Lluis Eriksson (2026). The Exact Five-Level Inverse Commutator Cost: Twelve Horn Chambers, Optimal Rank, and the Sharp 5/2 Resource Tax. AIRR.SCIENCE, ARR-2026-37B8R0QTA894GTFF, v1. https://airr.science/papers/ARR-2026-37B8R0QTA894GTFF/versions/v1/ Archived manuscript; ARR-2026-37B8R0QTA894GTFF v1. Not peer reviewed by AIRR. Historical import; not assessed by AIRR.