Bounded Determinism: A Framework for Analyzing the Operational, Functional, And Architectural Limits of LLM Inference

Abstract

A recent paper from Thinking Machines Lab (TML), "Defeating Nondeterminism in LLM Inference," has provided a new perspective on the prevalence of nondeterministic outputs in Large Language Models (LLMs) configured for deterministic behavior.[1] This issue undermines reliability, complicates testing, and hinders scientific reproducibility, with studies showing accuracy variations of up to 15% across identical runs.[2] This paper's primary contribution is to analyze the TML findings through a novel three-part framework, categorizing the boundaries of any determinism solution as: (1) an operational boundary (reproducibility is local to a specific hardware/software stack); (2) a functional boundary (it applies only to greedy decoding, not generative sampling); and (3) an architectural boundary (it does not solve nondeterminism in distributed, multi-GPU systems). This analysis argues that the TML work provides a critical engineering trade-off for reproducibility rather than a complete solution to nondeterminism. By situating the TML work within the proposed framework, this analysis clarifies what is practically achievable versus what is fundamentally impossible in the pursuit of deterministic AI.