# Why Deterministic PRM Guidance Underperforms in Discrete Diffusion Reasoning > Source: > Published: 2026-09-29 06:00:02+00:00 Discrete diffusion language models (dLLMs) expose a denoised solution at every step, which makes process reward model (PRM) guidance look like a way to spend compute at test time. We show that once denoising, PRM scoring, and outcome reward model (ORM) scoring are charged in the same budget of forwa