The Riemann Legacy, Softcover reprint of the original 1st ed. 1997 Riemannian Ideas in Mathematics and Physics Mathematics and Its Applications Series, Vol. 417

very small domain (environment) affects through analytic continuation the whole of Riemann surface, or analytic manifold . Riemann was a master at applying this principle and also the first who noticed and emphasized that a meromorphic function is determined by its 'singularities'. Therefore he is rightly regarded as the father of the huge 'theory of singularities' which is developing so quickly and whose importance (also for physics) can hardly be overe~timated. Amazing and mysterious for our cognition is the role of Euclidean space. Even today many philosophers believe (following Kant) that 'real space' is Euclidean and other spaces being 'abstract constructs of mathematicians, should not be called spaces'. The thesis is no longer tenable - the whole of physics testifies to that. Nevertheless, there is a grain of truth in the 3 'prejudice': E (three-dimensional Euclidean space) is special in a particular way pleasantly familiar to us - in it we (also we mathematicians!) feel particularly 'confident' and move with a sense of greater 'safety' than in non-Euclidean spaces. For this reason perhaps, Riemann space M stands out among the multitude of 'interesting geometries'. For it is: 1. Locally Euclidean, i. e. , M is a differentiable manifold whose tangent spaces TxM are equipped with Euclidean metric Uxi 2. Every submanifold M of Euclidean space E is equipped with Riemann natural metric (inherited from the metric of E) and it is well known how often such submanifolds are used in mechanics (e. g. , the spherical pendulum).

I Riemannian Ideas in Mathematics and Physics.- 1 Gauss Inner Curvature of Surfaces.- 2 Sectional Curvature. Spaces of Constant Curvature. Weyl Hypothesis.- 3 Cohomology of Riemann spaces. Theorems of de Rham, Hodge, Kodaira.- 4 Chern—Gauss—Bonnet theorem.- 5 Curvature and Topology or Characteristic Forms of Chern, Pontriagin, and Euler.- 6 Kähler Spaces. Bergman Metrics. Harish-Chandra-Cartan Theorem. Siegel Space (once again!).- II General Structures of Mathematics.- 1 Differentiable Structures. Tangent Spaces. Vector Fields.- 2 Projective (Inverse) Limits of Topological Spaces.- 3 Inductive Limits. Presheaves. Covering Defined by Presheaf.- 4 Algebras. Groups, Tensors, Clifford, Grassmann, and Lie Algebras. Theorems of Bott—Milnor, Wedderburn, and Hurwitz.- 5 Fields and their Extensions.- 6 Galois Theory. Solvable Groups.- 7 Ruler and Compass Constructions. Cyclotomic Fields. Kronecker—Weber Theorem.- 8 Algebraic and Transcendental Elements.- 9 Weyl principle.- 10 Topology of Compact Lie Groups.- 11 Representations of Compact Lie Groups.- 12 Nilpotent, Semimple, and Solvable Lie Algebras.- 13 Reflections, Roots, and Weights. Coxeter and Weyl groups.- 14 Covariant Differentiation. Parallel Transport. Connections.- 15 Remarks on Rich Mathematical Structures of Simple Notions of Physics Based on Example of Analytical Mechanics.- 16 Tangent Bundle TM. Vector, Fiber, Tensor and Tensor Densities, and Associate Bundles.- 17 G-spaces. Group Representations.- 18 Principal and Associated Bundles.- 19 Induced Representations and Associated Bundles.- 20 Vector Bundles and Locally Free Sheaves.- 21 Axiom of Covering Homotopy.- 22 Serre Fibering. General Theory of Connection. Corollaries.- 23 Homology. Cohomology. de Rham Cohomology.- 24 Cohomology of Sheaves. Abstract deRham Theorem.- 25 Homotopy Group ?k(X, x0). Hopf Fibering. Serre Theorem on Exact Sequence of Homotopy Groups of a Fibering.- 26 Various Benefits of Characteristic Classes (Orientability, Spin Structures). Clifford Groups, Spin Group.- 27 Divisors and Line Bundles. Algebraic and Abelian Varieties.- 28 General Abelian Varieties and Theta Function.- 29 Theorems on Algebraic Dependence.- III The Idea of the Riemann Surface.- IV Riemann and Calculus of Variations.- 1 Introduction.- 2 The Plateau Problem.- 3 Teichmüller Theory. Riemann Moduli Problem.- 4 Riemannian Approach to Teichmiiller Theory. Harmonic Maps and Teichmüller Space.- 5 Teichmüller theory and Plateau—Douglas problem.- 6 Rescuing Riemann’s Dirichlet Principle. Potential Theory.- 7 The Royal Road to Calculus of Variations (Constantin Carathéodory).- 8 Symplectic and Contact Geometries. Conservation Laws.- 9 Direct Methods in Calculus of Variations for Manifolds with Isometries. Equivariant Sobolev Theorems. Yamabe Problem and its Relation to General Relativity.- V Riemann and Complex Geometry.- 1 Introduction.- 2 On Complex Analysis in Several Variables.- 3 Ellipticity, Runge Property, and Runge Type Theorems.- 4 Hörmander Method in Complex Analysis.- 5 Wirtinger Theorems. Metric Theory of Analytic Sets.- 6 The Problem of Poincaré and the Cousin Problems.- 7 Ringed Spaces and General Complex Spaces.- 8 Construction of Complex Spaces by Gluing and by Taking Quotient.- 9 Differential Geometry of Holomorphic Vector Bundles over Compact Riemann Surfaces and Kähler manifolds. Stable Vector Bundles, Hermite-Einstein Connections, and their Moduli Spaces.- VI Riemann and Number Theory.- 1 Introduction.- 2 The Riemann ? function.- 3 Hecke Theory.- 4 Dedekind ?K function for number field K and Selberg ?function.- Concluding Remarks.- Suggestions for Further Reading.

Nowhere can we see more concretely the enormous spiritual energy which, intially still lacking clear contours, begs to be moulded and developed by mathematicians, than in Riemann (1826-1866). He perceived mathematics and physics as one discipline and throught of himself as both mathematician and physicist. His ideas as well as their contemporary descendants are the theme of this book.