# Contents

## Idea

(Solutions of) holonomic systems of differential equations are formalized in the notion of a holonomic D-module. A D-module $M$ on a smooth complex analytic variety $X$ of dimension $n$ is holonomic if its characteristic variety is of dimension $n$. It follows that the characteristic variety of a holonomic D-module is conic and lagrangian.

Holonomicity of D-modules is important also in geometric representation theory.

## References

Lecture notes include