Algorithmic proofs of two theorems of Stafford
  Two classical results of Stafford say that every (left) ideal of the $n$-th Weyl algebra $A_n$ can be generated by two elements, and every holonomic $A_n$-module is cyclic, i.e. generated by one element. We modify Stafford's original proofs to make the algorithmic computation of these generators possible. 
Anton Leykin