  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).
