PageHeader : Funkcialaj Ekvacioj, 36 (1993) 143-185 Title : Three Applications of a Systematization of Title : Second Order Hyperbolic Equations AuthorInfo : By AuthorInfo : Fukuzo SUZUKI and Masaru TANIGUCHI AuthorInfo : (Gunma College of Technology and Waseda University, Japan) section : Introduction section : §1. Notation section : §2. The assumption and the result section : §3. Systematizations of hyperbolic equations of second order section : §4. Several properties of the dual problem section : §5. The proof of Main Theorem 1 section : §6. The proof of Main Theorem 2 section : References