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The four-loop determination of the strong coupling from fully inclusive observables is reviewed. Special attention is given to the low-energy measurement extracted from the hadronic τ decay width. A recent exhaustive analysis of the ALEPH data, exploring several complementary methodologies with very different sensitivities to inverse power corrections and duality violations, confirms the strong suppression of non-perturbative contributions to R_τ. It gives the value α_s(m_τ^2)= 0.328 ± 0.013,doi:10.1051/epjconf/201713701016 fatcat:5gyoraci6zffjoeiemlfzc24fe