PageHeader : Funkcialaj Ekvacioj, 30 (1987) 399-416 Title : On Sufficient Conditions for Convergence Title : of Formal Solutions AuthorInfo : By AuthorInfo : Masafumi YOSHINO AuthorInfo : (Tokyo Metropolitan University, Japan) section : 1. Introduction section : 2. Statement of main theorem section : 3. Proof of Theorem 2.1 section : 4. Fundamental properties of $F_{\sigma}(t)$ . section : 5. A Diophantine type necessary and sufficient condition section : References