novel Token trie and Frontier data structures, maintaining provably sound bounds at every iteration. We formalize the verification problem, prove soundness of our approach, and evaluate BEAVER on 4 safety properties across 12 open-weight LLMs. BEAVER identifies 2-3x more risky instances compared to baselines while taking 1/10 of the compute budget, surfacing tail risks that loose bounds and ad-hoc evaluation misses.
title BEAVER: An Efficient Deterministic LLM Verifier
topic Artificial Intelligence
Formal Languages and Automata Theory
url https://arxiv.org/abs/2512.05439