Glimpses of Algebra and Geometry (Paperback, Softcover reprint of the original 2nd ed. 2002)

viii 2. As a natural continuation of the section on the Platonic solids, a detailed and complete classi?cation of ?nite Mobius ] groupsal a Klein has been given with the necessary background material, such as Cayley s theorem and the Riemann Hurwitz relation. 3. Oneofthemostspectaculardevelopmentsinalgebraandge- etry during the late nineteenth century was Felix Klein s theory of the icosahedron and his solution of the irreducible quintic in termsofhypergeometricfunctions.Aquick, direct, andmodern approach of Klein s main result, the so-called Normalformsatz, has been given in a single large section. This treatment is in- pendent of the material in the rest of the book, and is suitable for enrichment and undergraduate/graduate research projects. All known approaches to the solution of the irreducible qu- tic are technical; I have chosen a geometric approach based on the construction of canonical quintic resolvents of the equation of the icosahedron, since it meshes well with the treatment of the Platonic solids given in the earlier part of the text. An - gebraic approach based on the reduction of the equation of the icosahedron to the Brioschi quintic by Tschirnhaus transfor- tions is well documented in other textbooks. Another section on polynomial invariants of ?nite Mobius ] groups, and two new appendices, containing preparatory material on the hyper- ometric differential equation and Galois theory, facilitate the understanding of this advanced material."