Let ℳ be a coherent
𝒟-module (e.g., an overdetermined system of partial differential equations) on the
complexification of a real analytic manifold M. Assume that the characteristic
variety of ℳ is hyperbolic with respect to a submanifold N ⊂ M. Then, it is
well-known that the Cauchy problem for ℳ with data on N is well posed in the
space of hyperfunctions.
In this paper, under the additional assumption that ℳ has regular singularities
along a regular involutive submanifold of real type, we prove that the Cauchy
problem is well posed in the space of distributions.
When ℳ is induced by a single differential operator (or by a normal square
system) with characteristics of constant multiplicities, our hypotheses correspond to
Levi conditions, and we recover a classical result.
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