For a linear differential operator on with unramified irregular singular points, we examine a realization of as a confluence of singularities of a Fuchsian differential operator having the same index of rigidity as , which we call an unfolding of . We conjecture that this is always possible. For example, if is rigid, this is true and the unfolding helps us to study the equation .
Cite this article
Toshio Oshima, Versal Unfolding of Irregular Singularities of a Linear Differential Equation on the Riemann Sphere. Publ. Res. Inst. Math. Sci. 57 (2021), no. 3/4, pp. 893–920DOI 10.4171/PRIMS/57-3-6