I'm looking for references for the various characterizations of regular holonomic D-modules, in particular proofs of their equivalence. For instance, some characterizations I've seen (in the analytic category) are:
- $\chi(M_x,\mathcal O_x) =\chi(M_x,\mathcal {\hat O}_x)$ for all $x$ source for notation (Though they give a source for this, I was unable to find it there)
- $R\operatorname{Hom}_D(M_x, \mathcal O_x) \cong R\operatorname{Hom}_D(M_x,\hat {\mathcal O}_x)$ via the natural map for all $x$
- A characterization having to do with V-filtrations near smooth points of subvarieties
- The D-module inverse image along any morphism from a smooth curve is regular in the sense of Fuchs