Ambiguous sets of partial-wave amplitudes cannot intersect

The correct set of partial-wave amplitudes can sometimes be distinguished from ambiguous ones because it joins continuously, as a function of energy, to a lower-energy set known unambiguously. If two sets intersect, however, this continuity criterion yields no unique answer. It is shown that such an intersection is in fact impossible in the usual experimental spin-0 spin-1/2 scattering situation. (Auth.)