PageHeader : Funkcialaj Ekvacioj, 44 (2001) 391-440 Title : Analytical Simplification of a Nonlinear 2-System Title : with Simplified Equations Involving Infinitely Many Terms AuthorInfo : By AuthorInfo : Masahiro IWANO AuthorInfo : (Chuo University, Japan) AuthorInfo : To the memory of my brothers section : 1. Introduction section : 2. Formal transformation of the first kind section : 3. Formal transformation of the second kind section : 4. New arrangement of the formal double power series (3.10) in a single section : 5. Determinations of the coefficient functions $R_{j}(x, \zeta)$ and $S_{j}(x,z)$ section : 6. Truncated differential equations section : 7. Modified simplified equations and stable domains section : 8. Modified truncated equations and existence theorem, Part I. (Case of $\gamma\geq 0$ ) section : 9. Modified truncated equations and existence theorem, Part II. section : 10. Stable domains of the function $\eta(x)^{N}/(x\zeta(x))$ section : 11. Evaluation of the integrals of the kernel functions section : 12. Sketch of the proof of the existence theorems section : 13. Domain of holomorphy of the solution section : References