NONEXISTENCE OF TRAVELING-WAVE SOLUTIONS TO NONELLIPTIC NONLINEAR SCHRODINGER-EQUATIONS

By deriving Pohojaev-type identities we prove that nonelliptic nonline ar Schrodinger equations do not admit localized travelling wave soluti ons. Similarly, we prove that the Davey-Stewartson hyperbolic-elliptic systems do not support travelling wave solutions except for a specifi c range of the parameters that comprises the DS II focusing case (wher e the existence of lumps is well known).