CRYSTALLINE FLOW STARTING FROM A GENERAL POLYGON

This paper solves a singular initial value problem for a system of ordinary di erential equations describing a polygonal flow called a crystalline flow. Such a problem corresponds to a crystalline flow starting from a general polygon not necessarily admissible in the sense that the corresponding initial value problem is singular. To solve the problem, a self-similar expanding solution constructed by the first two authors with H. Hontani (2006) is effectively used.