Recursion relations for integrals of amplitudes over the phase space, i.e.
for partial wave amplitudes, are introduced. In their simplest form these
integrals are proportional to the s-wave amplitudes and represent rigorous
lower bounds on the total cross sections. The connection with classical field
equations in D dimensions is established. Previous results on multiparticle
amplitudes are easily reproduced.Comment: 7 pages, CERN-TH.6971/93, (typing errors corrected