2007 Volume 61 Issue 1 Pages 21-34
Let {σt}t∈(-∞,∞) be a one-parameter family of hyperbolic Riemannian metrics on an open annulus which is continuouswith respect to the Gromov-Hausdorff topology. We consider a system Et of ordinary differential equations with singular points which depends on the Riemannian metric σt. If t ≠ 0, all of the singular points of Et are regular. If t = 0, E0 has an irregular singular point. In this paper, we investigate the behavior of the singular points of Et . We show that a regular singular point of Et , together with another regular singular point of Et , becomes the irregular singular point of E0 as t (›0) tends to zero and that the irregular singular point of E0 becomes a non-singular point of Et as t decreases from zero.