Left: zenith angle distribution for the tau-like and non-tau-like events observed in Super-K I to III (173-kton · yr). The shaded region and solid histogram show the fitted tau neutrino contribution and the non-tau atmospheric neutrino interactions, respectively. Right: fit results showing the output of the neural-network analysis for upward-going and downward-going events. Events near NN output = 1 (0) are most tau-like (non-tau-like).
