Issues in determining alpha_s from hadronic tau decay and   electroproduction data
  We discuss some key issues associated with duality-violating and non-perturbative OPE contributions to the theoretical representations of light quark current-current two-point functions and relevant to precision determinations of alpha_s from hadronic tau decay and electroproduction cross-section data. We demonstrate that analyses with an explicit representation of duality-violating effects are required to bring theoretical errors in such extractions under control, motivating the accompanying paper in these proceedings, which presents the results of such an analysis. 
D. Boito, O. Cata, M. Golterman, M. Jamin, K. Maltman, J. Osborne and   S. Peris
hep-ph hep-ex