Determining Majorana Nature of Neutrino from Nucleon Decays and n-nbar oscillations

We show that discovery of baryon number violation in two processes with at least one obeying the selection rule \Delta (B-L) = \pm 2 can determine the Majorana character of neutrinos. Thus observing p \to e^+ \pi^0 and n \to e^- \pi^0 decays, or p \to e^+ \pi^0 and n-nbar oscillations, or n \to e^- \pi^+ and n-nbar oscillations would establish that neutrinos are Majorana particles. We discuss this in a model-independent effective operator approach.