2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/125195In this paper, adapted from the author's PhD thesis, we present otherwise unpublished results relating to global control schemes, culminating in the calculation of a fault-tolerant threshold for one such scheme. As with early fault-tolerant threshold results, the aim is to calculate a positive number, not to optimise it. We also discuss how the results might affect other related schemes, such as those based on cellular automata.21 pages, 15 figures, 3 tables v2: reference addedQuantum Physicstext