On invariants of modules over the ring of differential operators (Q2082409)

Let \(K\) be a field of zero characteristic and \(R=K[[X_1,\ldots,X_n]]\) the domain of formal power series. Denote by \(D(R,K)\) the ring of differential operators over \(R\). In the paper under review, the authors investigate the weighted order filtration on \(D(R,K)\)-modules. Using the notion of holonomic \(D(R,K)\)-modules, they determine some invariants like characteristic variety, critical cone and others. Some applications are given.