LAUSR

This paper combines the graph-theoretical ideas behind Moravcsik’s theorem with a completely analytic derivation of discrete phase-ambiguities, recently published by Nakayama. The result is a new graphical procedure for the derivation of certain types of complete sets of observables for an amplitude-extraction problem with N helicity-amplitudes. The procedure is applied to pseudoscalar meson photoproduction (N = 4 amplitudes) and electroproduction (N = 6 amplitudes), yielding complete sets with minimal length of 2N observables. For the case of electroproduction, this is the first time an extensive list of minimal complete sets is published. Furthermore, the generalization of the proposed procedure to processes with a larger number of amplitudes, i.e. N > 6 amplitudes, is sketched. The generalized procedure is outlined for the next more complicated example of two-meson photoproduction (N = 8 amplitudes).