Normal Forms and Stability of Hamiltonian Systems

Since the beginning, the Hyperstructure Theory and particu- larly the Hypergroup Theory, had applications to several domains. Marty, who introduced hypergroups in 1934, applied them to groups, algebraic functions and rational fractions. New applications to groups were also found among others by Eaton, Ore, Krasner, Utumi, Drbohlav, Harrison, Roth, Mockor, Sureau and Haddad. Connections with other subjects of classical pure Mathematics have been determined and studied: * Fields by Krasner, Stratigopoulos and Massouros Ch. * Lattices by Mittas, Comer, Konstantinidou, Serafimidis, Leoreanu and Calugareanu * Rings by Nakano, Kemprasit, Yuwaree * Quasigroups and Groupoids by Koskas, Corsini, Kepka, Drbohlav, Nemec * Semigroups by Kepka, Drbohlav, Nemec, Yuwaree, Kempra- sit, Punkla, Leoreanu * Ordered Structures by Prenowitz, Corsini, Chvalina IX x * Combinatorics by Comer, Tallini, Migliorato, De Salvo, Scafati, Gionfriddo, Scorzoni * Vector Spaces by Mittas * Topology by Mittas , Konstantinidou * Ternary Algebras by Bandelt and Hedlikova.

The topics here include convex polyhedrons and closed surfaces, an elementary proof and extension of Minkowski’s theorem, Riemannian geometry and a method for Dirichlet problems. This monograph, published in English for the first time, gives unparalleled access to a brilliant mind, and advanced students and researchers in applied mathematics and geometry will find it indispensable.

The timeliness of a manuscript is more than its form, which may be unfinished or tentative. Thus, in some instances, proofs may be merely outlined and results presented which have been or will later be published elsewhere. If possible, a subject index should be included. Publication of Lecture Notes is intended as a service to the international mathematical community, in that a commercial publisher, Springer-Verlag, can offer a wide distribution of documents which would otherwise have a restricted readership. Once published and copyrighted, they can be documented in the scientific literature.