Lev Kapitanski and Yuri Safarov
Dispersive smoothing for Schr\"odinger equations
(39K, AMSTeX)

ABSTRACT.  We study the regularity of the fundamental solution 
(Green's function, propagator) for the initial or 
initial boundary value problem for the Schr\"odinger 
equation (or system) with variable coefficients. 
Under certain assumptions, the most essential of
which is the appropriate non-trapping condition, 
we prove that the only singularity of the fundamental 
solution is at $t=0$.