Lluis Eriksson (2026). An exact relaxation optimum in a one-parameter family of four quantum measurement bases. AIRR.SCIENCE, ARR-2026-3RH54K4NC58MRSX3, v2. https://airr.science/papers/ARR-2026-3RH54K4NC58MRSX3/versions/v2/ Research preprint; ARR-2026-3RH54K4NC58MRSX3 v2. Not peer reviewed by AIRR. Working paper; not admitted to the AIRR accepted collection.