Deformations Of Surface Singularities

The present publication contains a special collection of research and review articles on deformations of surface singularities, that put together serve as an introductory survey of results and methods of the theory, as well as open problems and examples. The aim is to collect material that will help mathematicians already working or wishing to work in this area to deepen their insight and eliminate the technical barriers in this learning process. Additionally, we introduce some material which emphasizes the newly found relationship with the theory of Stein fillings and symplectic geometry. This links two main theories of mathematics: low dimensional topology and algebraic geometry.​ The theory of normal surface singularities is a distinguished part of analytic or algebraic geometry with several important results, its own technical machinery, and several open problems. Recently several connections were established with low dimensional topology, symplectic geometry and theory of Stein fillings. This created an intense mathematical activity with spectacular bridges between the two areas. The theory of deformation of singularities is the key object in these connections.

Singularity theory is a young, rapidly-growing topic with connections to algebraic geometry, complex analysis, commutative algebra, representations theory, Lie groups theory and topology, and many applications in the natural and technical sciences. This book presents the basic singularity theory of analytic spaces, including local deformation theory and the theory of plane curve singularities. It includes complete proofs.

This monograph provides a comprehensive introduction to the theory of complex normal surface singularities, with a special emphasis on connections to low-dimensional topology. In this way, it unites the analytic approach with the more recent topological one, combining their tools and methods. In the first chapters, the book sets out the foundations of the theory of normal surface singularities. This includes a comprehensive presentation of the properties of the link (as an oriented 3-manifold) and of the invariants associated with a resolution, combined with the structure and special properties of the line bundles defined on a resolution. A recurring theme is the comparison of analytic and topological invariants. For example, the Poincaré series of the divisorial filtration is compared to a topological zeta function associated with the resolution graph, and the sheaf cohomologies of the line bundles are compared to the Seiberg–Witten invariants of the link. Equivariant Ehrhart theory is introduced to establish surgery-additivity formulae of these invariants, as well as for the regularization procedures of multivariable series. In addition to recent research, the book also provides expositions of more classical subjects such as the classification of plane and cuspidal curves, Milnor fibrations and smoothing invariants, the local divisor class group, and the Hilbert–Samuel function. It contains a large number of examples of key families of germs: rational, elliptic, weighted homogeneous, superisolated and splice-quotient. It provides concrete computations of the topological invariants of their links (Casson(–Walker) and Seiberg–Witten invariants, Turaev torsion) and of the analytic invariants (geometric genus, Hilbert function of the divisorial filtration, and the analytic semigroup associated with the resolution). The book culminates in a discussion of the topological and analytic lattice cohomologies (as categorifications of the Seiberg–Witten invariant and of the geometric genus respectively) and of the graded roots. Several open problems and conjectures are also formulated. Normal Surface Singularities provides researchers in algebraic and differential geometry, singularity theory, complex analysis, and low-dimensional topology with an invaluable reference on this rich topic, offering a unified presentation of the major results and approaches.

Here is a deformation theory for degenerations of complex curves; specifically, discussing deformations which induce splitting of the singular fiber of a degeneration. The author constructs a deformation of the degeneration in such a way that a subdivisor is "barked," or peeled off from the singular fiber. "Barking deformations" are related to deformations of surface singularities, in particular, cyclic quotient singularities, as well as the mapping class groups of Riemann surfaces via monodromies.

A phenomenon which appears in nature, or human behavior, can sometimes be explained by saying that a certain potential function is maximized, or minimized. For example, the Hamiltonian mechanics, soapy films, size of an atom, business management, etc. In mathematics, a point where a given function attains an extreme value is called a critical point, or a singular point. The purpose of singularity theory is to explore the properties of singular points of functions and mappings. This is a volume on the proceedings of the fourth Japanese–Australian Workshop on Real and Complex Singularities held in Kobe, Japan. It consists of 11 original articles on singularities. Readers will be introduced to some important new notions for characterizations of singularities and several interesting results are delivered. In addition, current approaches to classical topics and state-of-the-art effective computational methods of invariants of singularities are also presented. This volume will be useful not only to the singularity theory specialists but also to general mathematicians. Contents:On the CR Hamiltonian Flows and CR Yamabe Problem (T Akahori)An Example of the Reduction of a Single Ordinary Differential Equation to a System, and the Restricted Fuchsian Relation (K Ando)Fronts of Weighted Cones (T Fukui and M Hasegawa)Involutive Deformations of the Regular Part of a Normal Surface (A Harris and K Miyajima)Connected Components of Regular Fibers of Differentiable Maps (J T Hiratuka and O Saeki)The Reconstruction and Recognition Problems for Homogeneous Hypersurface Singularities (A V Isaev)Openings of Differentiable Map-Germs and Unfoldings (G Ishikawa)Non Concentration of Curvature near Singular Points of Two Variable Analytic Functions (S Koike, T-C Kuo and L Paunescu)Saito Free Divisors in Four Dimensional Affine Space and Reflection Groups of Rank Four (J Sekiguchi)Holonomic Systems of Differential Equations of Rank Two with Singularities along Saito Free Divisors of Simple Type (J Sekiguchi)Parametric Local Cohomology Classes and Tjurina Stratifications for μ-Constant Deformations of Quasi-Homogeneous Singularities (S Tajima) Readership: Mathematicians in singularity theory or in adjacent areas; advanced undergraduates and graduate students in mathematics; non-experts interested in singularity theory and its applications. Key Features:Contains applications of the singularity theory to other mathematical fieldsNew topics in singularity theory, e.g. the relationship between free divisors and holonomic systems, openings of differentiable map-germs, non-concentration of curvatureIncludes articles by prize-winning researchers like Kimio Miyajima and Osamu SaekiKeywords:Singularities;CR Structure;Deformation Theory;Free Divisor;Concentration of Curvature;Holonomic System;Front;Opening