Formal structure of direct image of holonomic D-modules of exponential type
arXiv:math/0604134
Abstract
We compute formal invariants associated with the cohomology sheaves of the direct image of holonomic D-modules of exponential type. We also prove that every formal C[[t]]<\partial_t>-modules is isomorphic, after a ramification, to a germ of formalized direct image of analytic D-module of exponential type.
19 pages, 5 figures, supported by a fellowship of the Deutsche Forschungsgemeinschaft. Revised version